2001-02 Annual Water Quality Monitoring Report

Transcription

Sydney Catchment Authority
Water Quality Monitoring Report 2001–2002
Part 1: Summary
Water Quality Monitoring Report 2001–2002 – Part 1
Acknowledgements:
Data Analysis: Douglas Partners Pty Ltd
Editorial: Brendan Atkins, Big Box Publishing Pty Ltd
Report Project Team: SCA Bulk Water – Hydrology team, SCA Communications team
Design: Advertising Designers’ Group
Print: Eco Design – Eco Print
page 2
Contents
Foreword
4
1.
About the Sydney Catchment Authority
5
2.
Why water quality is monitored
6
3.
About this report
7
4.
Sydney’s water catchments and supply network
12
5.
Where water quality is monitored
18
6.
Water quality standards
22
7.
Key findings
24
8.
Summary of results by system
26
9.
Trends in water quality
32
10. Where to go for more information
33
11. References
33
12. Glossary of terms
34
13. Contacting the Sydney Catchment Authority
37
page 3
Foreword
Each year the Sydney Catchment Authority (SCA) undertakes a comprehensive water quality
monitoring program for the rivers and reservoirs that supply water to Sydney, the Blue Mountains
and Illawarra.
Water quality during 2001-2002 was generally good. Despite the wide extent of the Christmas
2001 fires in the Special Areas surrounding the SCA’s water storages, there were no immediate
adverse impacts on quality of water supplied by the SCA. Monitoring for medium-term impacts of
the fires is continuing.
A summary of the results of the water quality monitoring program for 2001-2002 is contained in
Part 1 of this report. Parts 2, 3 and 4 provide more detailed analyses on: performance of the water
delivery system in relation to the SCA’s Operating Licence and Bulk Water Supply Agreement;
results of river temperature monitoring below major reservoirs; and monitoring for SCA
operational and planning purposes.
Over the next five years, the SCA aims to identify and mitigate those activities that may adversely
impact on water quality. Priority measures include: reducing sewage discharges and sediment
load, improving the quality of stormwater and other urban run-off, and endorsing sustainable land
use and vegetation management. The SCA has also adopted a proactive strategy to reduce the
incidence and severity of cyanobacteria (blue-green algae) outbreaks by identifying and mitigating
activities within the catchment that contribute to cyanobacteria in our waterways and storages.
The SCA’s water quality monitoring program continues to inform the development and delivery of
our projects that ensure the bulk raw water delivered by the SCA continues to be of the highest
quality.
Graeme Head
Chief Executive
page 4
1 About the Sydney Catchment Authority
1.1 What the Sydney Catchment Authority does
The Sydney Catchment Authority (SCA) is a NSW state government agency responsible for
managing the catchments, dams and infrastructure that provide Sydney’s bulk water supply. It was
established in 1999 following an independent NSW government inquiry into Sydney’s water
supply.
Drinking water for Sydney and surrounding areas is collected from five primary catchments,
occupying 16 000 square kilometres. It is stored in a total of 21 dams, holding over 2.5 million
megalitres of water.
One of the SCA’s main tasks is to supply quality bulk raw water to its customers, which include
Sydney Water, local councils in the Southern Highlands and the Shoalhaven and a number of
direct users. Sydney Water and the Councils then treat and distribute the water to nearly four
million people - about 60 per cent of NSW's population.
1.2 The SCA’s responsibilities
The SCA aims to ensure that its catchments and the supply infrastructure are managed and
protected to:
promote water quality
minimise risks to human health, and
prevent degradation of the environment.
The SCA takes a lead role in managing its catchment areas by:
monitoring water quality across the catchment.
establishing partnerships with stakeholders such as councils, government agencies,
community groups, customers and landholders
having a formal role in planning and development in the catchments
page 5
offering grants and funding opportunities such as the Healthy Catchments Program,
sponsorship opportunities and collaborative research, and
monitoring water quality across the catchments.
Through these activities, the SCA fosters teamwork within the SCA, across government and with
the community to help protect and clean up the catchments. Its charter gives the SCA a regulatory
role in the way catchments are managed. This helps to reduce the risk of contamination arising
from inappropriate land uses.
2 Why water quality is monitored
The SCA’s water quality monitoring program is a key tool for managing the catchments
effectively and providing quality water to its customers. The monitoring program assists in
understanding the threats to water quality throughout the delivery system – from streams to
storages – while indicating when water in the catchments and that delivered to customers, meets
agreed national standards for water quality.
There are many risks that could lead to the contamination of Sydney’s water supply. These
include:
disease causing organisms (pathogens)
sediment, which affects turbidity
metals, which affect the taste of water
nutrients, which can cause algal blooms
algae, which cause odour problems, increase treatment time and cost, and may impact health,
and
contaminants, such as pesticides.
The SCA uses the data collected from its water quality monitoring program to:
provide early detection of possible contaminants in the water to help protect the health of
approximately four million consumers
page 6
ensure that the untreated water that it delivers to customers such as Sydney Water is of an
appropriate quality. This is turn enables these organisations to give greater assurance to their
customers that their drinking water meets Australian Drinking Water Guidelines
assist it to identify and target possible sources of contamination in the catchments and
storages, and
help it identify emerging water quality issues so that it can address them in its forward
planning.
The SCA also has a number of statutory obligations that guide the content of its water quality
monitoring program.
2.1 Statutory responsibilities
When it was formed in 1999, the SCA’s charter set out its statutory responsibilities in order to
maintain its licence to supply water. Several Acts of Parliament define the scope and mode of SCA
operations, primarily the Sydney Water Catchment Management Act 1998.
The SCA’s day-to-day activities are governed by three key documents:
Operating Licence (granted by the Governor of NSW)
Water Management Licence granted by The Water Administration Ministerial Corporation
and administered by the Department of Land and Water Conservation (DLWC), and
Bulk Water Supply Agreement (BWSA) between the SCA and Sydney Water Corporation.
Operating Licence
The SCA’s Operating Licence enables the SCA to:
manage and protect the catchment area and infrastructure,
supply bulk water, and
regulate activities within the catchment area.
The Operating Licence conditions require the SCA to meet its objectives and comply with water
quality and performance standards. The SCA is audited on its performance each year and the
Operating Licence must be renewed every five years.
page 7
Under the terms of its Operating Licence, the SCA monitors water delivered to its customers for
the characteristics specified in the BWSA (Table 1) as well as for the characteristics listed in Table
2 of this report. This list from Schedule 4 of the Operating Licence includes substances not
substantially removed or reduced by water treatment processes.
Water Management Licence
Under the Water Act 1912, a licence is needed before water can be extracted from rivers or dams.
The Water Administration Ministerial Corporation (WAMC) is the licensing authority for this Act.
The WAMC granted a Water Management Licence to the SCA in April 2001. The licence,
administered by the Department of Land and Water Conservation (DLWC), sets out specifications
for water transfers and releases, including environmental flows, and specifies monitoring and
reporting needs.
The SCA releases environmental flows from reservoirs to maintain the ecological health of
downstream rivers. The SCA also monitors the effect of these releases on downstream river
temperatures as required.
Bulk Water Supply Agreement
The SCA has developed a BWSA with its major customer, Sydney Water, which addresses both
the quality and quantity of bulk water supply. In the BWSA, the SCA agrees to provide bulk raw
water to Sydney Water’s nine water filtration plants (WFPs), and meet national water quality
standards set by the Australian and New Zealand Environment and Conservation Council
(ANZECC) and the National Health & Medical Research Council (NHMRC).
The SCA also supplies raw water to WFPs owned by Shoalhaven City Council and Wingecarribee
Shire Council. BWSAs are being finalised with these customers.
The BWSA with Sydney Water sets site-specific standards at each WFP for characteristics such as
turbidity, alkalinity and colour, all of which determine the treatability of the water. The standards
vary between WFPs because of:
differences in the design of the WFPs, and
differences in the water chemistry between source catchments.
The guidelines applying at each WFP are shown in Table 1.
page 8
2001–2002
Healthy Catchments, Quality Water
3 About this report
Each year, the SCA reports the results of its extensive water quality monitoring program. As well
as meeting the SCA's statutory obligations, the report aims to provide stakeholders, students,
researchers and other members of the community with detailed information on the quality of water
for which the SCA is responsible. More specifically, this report aims to:
detail how the system has performed relative to water quality criteria at each location
map the water quality in catchments, reservoirs and delivery systems
interpret the results of the collected water quality data
summarise and explain the findings in plain English wherever possible
describe water quality trends and problems identified by the monitoring program
report on targeted studies, and
report on measures planned or taken to eliminate unacceptable water quality.
The 2001-2002 report is presented in four parts:
Part 1: Introduces the SCA and its activities, provides an overview of how the SCA collects,
stores and distributes water, and explains why the SCA needs to monitor water quality. This part
then broadly sums up all of the SCA’s water quality monitoring activities and results from July
2001 to June 2002.
Part 2: Details how the delivery system has performed in relation to the SCA Operating Licence
and Bulk Water Supply Agreement between SCA and Sydney Water.
Part 3: Details the results of river temperature monitoring below major reservoirs, undertaken to
fulfil the needs of the Water Management Licence.
Part 4: Summarises the results of monitoring carried out by the SCA for operational and planning
purposes.
The full report can be viewed on the SCA’s website (www.sca.nsw.gov.au).
page 9
Analytes (Unit)
Catchment
o
Temperature ( C)
na
Storage
Reservoirs
(Lake)
na
Delivery System (site-specific guidelines)
Prospect
Warragamba
Orchard Hills
Macarthur
Nepean
Illawarra
Woronora
Cascade
Greaves Ck
10.0–23.6
8.8–24.1
8.0–25.0
10.0–25.0
10.0–26.6
5.0–24.0
5.0–25.0
Dissolved Oxygen (% saturation)
90–110
90–110
na
na
na
na
na
na
na
pH (pH unit)
6.5-8.0
6.9-8.1* (LB)
6.0-7.2** (O)
6.27–7.87
5.72–7.65
4.80-7.65
6.15–7.20
5.06–7.54
6.00-7.40
4.40-9.20
Alkalinity (mg CaCO3/L)
na
na
21–45
0.8–14
0.5–45
0.6–7.6
0.5–12.5
0.5–31
0.5–10
Hardness (mg CaCO3/L)
na
na
28.5–53.5
6.4–32.2
2.1–30
5.2–23
2.6–22.8
40
1.5–6.6
Turbidity (NTU)
25
20
40
60
183
10
11
15
40
True Colour (CU)
na
na
60
40
60
48
70
60
60
Total Iron (mg/L)
na
0.3
3.5
1.3
5
1.12
1.0
3.0
2.8
Total Manganese (mg/L)
na
0.1
1.40
0.35
1.45
0.37
0.07
0.25
1.00
Total Aluminium (mg/L)
na
0.2
2.58
0.95
1.00
1.401
0.4
0.18
1.00
Total Phosphorus (mg/L)
0.050
0.010
na
na
na
na
na
na
na
Total Nitrogen (mg/L)
0.50
0.35
na
na
na
na
na
na
na
Thermotolerant Coliforms (CFU/100 mL)
150
100
na
na
na
na
na
na
na
Enterococci (CFU/100 mL)
na
na
na
na
na
na
na
na
na
Chlorophyll-a (µg/L)
7
5
na
na
na
na
na
na
na
Algal ASU (per mL)
na
na
1000
500
1000
5000
5000
1000
1000
Cyanobacteria Abundance (cells/mL)
na
15000
na
na
na
na
na
na
na
Toxigenic Cyanobacteria (cells/mL)
na
2000
na
na
na
na
na
na
na
(mm2/L)
na
2
na
na
na
na
na
na
na
Cyanobacterial Biovolume
Part 1 - Table 1: Water Quality Guidelines
References: SCA (1999); ANZECC (2000); HRC (1998); NHMRC (1996); SACC (2001); SCA (2000); SWC (1999)
Notes: * LB = Lake Burragorang and Prospect Reservoir; ** O = other lakes. na = not applicable.
page 10
Part 1 -Table 2: Guidelines for trace elements and contaminants (for Sydney Water WFPs only)
Analyte
Guideline
Unit
Total Arsenic
0.007
mg/L
Total Barium
0.7
mg/L
Total Boron
0.3
mg/L
Total Mercury
0.001
mg/L
Total Molybdenum
0.05
mg/L
Total Selenium
0.01
mg/L
Total Silver
0.1
mg/L
Iodide
0.1
mg/L
Aldrin
3.0
µg/L
Amitrole
1.0
µg/L
Atrazine
20.0
µg/L
Chlordane
1.0
µg/L
Chlorpyrifos
2.0
µg/L
1000.0
µg/L
2 4-Dichloro-phenoxy-acetic acid
30.0
µg/L
DDT
20.0
µg/L
0.3
µg/L
Diquat
5.0
µg/L
Diuron
30.0
µg/L
Total Endosulfan
30.0
µg/L
0.3
µg/L
300.0
µg/L
20.0
µg/L
Molinate
5.0
µg/L
Paraquat
30.0
µg/L
Picloram
300.0
µg/L
Propiconazole
100.0
µg/L
Temephos
300.0
µg/L
10.0
µg/L
Clopyralid
Dieldrin
Heptachlor
Hexazinone
Lindane
Triclopyr
Gross Alpha emitters
0.1
Bq/L
Gross Beta emitters
0.5
Bq/L
Source: National Health and Medical Research Council (NHMRC) (1996);
Schedule 4 of the SCA Operating Licence
page 11
4 Sydney’s water catchments and supply network
Drinking water for almost four million people in the Sydney region is collected from river
catchments to the south and west of Sydney and stored in a number of lakes and reservoirs. The
water is subsequently released into a network of rivers, pipes and canals that transport it to water
filtration plants (WFPs), which treat water supplies for consumers in Sydney, Illawarra, the Blue
Mountains and the Southern Highlands. Water is also released from reservoirs to maintain the
ecological health of the downstream river systems.
Part 1 - Figure 1 presents a diagram of the SCA’s water supply network.
The SCA’s bulk water supply is collected from the river systems of five major catchments:
Warragamba
Upper Nepean
Woronora
Shoalhaven, and
the Blue Mountains.
These catchments span 18 local government areas covering an area of almost 16 000 square
kilometres. They extend from the headwaters of the Coxs River north of Lithgow, south to the
source of the Shoalhaven River near Cooma, and from Woronora in the east to the source of the
Wollondilly River near Crookwell in the west. Table 3 summarises the characteristics of each
system.
page 12
Part 1 - Figure 1: The SCA’s water supply network with links to SWC’s WFP’s and delivery network
page 13
Part 1 - Table 3 Specifications of major delivery systems in the water supply network
delivery system
major storages
total capacity
(ML)
catchment area
(square kilometres)
Warragamba
Lake Burragorang
2 057 000
9050
Upper Nepean
Cataract
94 300
130
Cordeaux
93 600
91
Upper Cordeaux 1
775
Included in above
Upper Cordeaux 2
1180
Included in above
Avon
214 360
142
Nepean
70 170
320
Woronora
Woronora
71 800
75
Shoalhaven
Lake Yarrunga
85 500
5586
1200
Included in above
Fitzroy Falls
23 500
Included in above
Wingecarribee
34 500
Included in above
Lower Cascade
319
20
Middle Cascade
159
Included in above
Upper Cascade
1700
Included in above
Lake Medlow
297
5
Greaves Creek
311
7
Woodford
850
9
Bendeela
Blue Mountains
Note The total capacity of a reservoir is the amount of water it can hold when full. Operational restrictions
reduce the amount of useable water that the SCA can supply to its customers.
page 14
4.1 Warragamba System
The Warragamba catchment is about 9050 square kilometres, with the lake itself covering 75
square kilometres. Land within the catchment is predominantly natural bushland and unfertilised
grazing land. Twenty-five per cent of the Warragamba catchment is a declared Special Area,
comprising mainly unspoilt bushland in which public access is restricted to protect water quality.
Lake Burragorang, formed behind Warragamba Dam, is the largest reservoir that the SCA
manages. With a total capacity of more than two million megalitres (ML) - four times the volume
of Sydney Harbour - Lake Burragorang supplies up to 80 per cent of all Sydney’s water.
The Warragamba delivery system consists of large-diameter pipes, which transport water by
gravity from Lake Burragorang to WFPs at Warragamba, Orchard Hills and Prospect. The water is
monitored at numerous points in the lake, in the pipeline and at the inlets to the treatment plants.
4.2 Upper Nepean System
Four dams on the Illawarra Plateau collect water from the Nepean, Avon, Cordeaux and Cataract
rivers. Together they provide an additional supply of water for Sydney, via Broughtons Pass Weir
and the Upper Canal. The main purpose of Avon Reservoir however is to serve the Illawarra
region.
The Nepean Reservoir has the largest catchment (320 square kilometres) of the four reservoirs.
Land within the Nepean catchment is predominantly either natural bushland or land used for
grazing and cropping. Forestry, intensive agriculture and mining are also found there.
Nepean Reservoir supplies water to Nepean Water Filtration Plant (WFP) as well as to Macarthur
and Prospect WFPs. The Nepean WFP supplies drinking water to the surrounding rural area and
the local townships of Bargo, Thirlmere, Picton and The Oaks.
Cordeaux and Cataract reservoirs have catchments of 91 and 130 square kilometres respectively.
Much of these catchments are Special Areas, containing largely unspoilt bushland. Cataract and
Cordeaux reservoirs feed the Macarthur and Prospect WFPs.
The Macarthur WFP, operated under contract to Sydney Water, supplies drinking water sourced
from the Upper Canal Delivery System at Broughtons Pass Weir to the Camden, Campbelltown
and Wollondilly local government areas. The Prospect WFP is also partially supplied from the
Upper Canal.
The Avon Reservoir has a catchment area of 142 square kilometres and is mainly highly protected
bushland. Water is transported from the upper reaches of Avon Reservoir by gravity and, in
drought times, by pumping, to the Illawarra WFP.
page 15
4.3 Woronora System
The Woronora catchment is predominantly bushland and covers 77 square kilometres. Woronora
Reservoir, located on the southern outskirts of Sydney, delivers water via a pipe system to
Woronora WFP, which supplies approximately 100 000 residents of Helensburgh and Engadine.
4.4 Blue Mountains System
The Blue Mountains catchments are predominantly bushland covering more than 20 square
kilometres. The three Cascade reservoirs at Katoomba, and lakes Greaves and Medlow near
Medlow Bath, are the five of the smallest reservoirs managed by the SCA. The system provides
water to residents of the mid and upper Blue Mountains.
The Blue Mountains Delivery System is a complex network of pipes that can deliver water from
both within and outside the Blue Mountains catchments. Greaves Creek Reservoir typically
supplies the Greaves Creek WFP, with Lake Medlow as a supplementary source. The Cascade
reservoirs supply the Cascade WFP, which can be supplemented with water transferred from Lake
Oberon on the Fish River, west of the Great Dividing Range.
4.5 Shoalhaven System
The Shoalhaven System includes the Shoalhaven Scheme, an engineered network of dams, canals
and pipelines, built to transfer water from the catchments of the Shoalhaven River to Sydney
during times of drought. It is also used by Eraring Energy to generate electricity.
Its major storage is Lake Yarrunga, at the junction of the Kangaroo and Shoalhaven rivers, which
covers an area of 8.3 square kilometres. The Shoalhaven catchment covers an area of 5586 square
kilometres having a mix of land uses, including bushland, dairy farming, beef and sheep
production, and rural residential.
When required, water is transferred via pumps, pipeline, channel and river from the Shoalhaven
system to either the Warragamba or the Nepean systems. The SCA releases water downstream into
the Shoalhaven River for the Shoalhaven City Council to distribute to its customers and to help
with the health of the river.
The Bendeela Pondage is a very small impoundment in the delivery system connecting Lake
Yarrunga with Fitzroy Falls Reservoir. The water supply for the residents of Kangaroo Valley is
drawn from here. Raw water is treated at a WFP operated by Shoalhaven Shire Council.
Wingecarribee Reservoir supplies water to Wingecarribee WFP which supplies many residents of
the Southern Highlands with drinking water.
page 16
4.6 Hawkesbury-Nepean River
Below the major storage reservoirs in the Warragamba and Nepean catchments, the HawkesburyNepean River is sustained by:
flows from local catchments
flows of treated effluent from Sydney Water’s Sewage Treatment Plants (STPs), and
environmental releases from SCA storages which help maintain and improve the ecological
health of the river.
The Department of Land & Water Conservation licences various water extractions along the length
of the Hawkesbury-Nepean River for agricultural and some industrial use. Sydney Water also
draws water from the river at North Richmond to supply consumers in that area.
page 17
5 Where water quality is monitored
In 2001–2002, the SCA undertook extensive water quality monitoring throughout its entire water
supply network, covering:
the catchment waterways
the reservoirs
the delivery systems that supply water to filtration plants (WFPs), and
the rivers downstream of the reservoirs.
The SCA works with catchment communities to monitor water quality in local streams as part of
its Streamwatch program. The focus of this program is on tackling pollution sources by working
in partnership with the community. The results of Streamwatch testing can be viewed at
www.streamwatch.org.au .
5.1 Water quality in catchments
Natural catchments
Natural bushland yields relatively clean water that has few of the nutrients that can cause problems
in reservoirs. However, heavy rainfall after a prolonged dry spell can bring high sediment loads,
leaves, branches and native animal droppings to the rivers and lakes. Generally, the SCA does not
monitor the quality of water coming from natural catchments, although it monitors wet-weather
water quality and has also assessed the water quality impacts of extensive bushfires in 2001–2002.
Around 25 per cent of the water supply catchments are designated Special Areas. These areas of
unspoilt bushland close to reservoirs act as a buffer zone and help to stop pollutants from entering
the reservoirs. They are managed jointly with the NSW National Parks & Wildlife Service
(NPWS), in accordance with the Special Areas Strategic Plan of Management, which can be
viewed at www.sca.nsw.gov.au/publications . Public access to Special Areas is restricted to help
protect water quality.
Agricultural catchments
Runoff from farmland can bring soil, animal droppings and traces of agricultural chemicals, such
as fertilisers, pesticides or herbicides. The SCA works in partnership with farmers throughout the
page 18
catchments to try and minimise the amounts of these materials that find their way into streams and
rivers.
Urban catchments
Urban areas contribute many undesirable impurities to water, from oil and grease washed off
roads, to household and garden chemicals, rubbish and animal droppings. The SCA is supporting
the Environment Protection Authority (EPA) and local councils in raising public awareness about
the need to improve stormwater quality. The SCA is also funding infrastructure works such as
gross pollutant traps.
A note about wetlands
Some hollows, depressions and other poorly drained areas called wetlands hold water for some
time, allowing specialised vegetation to develop and grow and forming habitats for a diversity of
aquatic or semiaquatic animals – invertebrates, fish, frogs, waterbirds and mammals. Wetlands can
affect water quality by filtering sediment and transforming nutrients as the water passes through.
Wingecarribee Swamp upstream of Wingecarribee Reservoir is a significant peat swamp, and
several other types of wetlands can be found in SCA catchments.
5.2 Water quality in streams and rivers
Once the rainfall has made its way into streams and rivers, instream processes begin to affect water
quality. Examples of instream processes include:
nutrient assimilation by algae, sediments and biochemical transformations
oxygenation by flowing water, algae and streamside vegetation
disinfection by ultraviolet rays in natural sunlight, and
riverbank erosion and streambed scouring which contribute sediment to the water column
during periods of high flow.
Some of these features of streams are useful where treated effluent from sewage treatment plants is
released to rivers. The effluent must meet strict quality standards set by the EPA and Department
of Health before being discharged. The long distances between the discharge point and the dam
wall ensures that instream processes protect the health of supplies. Additionally, the SCA
monitoring program helps to protect human health.
page 19
5.3 Water quality in reservoirs
The quality of water stored in reservoirs is determined both by the quality of the inflows and by inlake processes. Inflowing rivers transport materials such as nutrients, sediments and other
contaminants which may then be transformed as a result of:
settling
biochemical action, and
thermal stratification.
Thermal stratification in particular plays a large part in determining the quality of water in
reservoirs and lakes.
Thermal stratification
Surface warming from the sun, or inflows of cool river water, help the water in the deeper
reservoirs to form separate layers, especially over the summer months. The upper layer (surface
layer) is warmer and less dense than the cooler bottom water, leading to a water density gradient
and eventually to two layers separated by a sharp temperature difference (called a thermocline).
These two water masses can have distinct characteristics (apart from temperature and density)
which together affect water quality and living things (especially algae).
Stratified reservoirs can increase the concentrations of several undesirable water quality
characteristics, such as:
metals such as iron and manganese (Fe and Mn)
nutrients such as phosphorus and nitrogen (P and N)
algae and cyanobacteria (blue-green algae), and
turbidity and pathogens during wet weather.
The SCA artificially mixes a number of its reservoirs to prevent the water quality problems caused
by stratification. For example in Woronora Reservoir air compressors bubble air into the bottom
layer of water. The bubbles mix the layers as they float to the surface. In other storages, floating
fans drive the surface water downwards to break up the thermocline.
This artificial mixing circulates oxygenated water from the upper layer throughout the reservoir,
replenishing oxygen lost from the bottom layer, and preventing metals entering the water from the
sediments.
page 20
5.4 Delivery systems
The SCA monitors water quality in the pipelines, Upper Canal and at the inflow points to the water
filtration plants. This monitoring program helps the SCA to ensure the quality of water supplied
to the water filtration plants via the delivery systems meets agreed standards.
The SCA also provides drinking water to picnic areas at Avon, Cataract, Cordeaux and Tallowa
Dams and Fitzroy Falls reservoir. Each week, the SCA monitors the quality of these water supplies
and assesses the results against NHMRC (1996) guidelines for public health and aesthetics.
5.5 Rivers downstream of reservoirs
The SCA releases water from reservoirs to maintain the ecological health of downstream rivers.
The discharged reservoir water can be colder than the receiving river water. Although the
ecological effects of decreases in water temperature are not fully understood, the SCA monitors
this potential environmental impact as part of its commitment to the environment. A total of 12
sites, either immediately downstream of the discharge point (discharge sites) or many kilometres
away (reference or control sites), are monitored each day on the Hawkesbury-Nepean, Woronora
and Shoalhaven rivers. The water temperature at discharge sites is compared with controls to
assess the impact of the releases.
page 21
6 Water quality standards
The SCA has adopted nationally recognised standards and guidelines for a range of water quality
variables within each part of the water supply network. Different guidelines and standards apply to
each part of the supply cycle as water passes from catchment waterways into storage reservoirs
and then into the distribution system or downstream rivers. The source of each guideline and the
component of the water supply system to which it applies are listed in Table 1.
Catchment water quality is measured against ANZECC water quality guidelines (2000) and the
Healthy Rivers Commission (1998) guidelines for river water quality. Standards for water supplied
to WFPs from reservoirs are detailed in the NHMRC Australian Drinking Water Guidelines (1996)
and are also listed in Schedule 4 of the Operating Licence. The BWSA specifies site-specific
standards for the quality of water supplied to each WFP.
The results in parts two to four of this report identify where guideline levels were not met.
6.1 Guidelines for catchments and reservoirs
The trophic (algal growth) status of catchment waterways is usually assessed against ANZECC
Guidelines for Protection of Aquatic Ecosystems.
In some cases the SCA has adopted more stringent guidelines than ANZECC, such as the Healthy
Rivers Commission (HRC 1998) guidelines for algal nutrients and chlorophyll in the HawkesburyNepean River and catchment, and the Sydney Water (SWC 1999) guideline for pH in storage
reservoirs.
Guidelines for cyanobacteria
Cyanobacteria are microscopic single-celled organisms sometimes known as blue-green algae.
Like all algae they become a problem when they occur in high densities (‘blooms’), usually
because of warm weather, high nutrient concentrations or both. Apart from clogging filtration
equipment and imparting tastes and odours to the water, some species exude toxic compounds that
can cause illness and even death in stock and humans.
The guidelines for cyanobacteria are recommended by NSW State Algal Coordinating Committee
(SACC 2001) and NHMRC (2001). Based on these, the SCA identifies any instance when the total
number of cyanobacteria exceeds 15 000 cells per millilitre (cells/mL) or toxigenic cyanobacteria
of more than 2000 cell/mL. Such events trigger additional monitoring which includes analysing for
the presence of algal toxins.
However, different species of cyanobacteria and algae vary greatly in size and shape, which can
reduce the effectiveness of guidelines based on cell number alone. For example, a low cell count
of a large-celled species may indicate just as much of a problem as a high count of a small-celled
species, yet may be within the guidelines. Also, some cyanobacteria have extremely small cells
that occur in large masses, making counting inaccurate.
page 22
Recognising these differences, the SACC issued a guideline in February 2001 based on cell
volume for non-toxic cyanobacteria in recreational waters. The SCA has adopted this guideline
which recommends a maximum biovolume of two cubic millimetres per litre (mm3/L). The
biovolume guideline was applied to samples from reservoirs used for recreation, namely Lake
Yarrunga and Fitzroy Falls Reservoir.
Where toxigenic species are detected above guideline limits, the concentration of toxin must be
measured. The recommended maximum level for microcystin, a toxin produced by the
cyanobacterium Microcystis, in drinking water is 1.3 micrograms per litre (µg/L) (NHMRC001).
This is measured as microcystin-LR toxicity equivalents for other types of toxin. Higher
concentrations are hazardous and require actions to be taken to minimise the risk to human health.
Metals in lake waters
The NHMRC (1996) guidelines for the quality of untreated drinking water (Table 1) were applied
to concentrations of the metals iron, manganese and aluminium (Fe, Mn and Al) in the lakes.
However, where bulk water customers have site-specific standards for their WFPs, the SCA no
longer applies separate guidelines for metals in reservoirs.
6.2 Guidelines for delivery systems
The SCA strives to protect public health by monitoring the levels of a number of contaminants in
raw water that may be difficult to remove during conventional water treatment.
Drawn from nationally recognised standards for drinking water (NHMRC 1996), these
characteristics include the specific pesticides, heavy metals, chemicals and radiological substances
listed in Schedule 4 of the SCA Operating Licence (Table 2).
Site-specific standards for each WFP owned by Sydney Water are contained in the BWSA and are
shown in Table 1.
page 23
7 Key findings
7.1 Catchments
Catchment water quality was generally good. The main adverse impacts on water quality were
related to dissolved oxygen, nutrients and algal growth. Also, thermotolerant coliforms were
detected above guideline concentrations at a number of locations. Wet weather frequently resulted
in increased turbidity and thermotolerant coliform counts.
7.2 Reservoirs
Water quality in the reservoirs was generally good, although patterns of dissolved oxygen
depletion and elevated concentrations of metals indicated thermal stratification at a number of
locations. Guidelines were exceeded most frequently with respect to nutrients and algal growth.
Cyanobacteria concentrations in the Blue Mountains, Nepean and Woronora reservoirs were
mostly within the guidelines but were exceeded in other reservoirs more frequently. Toxigenic
cyanobacteria were rarely detected above guideline concentrations at any location, and positive
detection was limited to Lake Burragorang, Lake Yarrunga, Fitzroy Falls, Wingecarribee and
Prospect reservoirs.
7.3 Delivery systems
Water quality in the delivery systems (the water supplied to customers) was very good, with most
characteristics within Operating Licence and BWSA guideline levels. Some minor exceedances of
the guidelines for hardness were noted in the Warragamba, Nepean and Blue Mountains delivery
systems. Elevated pH was occasionally detected at Prospect, Nepean and Cascade WFPs. Minor
exceedances of the temperature guidelines were noted at the Macarthur WFP.
Algal counts were detected generally above BWSA guideline levels at Cascade and Greaves Creek
WFPs but only once at Macarthur WFP. The high algal counts were dominated by green algae and
large-celled diatoms, and these may have reduced filter run times, by clogging the filters, at the
affected WFPs.
7.4 Rivers downstream of reservoirs
Monitoring of temperatures downstream of reservoirs showed there was no impact in the
Hawkesbury-Nepean and Woronora rivers. Some impact was noted in the Shoalhaven River
immediately downstream of Tallowa Dam between November 2001 and January 2002.
7.5 Picnic area taps
Tap water quality in the picnic areas of Avon, Cataract, Cordeaux and Fitzroy Falls reservoirs was
generally satisfactory and had improved since 2000–2001. Tap water turbidity always complied
with guideline concentrations. Elevated levels of thermotolerant coliforms were detected at
Cataract picnic area on two occasions. The pH, which has no effect on human health at these
page 24
levels, was occasionally outside the guideline range at Cataract and Avon picnic areas. Colour was
always within guideline levels at Avon picnic area, while at Cataract, Cordeaux and Fitzroy Falls
this guideline was occasionally exceeded.
7.6 Special investigations, events and incidents
Bushfires
Special event monitoring was conducted in January and February 2002 to determine what impact
the Christmas 2001 bushfires and subsequent rainfall events had on water quality in the reservoirs
in the Sydney catchments. Post-event monitoring showed that there was little immediate risk to the
offtake water quality from runoff in bushfire-affected catchments, and this was attributed to the
relatively small inflow volume involved. Monitoring is continuing for any medium-term impacts.
Algal events
Algal samples from both the Greaves Creek and Cascade WFP inflows exceeded the maximum
1000 Area Standard Unit (ASU) specified in the BWSA on all occasions. The algae were
dominated by green algae and large-celled diatoms, which may have reduced filter run times by
clogging the water filters. Cyanobacteria in these reservoirs were rarely present above guideline
concentrations.
Algae exceeded the BWSA guideline at the Macarthur inflow (500 ASU) on one occasion only.
The observed value of 504 ASU was only marginally higher than the guideline value.
No algal events were noted at any of the other WFP inflows.
Wingecarribee Swamp monitoring
Wingecarribee Swamp immediately upstream of Wingecarribee Reservoir in the Southern
Highlands is an area of special interest to the SCA because:
the swamp potentially affects the quality of water stored in Wingecarribee Reservoir and
supplied to residents of the Southern Highlands, and
the Operating Licence requires the SCA to report annually on the implementation of the plan
of management for the area
peat swamps such as this are unusual in mainland Australia and Wingecarribee Swamp is
home to several species of rare plants and animals.
The upper Wingecarribee River has elevated nutrient levels (nitrogen and phosphorus) from
fertilisers washed into the river from agricultural land in the catchment.
The peat mass of Wingecarribee Swamp and upstream agricultural land contribute elevated total
nitrogen, total phosphorus and chlorophyll-a to the Wingecarribee River.
page 25
The reservoir does not tend to stratify, and metals concentrations remained below guidelines
throughout the year. No Schedule 4 substances were detected at Wingecarribee Reservoir.
Dissolved oxygen in the reservoir was depleted on 27 per cent of occasions, more frequently than
in 2000–2001. The pH was slightly above guideline concentration on all occasions (similar to
2000–2001). These measurements are consistent with the observed abundance of algal growth.
In the lower Wingecarribee River, turbidity and chlorophyll-a exceeded guideline concentrations,
suggesting that elevated nutrient levels are encouraging algal growth.
Water quality at the Wingecarribee WFP complied with Operating Licence conditions on all
occasions. Low levels of toxigenic cyanobacteria (microcystin-LR toxicity equivalents of 0.5
micrograms per litre or less, well below guideline levels) were detected from February 2002 to
June 2002.
Pesticide monitoring
No heavy metals, trace metals or pesticides were detected above guideline concentrations (for
pesticides, the guideline level is the detection limit) in any part of the Warragamba, Upper Nepean
or Woronora delivery systems in 2001–2002. No Schedule 4 substances were detected at either
Bendeela Pondage or Wingecarribee Reservoir.
In previous years the SCA has completed a number of studies of pesticide use including:
assessing levels of agricultural and industrial contaminants in inflows to major storages
reviewing and assessing sampling methods and monitoring program design for pesticides, and
assessing pesticide usage in SCA catchments.
Single (‘grab’) samples are unlikely to detect pesticides where these are present at very low
background levels or even when they occur in ‘spikes’ from specific events (such as rainfall, pest
or weed control operations, or dumping). Once in the system pesticides can settle or decompose.
The SCA has reviewed sampling methods for pesticides (Bales 2001) and has trialled lipid
samplers that can be left at a site to accumulate pesticides for up to four weeks at a time. This
method provides an indication of the different types of pesticides present in the water, but does not
enable estimation of their concentration. By integrating the fluctuations in trace levels that occur
over time, lipid samplers have detected pesticides in around one third of samples taken from
inflows to lakes Burragorang and Nepean.
These studies identify that contaminants are present in specific areas. However, the results cannot
readily be compared to guidelines as they are qualitative only. With further development, these
sampling techniques may be further refined to allow more effective monitoring of contaminants at
WFPs and greater assessment of the risks they pose.
page 26
Hotspots pathogen monitoring
The SCA has been conducting research into the source and distribution of pathogens within the
Sydney drinking water catchments as part of the ongoing Hotspots Program. Most human
pathogens are the result of faecal contamination of water supplies, and some pathogens can have
intermediate animal hosts.
This project examined the variation of sources of faecal contamination across the SCA area of
operations. It sampled raw water, sediment and treated sewage, as well as droppings from a range
of domestic, native and feral animals.
Overall, the results give a snapshot of pathogen levels across the catchments during dry weather.
They show that introduced, domestic or feral animals, and treated sewage effluent, rather than
native animals, are the major sources of pathogenic organisms in SCA catchments, with the types
of pathogen being broadly related to the source type. The next phase of the Hotspots Program will
address variations in pathogens over time.
Summary of water quality incidents
The SCA Corporate Incident Management Manual sets out the appropriate responses to incidents
which are classified according to risk from minor to emergency. Incidents can relate to water
quality, water supply or a number of other contingencies.
Between July 2001 and June 2002 the SCA logged a total of 27 incidents in relation to water
quality, (Table 4), one of which was classed as an emergency, three as major events, and the
remaining 23 as minor. The most serious incident occurred in March 2002 when monitoring
detected a high count of thermotolerant coliforms in a picnic area tap at Bendeela. Immediate
action was taken and resampling found the threat had diminished.
The number of incidents notified under each category is shown in Table 4. Full details of all
incidents, and the SCA's response and follow-up are outlined in Part 2 of this report.
Part 1 - Table 4: Summary of incidents
class
minor incident
number
23
Examples
unusual water quality characteristics such as high turbidity or pathogens in raw water
samples
major incident
3
thermotolerant coliforms detected in picnic area taps; WFP failure; cyanobacteria
detected
emergency
total
1
high levels of thermotolerant coliforms in picnic area taps and low residual chlorine
27
page 27
Wet weather events
The 2001–2002 monitoring year was dry until after the severe bushfires of December and January.
Runoff from a number of rainfall events – two in February, one in late March and a small event in
mid-April – was monitored to determine any impacts on catchment water quality.
Overall, wet weather samples had poorer water quality than dry weather samples, indicated by
higher median concentrations of most variables. Monitoring detected low levels of pathogens in
inflows to Lake Burragorang and Woronora Reservoir in wet weather samples taken after the
Christmas 2001 bushfires
Artificial aerators in Woronora, Nepean and Avon reservoirs were switched off in February after
heavy rain in the catchments.
8 Summary of results by system
This section summarises the performance of each delivery system and presents a graphical
summary of water quality indicating:
aesthetics (based on turbidity)
trophic level (based on phosphorus, chlorophyll or algal concentration)
health risk (based on thermotolerant coliforms), and
recreation (based on thermotolerant coliforms).
For each indicator at each site, the number of observations outside the guideline ranges was
expressed as a percentage of the total number of observations and assigned a colour as follows:
red: greater than 75 per cent
yellow: 50–75 per cent
green: 25–50 per cent
blue: less than 25 per cent.
The coloured icons on the following maps (figures 2 to 5) indicate water quality and its effect on
users across each delivery system.
page 28
8.1 Warragamba
Water quality in the Warragamba delivery system was very good, complying with Operating
Licence and BWSA conditions on all occasions for all parameters, with the exception of
occasional minor deviations from the hardness and pH guidelines and two detections of very low
levels of Cryptosporidium oocysts. Performance of key water quality indices is illustrated in
Figure 2.
Part 1 - Figure 2: Warragamba System – Performance of key water quality indices
8.2 Upper Nepean
Water quality in the Upper Nepean System was excellent, complying with the Operating Licence
and BWSA conditions on almost all occasions. The Illawarra Delivery System complied on all
occasions for all water quality characteristics.
At the Nepean WFP inlet there were infrequent exceedances of the pH and hardness guidelines
because of complications with the sampling procedure.
page 29
Minor exceedances of the temperature and algal guidelines were experienced at the Macarthur
WFP.
8.3 Woronora
Water supplied to the Woronora WFP during 2001–2002 met the standards specified in the
Operating Licence and BWSA on all occasions, as it did in 2000–2001.
Performance of key water quality indices for Upper Nepean and Woronora are illustrated in Figure
3.
Part 1 - Figure 3: Upper Nepean and Woronora Systems – Performance of key water quality
indices
page 30
8.4 Shoalhaven
Water quality at Shoalhaven and
Wingecarribee WFPs complied with
Operating Licence conditions on all
occasions. Performance of key water
quality indices is illustrated in Figure 4.
Part 1 - Figure 4: Shoalhaven System –
Performance of key water quality indices
8.5 Blue Mountains
Water quality in the Blue Mountains Delivery System
generally complied with Operating Licence and
BWSA guidelines except at Greaves Creek WFP
where algal numbers always exceeded the guideline
and hardness frequently exceeded the guideline by a
small margin. The pH guideline at Cascade WFP was
frequently exceeded by a very small margin.
Performance of key water quality indices is illustrated
in Figure 5.
Part 1 - Figure 5: Blue Mountains System –
Performance of key water quality indices
page 31
9 Trends in water quality
The SCA monitors long-term trends in the following key water quality characteristics at reservoir
offtake sites.
chlorophyll-a
total phosphorus
total nitrogen
dissolved oxygen, and
pH.
The trend analysis takes data from the 2001–2002 year and adds them to previous years. It uses a
statistical procedure called linear regression to determine the significance of any patterns. From
this analysis, several significant trends emerge.
Chlorophyll-a
Greaves Creek is the only reservoir where chlorophyll-a concentrations are increasing.
Chlorophyll-a primarily indicates the presence of algae.
Phosphorus and nitrogen
Total phosphorus (P) concentrations are decreasing in Lake Burragorang, Lower Cascade and
Nepean reservoirs, but are increasing at two locations in the Shoalhaven System: Tallowa Dam
and Fitzroy Falls.
Total nitrogen (N) is declining in Nepean and Woronora reservoirs but increasing in Cordeaux and
Lower Cascade reservoirs.
Both nutrients can stimulate algal and cyanobacterial blooms. The observed trends can be
explained by considering land use and rainfall patterns in the catchments.
Dissolved oxygen and pH
Dissolved oxygen saturation is decreasing in Nepean, Lower Cascade and Fitzroy Falls reservoirs
and increasing in Avon and Upper Cascade reservoirs.
Decreasing pH was apparent in Nepean Reservoir while increases were apparent in Avon,
Woronora, Greaves Creek, Lower Cascade and Upper Cascade.
Dissolved oxygen and pH can vary depending on a number of factors including algal
concentrations and operational activities such as artificial destratification.
page 32
10 Where to go for more information
More detailed information on the SCA’s water quality monitoring program can be found in Parts
2, 3 and 4 of the 2001-2002 Water Quality Report. This is available on the SCA’s website at
www.sca.nsw.gov.au.
11 References
ANZECC, 2000. National Water Quality Management Strategy. Australian and New
Zealand Guidelines for Fresh and Marine Water Quality. Australian and New
Zealand Environment and Conservation Council, Agriculture and Resource
Management Council of Australia and New Zealand.
Healthy Rivers Commission, 1998. Independent Inquiry into the Hawkesbury Nepean River
System. Final Report. Healthy River Commission of New South Wales.
NHMRC, 1996. Australian Drinking Water Guidelines. National Health and Medical
Research Council, Australia.
Research Council, Australia. Updated Fact Sheet 17a.
SACC, 2001. Media Release on Guidelines for Recreational Use of Water (January 2001),
Metropolitan/South Coast Regional Algal Coordinating Committee, Department of
Land and Water Conservation, NSW.
SCA, 1999. Sydney Catchment Authority and Sydney Water Corporation Bulk Water
Supply Agreement.
SCA, 2000. Bulk Water Quality Incident Response Plan. Sydney Catchment Authority,
Sydney.
SWC, 1999. Annual Environment and Public Health Report, 99. December 1999. Sydney
Water Corporation.
page 33
12 Glossary of terms
Word
Description
aesthetic
Considered pleasant to the senses
algae
Simple chlorophyll-bearing plants, most of which are aquatic and microscopic in
size
algal bloom
Rapid growth of algae in surface waters due to an increase in nutrients such as
nitrogen and phosphorus
alkalinity
The capacity to neutralise acid
analytes
Physical and chemical properties analysed
artificial destratification
The breakdown and mixing of layers in lakes using artificial means such as
aeration and propellers
catchment
Area where water is collected by the natural landscape. In a catchment, all rain
and run-off water eventually flows to a creek, river, lake or ocean, or into the
groundwater system.
chlorophyll
The green pigments in plants
composite sample
A sample made up of other samples or collected at more than one location
contaminant
Biological (e.g. bacterial and viral pathogens) and chemical introductions capable
of producing an adverse effect in a biological system
cyanobacteria
A division of photosynthetic bacteria, formerly known as blue-green algae, that
can produce strong toxins
cyanotoxin
Toxin produced by some cyanobacteria
detection limit
The smallest concentration or amount of a substance that can be reported as
present with a specified degree of certainty by definite complete analytical
procedures
DAPI
Confirmation test (for pathogens etc) using the 4’6-diaminidino-phenylindole
staining technique which targets DNA nucleic material
diurnal
Daily
dissolved oxygen
The amount of oxygen dissolved in water.
environmental flow
Water released from reservoirs aimed at improving and maintaining the
ecological health of the river downstream
epilimnion
The warmer upper layer of water in a stratified lake
eutrophication
The enrichment of a body of water with nutrients, resulting in a tendency for
excessive growth of algae
hardness
A measure of the concentration of calcium and magnesium ions in water,
frequently expressed as mg/L calcium carbonate equivalent (mg Ca Co3/L)
grab sample
A single sample collected at one location
hypolimnion
The cold lower layer of water in a stratified lake
indicator
A parameter that can be used to provide a measure of the quality of water or the
condition of an ecosystem
macrophyte
Large aquatic plant
mesotrophic
Water bodies or organisms which are intermediate between nutrient-rich and
nutrient-poor
morphometry
Characteristics of lakes that can be determined by simple measurements like
depth, volume and area
page 34
Word
Description
nutrients
Compounds required for growth by plants and other organisms. Major plant
nutrients are phosphorus and nitrogen
parameter
A measurable or quantifiable characteristic or feature
pathogens
Disease-causing organisms, such as bacteria and viruses
pH
A measure of the degree of acidity or alkalinity; expressed on a logarithmic scale
of 1 to 14
(1 is most acid, 7 neutral and 14 most alkaline)
physico-chemical
Refers to the physical (e.g. temperature, electrical conductivity) and chemical
(e.g. concentrations of nitrate, mercury) characteristics of water
phytoplankton
Small (often microscopic) aquatic plants suspended in water
potable water
Water suitable for drinking, on the basis of both health and aesthetic
considerations
reservoir
An artificial body of water, often behind a dam
sediment
Soil or other particles that settle to the bottom of lakes, rivers, and other waters
stratification
Arrangement of layers, especially of water having different physical or chemical
properties in lakes
surface storage
Reservoir
taxa
Any group of organisms considered to be sufficiently distinct from other such
groups to be treated as a separate unit (e.g. species, genera, families)
thermal stratification
The formation of distinct layers in lakes based on temperature
thermocline
A region of rapidly changing temperature in a lake, found between the epilimnion
and hypolimnion
thermotolerant coliforms
Bacteria used as a primary indicator of sewage pollution. Thermotolerant
coliforms may in some instances include bacteria of environmental rather than
faecal origin
toxicant
A chemical capable of producing an adverse response (effect) in a biological
system at concentrations that might be encountered in the environment, seriously
injuring structure or function or producing death. Examples include pesticides,
heavy metals and biotoxicants
toxigenic
Capable of producing toxins
toxin
A poisonous substance of biological origin
turbidity
A measure of the amount of suspended material (usually fine clay or silt
particles) in water and thus the degree of scattering or absorption of light in the
water
trophic status
Categorisation based on the level of algal growth and nutrient enrichment in a
lake eg oligotrophic (low algal growth and enrichment), eutrophic (high algal
growth and enrichment)
water column
The region of water between the surface and bottom of a lake or river
water filtration plant
A treatment plant that improves water quality by removing impurities through
filtration
water quality guideline
Scientific data evaluated to derive the recommended quality of water for various
uses
page 35
Acronyms used in this report
Acronym
Description
ASU
area standard unit
ANZECC
Australian and New Zealand Environment and Conservation Council
BWSA
Bulk Water Supply Agreement
cfu
colony forming units
DAPI
4’6-diaminidino-phenylindole
DMR
Department of Mineral Resources
DOS
dissolved oxygen saturation
EPA
Environment Protection Authority
HRC
Health Rivers Commission
IFA
immuno fluorescent antibody
NHMRC
National Health and Medical Research Council
NPWS
National Parks and Wildlife Services
NTU
nephelometric turbidity units
OC
organochlorine pesticide
PAC
percentage annual change
SACC
State Algal Co-ordinating Committee
SCA
SIEC
Sydney International Equestrian Centre
SRA
State Recreation Area
STP
sewage treatment plant
SWC
Sydney Water Corporation
WFP
water filtration plant
page 36
13 Contacting the SCA
The SCA's head office is in Penrith, and there are a number of field offices throughout the
catchments.
SCA Head Office, Penrith
Level 2, 311 High Street
Penrith NSW 2750
PO Box 323
Penrith NSW 2751
Phone: (02) 4725 2516
Fax: (02) 4732 3666
Office Hours: 9.30am - 5.00pm
Website: www.sca.nsw.gov.au
Email: [email protected]
EMERGENCY REPORTING
Report all fires, chemical and fuel spills
Phone: (02) 9751 1988 (24 hours)
FIELD OFFICE LOCATIONS
Goulburn Office
Moss Vale Office
Newo House
Shop 1
23-25 Montague Street
Old Argyle Centre
Goulburn NSW 2580
256 Argyle Street
Phone: (02) 4823 4200
Moss Vale NSW 2577
Fax: (02) 4822 9422
Phone: (02) 4868 0300
Hours: 8.00am to 4.00pm
Fax: (02) 4868 0306
Wednesday and Thursday
Braidwood Office
Operational Offices
Park Lane
Cordeaux Dam
Braidwood NSW
Warragamba Dam
Phone: (02) 4842 9400
Kenny Hill
Fax: (02) 4842 9402
Burrawang
Blue Mountains
ISSN: 1446-2028
page 37
Part 2: Monitoring for the Operating Licence
Acknowledgements:
page 2
Contents
1
5
2
About this report
5
3
Monitoring for the Operating Licence
6
4
5
6
7
3.1
Warragamba delivery system
6
3.2
Nepean and Macarthur delivery system
6
3.3
Illawarra and Woronora delivery system
6
3.4
Blue Mountains delivery system
6
3.5
Other delivery systems
7
Relevant water quality guidelines
7
4.1
Compliance monitoring for drinking water guidelines
7
4.2
Compliance Monitoring for the Bulk Water Supply Agreement (BWSA)
7
Data analysis
10
5.1
Data collation
10
5.2
Statistics and comparison with guidelines
10
5.3
Trend analysis
11
Results and discussion
14
6.1
Warragamba Delivery System
14
6.2
Upper Nepean System
16
6.3
The Woronora Delivery System
17
6.4
The Blue Mountains Delivery System
19
6.5
The Shoalhaven Scheme
21
Special investigations, events and incidents
23
7.1
Bushfires
23
7.2
Algal events
23
7.3
Wingecarribee Swamp monitoring
24
7.4
Pesticide monitoring
25
7.5
Hotspots pathogen monitoring
27
7.6
28
page 3
7.7
8
9
Wet weather events
29
Protecting public health
30
8.1
30
The SCA – protecting public health
References
32
page 4
supply.
The SCA’s task is to supply quality bulk raw water to its customers, which include Sydney Water
and a number of local councils in the Southern Highlands, Illawarra and the Shoalhaven. These
customers then filter and distribute the water to nearly four million people - about 60 per cent of
NSW's population.
2 About this report
This report is Part 2 of the Sydney Catchment Authority’s annual water quality monitoring report,
2001–2002. It details technical results for the monitoring program undertaken to meet the
requirements of the SCA’s Operating Licence.
In other parts of the annual water quality monitoring report:
2001 to June 2002.
purposes.
page 5
3 Monitoring for the Operating Licence
The Sydney Catchment Authority’s Operating Licence requires water quality in reservoirs to
comply with National Health & Medical Research Council (NHMRC) Australian Drinking Water
Guidelines (1996) with respect to iron, manganese and aluminium (Part 2 - Table 1). It also
defines health guidelines for water characteristics that may be difficult to remove during water
treatment (Part 2 - Table 2). Additionally, the Bulk Water Supply Agreement (BWSA) between
the SCA and Sydney Water sets limits for characteristics such as turbidity, alkalinity and colour,
which in turn determine the treatability of the water.
3.1 Warragamba delivery system
The SCA monitors water quality at the inlets to three water filtration plants (WFPs) in the
Warragamba delivery system. These are Warragamba, Orchard Hills and Prospect WFPs.
Hardness exceeded BWSA guideline levels occasionally at all three locations but only by 8 mg
CaCO3/litre or less. The pH exceeded guidelines by up to one pH unit at Prospect on only three
occasions.
3.2 Nepean and Macarthur delivery system
The Upper Nepean system delivers water to the Nepean and Macarthur WFPs. Hardness and pH
guidelines were exceeded twice at the Nepean WFP inlet, possibly because of sampling procedure
complications. Water temperature exceeded the guideline on a few occasions and algal
concentrations increased just above guideline levels once at Macarthur WFP.
3.3 Illawarra and Woronora delivery system
The quality of water supplied to the Illawarra and Woronora WFPs complied with both the
Operating Licence and the BWSA guidelines on all occasions.
3.4 Blue Mountains delivery system
The Blue Mountains delivery system supplies water to Greaves Creek and Cascade WFPs. On a
few occasions, hardness exceeded the guideline marginally at Greaves Creek WFP and pH
page 6
exceeded the guideline at Cascade WFP. Algal counts at these WFPs were generally above the
guideline. The high algal counts were dominated by green algae and large-celled diatoms rather
than cyanobacteria (also called blue-green algae) and consequently their impact would have been
limited to a reduction of filter run times.
3.5 Other delivery systems
The Shoalhaven Council-owned WFP servicing Kangaroo Valley and the Wingecarribee WFP are
not covered by a BWSA but the water supplied to them complied with the Operating Licence
(Schedule 4 requirements) on all occasions.
4 Relevant water quality guidelines
4.1 Compliance monitoring for drinking water guidelines
Under the terms of its Operating Licence, the SCA monitors water quality in the catchments and
reservoirs (Part 2 - Table 1). The SCA monitors water delivered to its customers for the
characteristics listed in Part 2 - Table 2 which includes substances not substantially removed or
reduced by water treatment processes.
4.2 Compliance Monitoring for the Bulk Water Supply Agreement
(BWSA)
The BWSA between the SCA and Sydney Water sets site-specific standards at each WFP for
characteristics such as turbidity, alkalinity and colour, all of which determine the treatability of the
water. The standards vary between WFPs because of differences in WFP design and in water
chemistry between source catchments. Table 1 lists the guidelines applying to each WFP.
page 7
Part 2 - Table 1: Water quality guidelines applying to the SCA’s water delivery network
Analytes (Unit)
Catchment
o
Temperature ( C)
na
Storage
Reservoirs
(Lake)
na
Delivery System (site-specific guidelines)
Prospect
Warragamba
Orchard Hills
Macarthur
Nepean
Illawarra
Woronora
Cascade
Greaves Ck
10.0–23.6
8.8–24.1
8.0–25.0
10.0–25.0
10.0–26.6
5.0–24.0
5.0–25.0
90–110
90–110
na
na
na
na
na
na
na
pH (pH unit)
6.5-8.0
6.9-8.1* (LB)
6.0-7.2** (O)
6.27–7.87
5.72–7.65
4.80-7.65
6.15–7.20
5.06–7.54
6.00-7.40
4.40-9.20
Alkalinity (mg CaCO3/L)
na
na
21–45
0.8–14
0.5–45
0.6–7.6
0.5–12.5
0.5–31
0.5–10
Hardness (mg CaCO3/L)
na
na
28.5–53.5
6.4–32.2
2.1–30
5.2–23
2.6–22.8
40
1.5–6.6
Turbidity (NTU)
25
20
40
60
183
10
11
15
40
True Colour (CU)
na
na
60
40
60
48
70
60
60
Total Iron (mg/L)
na
0.3
3.5
1.3
5
1.12
1.0
3.0
2.8
na
0.1
1.40
0.35
1.45
0.37
0.07
0.25
1.00
na
0.2
2.58
0.95
1.00
1.401
0.4
0.18
1.00
0.050
0.010
na
na
na
na
na
na
na
0.50
0.35
na
na
na
na
na
na
na
150
100
na
na
na
na
na
na
na
Enterococci (CFU/100 mL)
na
na
na
na
na
na
na
na
na
7
5
na
na
na
na
na
na
na
Algal ASU (per mL)
na
na
1000
500
1000
5000
5000
1000
1000
na
15000
na
na
na
na
na
na
na
na
2000
na
na
na
na
na
na
na
(mm2/L)
na
2
na
na
na
na
na
na
na
Notes: * LB = Lake Burragorang and Prospect Reservoir; ** O = other lakes. na = not applicable
page 8
Part 2 - Table 2
Guidelines for trace elements and contaminants (for Sydney Water WFPs only)
Analyte
Guideline
Unit
Total Arsenic
0.007
mg/L
Total Barium
0.7
mg/L
Total Boron
0.3
mg/L
Total Mercury
0.001
mg/L
Total Molybdenum
0.05
mg/L
Total Selenium
0.01
mg/L
Total Silver
0.1
mg/L
Iodide
0.1
mg/L
Aldrin
3.0
µg/L
Amitrole
1.0
µg/L
Atrazine
20.0
µg/L
1.0
µg/L
Chlordane
2.0
µg/L
1000.0
µg/L
2 4-Dichloro-phenoxy-acetic acid
30.0
µg/L
DDT
20.0
µg/L
Dieldrin
0.3
µg/L
Diquat
5.0
µg/L
Diuron
30.0
µg/L
Total Endosulfan
30.0
µg/L
Chlorpyrifos
Clopyralid
0.3
µg/L
300.0
µg/L
Lindane
20.0
µg/L
Molinate
5.0
µg/L
Paraquat
30.0
µg/L
Picloram
300.0
µg/L
Propiconazole
100.0
µg/L
Temephos
300.0
µg/L
Heptachlor
Hexazinone
10.0
µg/L
Gross Alpha emitters
0.1
Bq/L
Gross Beta emitters
0.5
Bq/L
Triclopyr
Source: NHMRC (1996); Schedule 4 of the SCA Operating Licence
page 9
5 Data analysis
5.1 Data collation
Data collected between July 2001 and June 2002 were consolidated prior to analysis by extracting
them from SCA’s water quality databases. A list of sampling locations and their site codes is
provided in Appendix A.
The dataset from catchment sites was divided into two categories based on the flow at the time of
sampling:
wet weather and
dry weather.
The data from reservoirs represented water samples taken as:
grab samples from specific depths in the water column
single composite samples representative of the surface layer (epilimnion) or
both grab and composite samples.
The data used in the analysis represented either grab samples from three metres depth or composite
samples from the epilimnion. This collation enabled long-term trends to be compared with
guidelines.
Throughout the year, samples were tested for Cryptosporidium oocysts and Giardia cysts using a
two-stage identification process of Immuno Fluorescent Antibody (IFA) followed by exposure to
diaminidino-phenylindole (DAPI). The consensus from experts after Sydney’s 1998 water quality
crisis was that water authorities should act only when detected oocysts or cysts take up both stains,
a convention observed throughout this report. In other words, Cryptosporidium and Giardia results
are given for oocysts and cysts which stained first by IFA and then by DAPI.
5.2 Statistics and comparison with guidelines
Part 1 of this report presents graphical summaries of water quality throughout the supply system
(Figures 2 to 5). Appendix B presents a summary of statistics for each water quality variable as a
box plot while Appendix C presents a summary table of data for each monitoring site within the
system.
page 10
5.3 Trend analysis
5.3.1
Long-term trends
Five key water quality variables measured at each reservoir offtake site since 1990 were analysed
for trends using linear regression. These were:
chlorophyll-a
total phosphorus
total nitrogen
dissolved oxygen and
pH.
The results are summarised in Table 3. For those sites where a significant trend was detected, the
table lists the typical annual change and standard error relative to this change. Values are given in
the units in which that variable is reported throughout this report. Positive trend values indicate
rising levels, while negative trend values indicate falling levels. Table 4 shows the actual change in
median value for each of the variables, over the last three years.
5.3.2
Chlorophyll-a
A significant trend in chlorophyll-a concentration was detected only at Greaves Creek (DGC1)
where a gradual annual increase was apparent. This has not been accompanied by significant
trends in nutrient concentration.
5.3.3
Nutrients – total phosphorus and total nitrogen
Trends in nutrient concentrations in reservoirs are affected by the water quality of inflows, which
in turn is determined by land use in the catchments. Rainfall patterns (frequency and intensity) will
also affect the amount and timing of nutrient input into the reservoirs.
Total phosphorus concentrations are decreasing in Lake Burragorang (DWA2), Lower Cascade
(DLC1) and Nepean (DNE2) reservoirs but are increasing at two locations in the Shoalhaven
System: Tallowa Dam (DTA1) and Fitzroy Falls (DFF6). Other reservoirs showed no significant
trends in total phosphorus concentration.
Total nitrogen is declining in Nepean (DNE2) and Woronora (DWO1) reservoirs but increasing in
Cordeaux (DCO1) and Lower Cascade (DLC1) reservoirs. Other reservoirs showed no significant
trends in total nitrogen concentration.
page 11
Part 2 - Table 3 Long-term water quality trends in SCA reservoirs 1990–2002
System
Site
Warragamba
Upper Nepean
& Woronora
Blue Mountains
Shoalhaven
Chlorophyll-a
Total P
Total N
DO
µg/L
mg/L
mg/L
% saturation
DWA2
nst
-0.0008 ± 0.0004
nst
nst
nst
RPR1
nst
nst
nst
nst
nst
DNE2
nst
-0.003 ± 0.001
-0.017 ± 0.003
-1.57 ± 0.78
-0.044 ± 0.027
DAV7
nst
nst
nst
0.67 ± 0.34
0.030 ± 0.016
DCO1
nst
nst
0.006 ± 0.002
nst
nst
DCA1
nst
nst
nst
nst
nst
DWO1
nst
nst
-0.002 ± 0.001
nst
0.044 ± 0.013
DGC1
0.25 ± 0.09
nst
nst
nst
0.085 ± 0.019
DLC1
nst
-0.002 ± 0.001
0.005 ± 0.002
-0.40 ± 0.16
0.062 ± 0.020
DTC1
nst
nst
nst
0.77 ± 0.37
0.074 ± 0.029
DTA8
nst
0.0013 ± 0.0005
nst
nst
nst
DFF6
nst
0.0002 ± 0.0001
nst
-0.26 ± 0.11
nst
DWI1
nst
nst
nst
nst
nst
nst
No Significant Trend
5.3.4
pH
The interpretation of trends for dissolved oxygen saturation and pH is more difficult. Both
characteristics can vary from day to day, and fluctuate depending on time of day, amount of
daylight, the presence of algae and other factors. Over the longer term they are affected by
operational activities such as artificial destratification.
Nevertheless, the measured dissolved oxygen saturation has been decreasing in Nepean (DNE2),
Lower Cascade (DLC1) and Fitzroy Falls (DFF6) reservoirs and increasing in Avon (DAV7) and
Upper Cascade (DTC1) reservoirs.
Significant trends in pH were found for reservoirs in the Upper Nepean, Woronora and Blue
Mountains systems. Decreasing pH was apparent in Nepean (DNE2) Reservoir while increases
were apparent in Avon (DAV7), Woronora (DWO1), Greaves Creek (DGC1), Lower Cascade
(DLC1) and Upper Cascade (DTC1). Water transfers from other reservoirs such as Oberon,
together with artificial destratification, may be increasing pH values in Blue Mountains reservoirs.
page 12
Part 2 - Table 4 Yearly comparison on median values of each water quality variables
System
Warragamba
Site
DWA2
RPR1
Upper Nepean
DNE2
& Woronora
DAV7
DCA1
DCO1
DWO
1
Blue
DGC1
Mountains
DLC1
DTC1
Shoalhaven
DTA8
DFF6
DWI1
Thermotolerant
coliforms
Turbidity
Chlorophyll-a
Total N
Total P
(NTU)
(µg/L)
(mg/L)
(mg/L)
1999-00
1.1
2.9
0.33
0.007
1
2000-01
0.9
2.5
0.28
0.006
1
2001-02
1.7
2.3
0.26
0.004
0
1999-00
1.6
3.0
0.31
0.006
2
2000-01
1.6
2.8
0.26
0.006
1
2001-02
1.7
2.5
0.27
0.006
1
1999-00
2.0
3.5
0.39
0.009
1
2000-01
1.6
3.2
0.35
0.009
0
2001-02
1.7
2.0
0.33
0.007
1
1999-00
1.0
5.1
0.23
0.006
1
2000-01
1.3
4.9
0.20
0.006
1
2001-02
1.5
3.3
0.20
0.005
0
1999-00
1.7
4.7
0.22
0.005
1
2000-01
1.1
3.9
0.20
0.005
0
2001-02
1.5
4.0
0.24
0.006
1
1999-00
2.3
5.7
0.28
0.009
2
2000-01
1.5
5.5
0.24
0.006
1
2001-02
2.0
4.7
0.29
0.007
0
1999-00
1.7
1.3
0.22
0.004
1
2000-01
1.1
1.0
0.22
0.004
0
2001-02
1.5
1.4
0.21
0.004
0
1999-00
2.1
3.3
0.20
0.008
2
2000-01
1.6
2.2
0.20
0.007
3
2001-02
2.0
5.3
0.17
0.004
5
1999-00
1.7
2.5
0.25
0.005
3
2000-01
1.6
2.3
0.25
0.006
4
2001-02
1.6
1.7
0.26
0.003
4
1999-00
1.5
5.2
0.35
0.007
4
2000-01
1.5
6.8
0.32
0.009
2
2001-02
1.5
5.0
0.34
0.007
4
1999-00
5.1
11.6
0.35
0.023
69
2000-01
4.1
6.8
0.32
0.022
22
2001-02
5.3
6.8
0.37
0.023
54
1999-00
3.4
6.5
0.42
0.014
1
2000-01
2.8
5.7
0.36
0.014
0
2001-02
4.0
10.7
0.50
0.014
1
1999-00
4.4
8.2
0.39
0.016
2
2000-01
2.8
5.7
0.35
0.015
1
2001-02
4.7
6.8
0.44
0.015
4
Year
page 13
(CFU/100ml)
6 Results and discussion
6.1 Warragamba Delivery System
The Warragamba Delivery System (Figure 1) consists of large-diameter pipes which transport
water by gravity from Lake Burragorang to WFPs at Warragamba, Orchard Hills and Prospect.
The water is monitored in the pipelines and at the inlets to the treatment plants.
Overall, the quality of the raw water supply from the Warragamba delivery system was very good,
almost totally satisfying BWSA specifications. No heavy metals, trace metals or pesticides were
detected above Operating Licence guideline concentrations in any part of the Warragamba
delivery system.
At the Warragamba and Orchard Hills WFP inlets (HWA1, HBR1), hardness was the only variable
to exceed guideline concentrations. One sample at Warragamba (HWA1) and two at Orchard Hills
(HBR1) had hardness above the guideline value of 53.5 mg CaCO3/litre. In both cases, the
maximum hardness observed was 60 mg CaCO3/litre, which is only slightly above the guideline
maximum. In 2000–2001 no samples from Warragamba and one from Orchard Hills exceeded the
hardness guideline concentration.
At the Prospect WFP inlet (PWFP1) hardness marginally exceeded the guideline of 53.5 mg
CaCO3/litre in one sample, with a concentration of 61 mg CaCO3/litre. The pH was above the
guideline maximum (7.87) on 25 per cent of occasions (three samples), with a maximum pH of
8.9. No samples exceeded the alkalinity guideline. The frequency of guideline exceedance for
alkalinity and hardness in 2001–2002 was lower than in 2000–2001 while the frequency of pH
exceeding the guideline was greater. There were no public health implications from any of these
exceedances.
Algal counts were always within guideline levels.
The SCA maintains close cooperation with SWC in the monitoring of pathogens in the water
supply system. During the period October to December 2001, there were fifteen low level positive
detections of Cryptosporidium oocysts in the inflows to Prospect WFP by SWC. There were
however, no positive detections of Cryptosporidium oocystsin the filtered water. The results were
referred to NSW Department of Health, who advised that there was no risk to public health. An
independent review of the results was commissioned by the SCA, which also concluded that the
observed results would be categorised as normal.
page 14
Part 2 - Figure 1 Warragamba System and monitoring sites
page 15
6.1.1
Performance assessment
Water quality in the Warragamba delivery system was very good, complying with Operating
Licence and BWSA conditions on all occasions for all parameters, with the exception of
occasional minor deviations from the hardness and pH guidelines and a number of detections of
very low levels of Cryptosporidium oocysts.
6.2 Upper Nepean System
6.2.1
Nepean Delivery System
Nepean Reservoir supplies water to the Nepean WFP (HNE1) (Figure 2). Cataract, Cordeaux and
Nepean dams feed Macarthur (HUC1) and Prospect (PWFP1) WFPs. The Nepean WFP supplies
drinking water to the surrounding rural area and the local townships of Bargo, Thirlmere, Picton
and The Oaks. The privately owned and operated Macarthur WFP, under contract to Sydney
Water, supplies drinking water to the Camden, Campbelltown and Wollondilly local government
areas sourced from the Upper Canal Delivery System at Broughtons Pass Weir. The Prospect
WFP, partially supplied from the Upper Canal, is considered part of the Warragamba delivery
system, discussed above.
At the Nepean WFP inlet (HNE1), pH and hardness exceeded guideline maximum values (7.65 pH
units and 30.0 milligrams CaCO3/litre respectively) on two occasions, reaching pH 10.5 and 42.5
mg CaCO3/litre. These values were probably caused by raw water which is treated with lime
before filtration; the partially treated water can backflow from the oxidation tanks via the rising
main. Sampling protocols will be changed to ensure that future samples are collected once the
plant has been operating for a reasonable time.
Water quality at the Macarthur WFP inlet (HUC1) was very good, except for a minor instance in
which temperature exceeded the guideline maximum of 24.1°C by 1°C, and algae exceeded the
guideline of 500 ASU by 4 ASU. These minor exceedances posed no health risk to consumers.
Temperature did not exceed the guidelines in 2000–2001. Minor exceedances of the colour and
total iron guidelines observed in 2000–2001 were not repeated in 2001–2002.
page 16
6.2.2
Illawarra Delivery System
The Illawarra Delivery System (Figure 2) transports water from the upper reaches of Avon
Reservoir by gravity and, in drought times, pumping, to the Illawarra WFP. The water quality in
the delivery system is monitored at the inlet of the WFP (IWFPR).
The quality of water supplied to the Illawarra WFP was satisfactory, complying with the Operating
Licence and BWSA at all times.
6.2.3
Water quality in the Upper Nepean System was excellent, complying with the Operating Licence
and BWSA conditions on almost all occasions. The Illawarra Delivery System complied on all
occasions for all water quality characteristics.
At the Nepean WFP inlet there were infrequent exceedances of the pH and hardness guidelines,
apparently because of complications with the sampling procedure.
Minor exceedances of the temperature and algal guidelines were experienced at the Macarthur
WFP.
6.3 The Woronora Delivery System
The Woronora Delivery System is a pipe system that transfers water from the Woronora Reservoir
to the Woronora WFP. Water quality in the system is monitored at the WFP inlet (HWO1).
Water supplied to the Woronora WFP during 2001–2002 met the standards specified in the
Operating Licence and BWSA on all occasions, as it did in 2000–2001.
Water supplied to the Woronora WFP met the standards specified in the Operating Licence and
BWSA on all occasions in 2001–2002.
page 17
Part 2 - Figure 2
Nepean and Woronora Systems and monitoring sites
page 18
6.4 The Blue Mountains Delivery System
The Blue Mountains Delivery System (Figure 3) is a complex network of pipes that can deliver
water from both within and outside the Blue Mountains catchments. Greaves Creek WFP
(HGC01) is typically supplied from Greaves Creek Reservoir, with the option for additional
supply from Lake Medlow. The Cascade WFP (HCSR) is supplied from the Cascade storages,
supplemented with water from the Oberon Reservoir, part of the Fish River Water Supply Scheme.
Water supplied to the Greaves Creek WFP was generally of good quality, except that hardness
frequently exceeded the guideline maximum by up to 5 mg CaCO3/litre, a minor amount. Water
supplied to the Cascade WFP was also of generally good quality, but pH frequently exceeded the
guideline maximum of pH 7.4 by up to 0.1 pH units.
Algal counts, dominated by green algae and large-celled diatoms rather than cyanobacteria, were
above the guideline 1000 ASU on all occasions at both Greaves Creek and Cascade WFPs. The
presence of these organisms in abundance above the guidelines is expected to have reduced the
filter run times at these WFPs.
6.4.1
Water quality in the Blue Mountains Delivery System generally complied with Operating Licence
and BWSA guidelines except at Greaves Creek WFP where algal numbers always exceeded the
guideline and hardness frequently exceeded the guideline by a small margin. The pH guideline at
Cascade WFP was frequently exceeded by a very small margin.
There were no public health implications from any of these exceedances as they were all recorded
in the untreated water.
page 19
Part 2 - Figure 3 Blue Mountains System and monitoring sites
page 20
6.5 The Shoalhaven Scheme
6.5.1
Shoalhaven Delivery Systems
The Shoalhaven System includes the Shoalhaven Scheme, an engineered network of dams, canals
and pipelines, built to transfer water from the catchments of the Shoalhaven River to Sydney
during times of drought. Power generation involves regular exchange of stored waters between
Lake Yarrunga, Bendeela Pondage and Fitzroy Falls Reservoir. All the water quality monitoring
sites in the catchments and reservoirs of the Shoalhaven System are illustrated in Figure 4.
The Bendeela Pondage (DBP1) is a very small impoundment in the delivery system connecting
Lake Yarrunga with Fitzroy Falls Reservoir. The water supply for the residents of Kangaroo
Valley is drawn from here. Raw water is treated at a WFP operated by Shoalhaven City Council.
Wingecarribee Reservoir supplies water to Wingecarribee WFP (HWI1), which supplies many
residents of the Southern Highlands with drinking water.
The Operating Licence specifies monitoring for Schedule 4 substances (pesticides, heavy metals,
chemical and radiological substances). There were no detectable levels of Schedule 4 substances at
either Bendeela Pondage or Wingecarribee Reservoir.
6.5.2
Water quality at Shoalhaven and Wingecarribee WFPs complied with Operating Licence
conditions on all occasions.
page 21
Part 2 - Figure 4 Shoalhaven System and monitoring sites
(
0
10
HWI1
20
Kilometres
DTA3
DTA10
DTA8
Lake site
DTA1
Catchment site
Delivery System Site
DWI1
DFF6
DBP1
E706
Kangaroo Rv
Rv
Kangaroo
DTA5
E847
R
S
S
SH
H
S
S
HO
O
H
H
OA
A
A
O
O
L
AL
A
A
IVE
H
H
LH
LH
LH
LL
LLH
A
A
HA
H
H
V
V
E
E
AV
A
A
N
N
VE
V
V
E
EN
E
N
N R
N
NNeerrr
iimmuu
nnggaa
CCkk
Jervis
Bay
E890
GGilillalam
maato
tonngg CC
kk
Moonngg
M
aarrloloww
ee RRvv
CCkk
ddyy
Reeee
vv
gg RR
rraann
CCoo
CCkk
rroo
BBoo
E8311
E822
E891
E860
Nowra
Braidwood
Braidwood
JJeemm
bbaaii
ccuumm
bbeenn
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kk
page 22
7 Special investigations, events and incidents
7.1 Bushfires
Special event monitoring was conducted in January and February 2002 to determine what impact
the bushfires in December 2001 and January 2002 and subsequent rainfall events had on water
quality in the reservoirs in the Sydney catchments. Post-event monitoring showed that there was
little immediate risk to the offtake water quality from runoff in bushfire-affected catchments, and
this was attributed to the relatively small inflow volume involved.
The main impacts observed were increased turbidity, increased true colour and some additional
influx of debris. Water entering the reservoirs was frequently cooler and more turbid than the
stored water and tended to form a layer under the warm, clear surface waters. The turbid inflows
occasionally reached the dam wall but generally remained below offtake levels and so did not
impact the quality of water supplied to the WFPs. At Woronora Reservoir, the catchment most
affected by the bushfires, operators avoided turbid water close to the offtake level by closing the
east outlet and opening the (higher) west outlet.
Monitoring detected Escheria coli and Clostridium perfringens at high levels in inflows to Lake
Burragorang and Woronora Reservoir in early January 2002. This result indicated possible faecal
contamination of runoff from bushfire-affected areas. E. coli at Woronora exceeded the Minor
Incident Event Level specified in the SCA Bulk Water Quality Incident Response Plan (2001).
Particulate iron levels were also found to be elevated in inflows (Woronora River, Bee Creek and
Honeysuckle Creek inflows) to Woronora Reservoir.
7.2 Algal events
As reported earlier, at both the Greaves Creek and Cascade WFP inflows, algal samples exceeded
the maximum 1000 ASU specified in the BWSA on all occasions. The algae were dominated by
green algae and large-celled diatoms, which may have reduced filter run times by clogging the
water filters. Cyanobacteria in these reservoirs were rarely present above guideline concentrations.
Algae exceeded the BWSA guideline at the Macarthur (HUC1) inflow (500 ASU) on one occasion
only. The observed value of 504 ASU was only marginally higher than the guideline value.
No algal events were noted at any of the other WFP inflows.
page 23
7.3 Wingecarribee Swamp monitoring
Wingecarribee Swamp near Robertson in the Southern Highlands lies on the Wingecarribee River
immediately upstream of Wingecarribee Reservoir (DWI1), a shallow storage reaching a
maximum depth of 12 metres. The reservoir supplies water to Wingecarribee WFP (HWI1), which
in turn supplies many residents of the Southern Highlands with drinking water.
Wingecarribee Swamp is an area of special interest to the SCA for statutory, operational and
ecological reasons:
the Operating Licence requires the SCA to report annually on the implementation of the plan
of management for the area
the swamp potentially affects the quality of water stored in Wingecarribee Reservoir and
supplied to residents of the Southern Highlands, and
peat swamps such as this are unusual in mainland Australia and Wingecarribee Swamp is
home to several species of rare plants and animals.
Wingecarribee Swamp suffered a collapse in 1998 after heavy rains washed a large section into
Wingecarribee River, permanently altering the swamp's sensitive peatland ecosystem.
Responsibility for the swamp was transferred to the SCA when it began operations in 1999. The
swamp is now jointly managed by the SCA and National Parks and Wildlife Service (NPWS) as
part of the Wingecarribee Swamp and Special Areas Strategic Plan of Management.
Wingecarribee Reservoir, which is downstream of the swamp, was also affected when a significant
amount of peat and sedimentary material was washed into the reservoir as a result of the collapse.
As part of the plan of management, ongoing water quality monitoring is conducted at several sites
in the swamp, using both physical and chemical water quality indicators, to determine the effect of
the swamp collapse on stream flow and groundwater inputs to the reservoir.
This section of the report summarises water quality monitoring in the Wingecarribee catchment in
2001–2002. The SCA has made available a comprehensive annual report on the broader
implementation plan for the swamp.
page 24
7.3.1
Results
The upper Wingecarribee River experiences elevated nutrient levels from fertilisers used in the
catchment, although monitoring in Wingecarribee Swamp suggests the swamp is filtering
thermotolerant coliforms, nitrogen and phosphorus.
The peat mass of Wingecarribee Swamp and upstream agricultural land uses contribute to elevated
total nitrogen, total phosphorus and chlorophyll-a in the Wingecarribee River, and most likely
explain the observed water quality impacts.
In the reservoir itself, the Operating Licence specifies monitoring for Schedule 4 substances (Part
2 - Table 2). Being shallow, the reservoir is not prone to thermal stratification, and so metals
concentrations remained below guidelines throughout the year and no Schedule 4 substances were
detected at Wingecarribee Reservoir.
Dissolved oxygen in the reservoir was depleted on 27 per cent of occasions, more frequently than
in 2000–2001, and pH was elevated slightly above guideline concentration on all occasions
(similar to 2000–2001). These measurements are consistent with the observed abundance of algal
growth.
In the lower Wingecarribee River (E332), turbidity and chlorophyll-a exceeded guideline
concentrations, suggesting that elevated nutrient levels are encouraging algal growth, with
consequent consumption of dissolved oxygen and elevation of pH.
Water quality at the Wingecarribee WFP complied with Operating Licence conditions on all
occasions. However, nutrient levels were high, with total nitrogen exceeding the guideline
concentrations on 90 per cent of occasions and total phosphorus exceeding guidelines on all
occasions. Chlorophyll-a and cyanobacteria exceeded guidelines on 82 per cent and 96 per cent of
occasions respectively. Low levels of toxigenic cyanobacteria (microcystin-LR toxicity
equivalents of 0.5 micrograms per litre or less, well below guideline levels) were detected from
February 2002 to June 2002.
7.4 Pesticide monitoring
The SCA strives to protect public health by monitoring levels of a number of contaminants in raw
water that may be difficult to remove during conventional water treatment and that may therefore
affect water quality at the consumer’s tap.
Drawn from nationally recognised standards for drinking water (NHMRC 1996), these
characteristics include the specific pesticides, heavy metals, chemicals and radiological substances
listed in Schedule 4 of the SCA Operating Licence (Part 2 - Table 2).
page 25
The results of the water quality monitoring program show that no heavy metals, trace metals or
pesticides were detected above guideline concentrations (for pesticides, the detection limit is the
guideline level) in any part of the Warragamba delivery system in 2001–2002.
No Schedule 4 substances were detected at either Bendeela Pondage or Wingecarribee Reservoir.
In previous years the SCA has completed a number of studies of pesticide use, including:
assessing levels of agricultural and industrial contaminants in inflows to major storages
reviewing and assessing sampling methods and monitoring program design for pesticides
assessing usage of pesticides in SCA catchments.
These specific investigations have detected pesticides in around one-third of samples taken from
inflows to lakes Burragorang and Nepean. These trials compared different models of passive
samplers that were left in place for four weeks to accumulate pesticides. This method provides an
indication of the type of pesticides but does not enable estimation of their concentration. Grab
samples taken over the same time period failed to detect pesticides in many cases. The different
results of each sampling method (passive versus grab) occur because contaminants:
are present at very low background levels
appear as ‘spikes’ from specific events (such as rainfall, specific pest or weed control
operations, or even dumping)
become integrated over time into the passive samplers, and
can settle or decompose.
These studies identify that contaminants are present in specific areas, but the results cannot readily
be compared to guidelines because they are only qualitative. With research and development these
sampling techniques may be further refined to allow more effective monitoring of contaminants at
WFPs and greater assessment of the risks posed by contaminants.
page 26
7.5 Hotspots pathogen monitoring
The SCA has been conducting research into the source and distribution of pathogens within the
Sydney drinking water catchments, as part of the ongoing Hotspots Program. Most human
pathogens are the result of faecal contamination of water supplies, and some pathogens can have
intermediate animal hosts.
This project examined the spatial variation of sources of faecal contamination across the SCA area
of operations. It sampled raw water, sediment and treated sewage, as well as faeces from a range
of domestic, native and feral animals.
The sampling period for this project covered the period from late autumn to early winter 2002, a
period with little or no rainfall in the catchment.
Faeces from domestic animals contained higher levels of bacteria, viruses and pathogenic
protozoans compared to those from native and feral animals. Cryptosporidium and Giardia were
found in at least one sample from each of the domestic animal species.
The highest median concentration of E. coli was found in poultry faeces. Clostridium perfringens
spores were highest in domestic cat faeces. Cryptosporidium oocysts were highest in the faeces of
domestic pigs and Giardia cysts in dog faeces.
Across the catchments, water and sediment samples from the Shoalhaven appeared to contain
lower pathogen concentrations than those from the Coxs, Wollondilly and Wingecarribee
catchments, with some samples testing free of pathogens altogether. The Shoalhaven catchment
also had the lowest electrical conductivity and turbidity levels.
The upstream site on the Coxs River contained the poorest water quality in terms of pathogens.
Analysis of the data obtained from sampling the final effluent from 11 sewage treatment plants
(STPs) on three occasions found Cryptosporidium oocysts and Giardia cysts on at least one
sampling occasion from each STP. Goulburn and Wallerawang STPs typically had the poorest
quality effluent.
Overall, the results give a snapshot of pathogen levels across the catchments during dry weather.
They suggest that introduced, domestic or feral animals, and treated sewage effluent, rather than
native animals, are the major sources of pathogenic organisms in SCA catchments, with the types
of pathogen being broadly related to the source type. The next phase of the Hotspots program will
address variations in pathogens over time.
page 27
7.6 Summary of water quality incidents
The Memorandum of Understanding between the SCA and the NSW Department of Health
mandates response plans for incidents that may pose a risk to water quality. The SCA Corporate
Incident Management Manual sets out the appropriate response to incidents which are classified
according to risk from minor to emergency.
Incidents can relate to water quality, water supply or a number of other contingencies. The SCA
has developed response plans for high-risk (but low probability) contingencies such as water
contamination or the failure of delivery infrastructure. For water quality incidents, the SCA may
order additional water quality monitoring as part of its response.
7.6.1
Between July 2001 and June 2002 the SCA logged a total of 27 incidents in relation to water
quality, (Table 5) one of which was classed as an emergency, three as major events, and the
remaining 23 as minor.
The most serious incident occurred in March 2002 when monitoring detected a high count of
thermotolerant coliforms in a picnic tap at Bendeela Picnic Area (HBP2). Resampling found the
threat had diminished. Of the three major incidents, monitoring detected a high count of
thermotolerant coliforms at a picnic area tap at Cataract. Immediate action was taken to flush the
system and re-chlorinate the supply.
The presence of high levels of thermotoernt coliforms in the drinking water does not pose a health
risk in itself, however their presence is an indicator that other pathogens, which are less easily
identifiable, may also be present in the water supply.
NSW Health and the World Health Organisation have indicated that new guidelines should apply
to the monitoring of water quality at picnic area taps. This changes the focus of monitoring to the
monitoring of e-coli at the service reservoir, in preference to residual chlorine and coliform levels
at the tap. Responding to the perceived risk, the SCA has developed drinking water safety plans in
conjunction with NSW Health for its picnic area supplies. It is important to note that under the
proposed new guidelines, these would still have been classified as major incidents.
An incident at Woronora WFP saw diluted backwash water discharged into Woronora Dam for a
short period. Monitoring did not reveal any significant impact on raw water quality in the
reservoir.
Cyanobacterial levels in Lake Yarrunga (DBRE) near the Bendeela Boat Ramp triggered a third
incident but re-sampling showed no problems.
page 28
The minor environmental incidents included two bushfire related events and four minor
contamination events.
Part 2 - Table 5
Class
number
examples
minor incident
23
unusual water quality characteristics such as high turbidity or pathogens in raw
water samples; dead animal in canal
major incident
3
thermotolerant coliforms detected in picnic area taps; WFP failure;
cyanobacteria detected
emergency
1
high levels of thermotolerant coliforms in picnic area taps and low residual
chlorine
total
27
7.7 Wet weather events
The 2001–2002 monitoring year was dry until after the severe bushfires of December and January.
Runoff from a number of rainfall events – two in February, one in late March and a small event in
mid-April – was monitored to determine any impacts on catchment water quality (discussed
above).
Artificial aerators in Woronora, Nepean and Avon reservoirs help to prevent thermal stratification
of the stored water over the warm summer months. Aerators were switched off in February after
heavy rain in the catchments.
Overall, wet weather samples had poorer water quality than dry weather samples, as indicated by
their higher median concentrations of most analytes. Low levels of pathogens were noted in the
inflows to Lake Burragorang and Woronora Reservoir in wet weather samples taken after the
December–January bushfires (see Bushfires 7.1).
page 29
8 Protecting public health
8.1 The SCA – protecting public health
The SCA is committed to delivering safe, healthy bulk water supplies that meet all of the required
quality standards set out in the Operating Licence and Bulk Water Supply Agreement. Poor quality
water can make the treatment process less effective, more expensive or both.
8.1.1
Reducing risk
The SCA manages threats to water quality throughout its area of operation - including
inappropriate land use, disposal of treated sewage effluent, chemical leaks and spills, and other
events - through a comprehensive suite of plans and programs.
The water quality monitoring program provides an early warning of potential problems in
catchment streams, reservoirs, delivery systems and picnic area taps. The SCA monitors specific
threats to human health such as pathogens, cyanobacteria and pesticides.
The Bulk Raw Water Quality Management Plan is a comprehensive, multi-faceted approach to
protecting the quality of water entering, stored in and supplied from SCA dams. The plan
addresses the challenges of maintaining and improving water quality by integrating a whole-ofcatchment management approach with appropriate water delivery solutions.
The SCA has developed a Corporate Risk Management Plan to identify events and activities that
could affect the SCA’s abilities to achieve its objectives. Risk treatment actions have been
developed for those risks assessed as ‘medium’ and have been incorporated into divisional work
plans.
A five-year Pollution Source Risk Management Plan (PSRMP) has been developed to identify and
mitigate pollution sources in the water supply catchment. Actions under this plan include the
systematic identification of hazards to water quality and catchment health in the SCA’s area of
operation as part of the Environmental Assessment of Sites and Infrastructure (EASI) projects.
The Corporate Incident Management Manual and Bulk Water Quality Incident Response Plan set
out in detail a framework of procedures for the identification, response and management of water
quality events. They define what the SCA must do, in response to an event, to ensure that public
health is not threatened.
The Blue Gren Algae Contingency Plan sets out procedures to be followed to ensure the effective
management of blue green algal blooms across the SCA area of operations.
page 30
8.1.2
Other actions
The SCA is minimising any threat to human health from its activities by:
artificially destratifying reservoirs to help prevent the conditions needed for blooms of algae
and cyanobacteria
conducting ‘hotspots’ research to identify the sources and distribution of pathogens in
catchments
assessing agricultural and industrial contaminants in inflows to reservoirs, and
targeting more efficient methods for detecting trace levels of difficult-to-treat chemicals in
water supplies.
8.1.3
SCA business plan
The SCA has produced a business plan that, among other things, sets clear objectives for
minimising the risk to water quality. Over the next five years it aims to:
reduce discharges of treated sewage effluent to catchment waters
improve the quality of stormwater and other urban run-off
reduce the sediment load on catchment waters
reduce the risk of poor water quality resulting from bushfires
ensure that new developments have a neutral or beneficial impact on water quality, and
improve catchment health through sustainable land use and catchment management.
The business plan sets clear targets for achieving the above objectives which will result in water
quality continuing to meet or exceed agreed criteria at least 95 per cent of the time.
page 31
9 References
Supply Agreement.
SCA, 2000. Pollution Source Risk Management Plan
SCA, 2001. Bulk Raw Water Quality Management Plan
SCA, 2001. Corporate Risk Management Plan
SCA, 2000. Blue Green Algae Contingency Plan
SCA, 2002. Bulk Water Quality Incident Response Plan
SCA, 2001. Corporate Incident Management Manual
SCA, 2000. Bulk Water Quality Incident Response Plan. Sydney Catchment Authority,
Sydney.
SWC, 1999. Annual Environment and Public Health Report, 99. December 1999. Sydney
Water Corporation.
page 32
Part 3: Monitoring for the Water Management Licence
Acknowledgements:
page 2
Contents
1
4
2
About this report
4
3
Monitoring for the Water Management Licence
5
4
3.1
Summary
5
3.2
Temperature monitoring downstream of dams
5
References
7
page 3
managing the catchments that provide Sydney’s bulk water supply. It was established in 1999
following an independent NSW government inquiry into Sydney’s water supply.
The SCA’s task is to supply quality bulk raw water to its customers, which include Sydney Water,
NSW's population.
2 About this report
This report is Part 3 of the SCA’s Annual Water Quality Monitoring Report. It presents the results
of water quality monitoring undertaken to meet the requirements of the Water Management
Licence with the Water Administration Ministerial Corporation, administered by the Department
of Land and Water Conservation (DLWC). This report is a companion to the Annual Compliance
Report produced under the requirements of the Licence.
2001 to June 2002.
purposes.
page 4
3 Monitoring for the Water Management Licence
3.1 Summary
Daily monitoring of river water temperatures in the Hawkesbury-Nepean, Woronora and
Shoalhaven rivers showed negligible impact from water released by upstream dams at nearly all
locations. Immediately downstream of Tallowa Dam however river water temperatures were
reduced by up to 4°C from November 2001 to January 2002.
3.2 Temperature monitoring downstream of dams
The SCA’s Water Management Licence (DLWC 2001) requires environmental flows to be
released from storages to help maintain the ecological health of downstream rivers. Water released
from storages into rivers can be colder or warmer than the receiving water depending on the
position of the water offtake in the storage (deeper water usually being colder than surface water),
with offtake levels usually set to meet drinking water quality requirements. To investigate the
effect of water releases on downstream sites, water temperature was monitored daily in the
Hawkesbury-Nepean (nine sites), Woronora (one site) and Shoalhaven (two sites) rivers. The
monthly median temperatures are presented in Part 3 - Figure 1.
3.2.1
Hawkesbury-Nepean River
The water temperature at sites downstream of water releases was often cooler than that of the
receiving bodies, but the change in river water temperature was minimal. This was probably
because release volumes were relatively small.
For releases from Warragamba Dam to the Hawkesbury-Nepean River, Penrith is the downstream
site and Wallacia is the control site. There was no significant difference in temperature between
these sites, both of which followed a seasonal pattern throughout the year.
3.2.2
Shoalhaven River
Downstream of Tallowa Dam (E851), water temperatures from November 2001 to January 2002
were below the expected seasonal trend by up to 4°C. Water released from the dam has reduced
page 5
immediate downstream water temperatures significantly during this period. During the year, a
study of water quality in Lake Yarrunga also identified that temperature of releases had an effect
on the downstream environment. Options to mitigate these effects are being investigated.
3.2.3
Woronora River
The water temperatures downstream of the Woronora Dam at the Needles (G0515) were
monitored for the purpose of establishing baseline data of the seasonal pattern throughout the year
for comparison with, once environmental releases are commenced early in 2003. Measured
temperatures were similar to those of the Hawkesbury-Nepean River.
Overall, the downstream effect of release waters on ambient river temperatures and ecosystems
was negligible, with the exception of the Shoalhaven River immediately downstream of Tallowa
Dam.
Part 3 - Figure 1: Effect of dam releases on downstream river temperatures
page 6
4 References
Supply Agreement.
SCA, 2000. Operating Licence.
WAMC, 2001. Water Management Licence Issued to Sydney Catchment Authority, Water
Administration Ministerial Corporation, New South Wales.
page 7
PART 4: MONITORING FOR OPERATIONS AND PLANNING
1
The Sydney Catchment Authority (SCA) is
a NSW state government agency responsible
for managing the catchments, dams and
infrastructure that provide Sydney’s bulk water
supply. It was established in 1999 following an
independent NSW government inquiry into
Sydney’s water supply.
Drinking water for Sydney and surrounding areas is
collected from five primary catchments, occupying
16 000 square kilometres. It is stored in a total of 21
dams, holding over 2.5 million megalitres of water.
The SCA’s main task is to supply quality bulk raw
water to its customers, which include Sydney Water and
a number of local councils in the Southern Highlands,
Illawarra and the Shoalhaven. These customers then
filter and distribute the water to nearly four million
people – about 60 per cent of NSW’s population.
SYDNEY’S DRINKING WATER CATCHMENTS
SYDNEY CATCHMENT AUTHORITY WATER QUALITY MONITORING REPORT 2001–2002
1
2
3
About this report
This report is Part 4 of the Sydney Catchment
Authority’s water quality monitoring report,
2001–2002. This part presents detailed technical
results for the monitoring program undertaken for
operational and planning purposes. The monitoring
data has been compared with guidelines from the
Bulk Water Supply Agreement (BWSA) (Table 4.1)
as an indication of water quality, however there are
no compliance requirements for operating and
planning data.
Catchment monitoring
In other parts of the water quality monitoring report:
Part 1: Introduces the SCA and its activities, provides an
overview of how the SCA collects, stores and distributes
water, and explains why the SCA needs to monitor water
quality. This part then broadly sums up all of the SCA’s
water quality monitoring activities and results from July
2001 to June 2002.
Part 2: Details how the delivery system has performed in
relation to the SCA Operating Licence and Bulk Water
Supply Agreement between SCA and Sydney Water.
Part 3: Details the results of river temperature monitoring
below major reservoirs, undertaken to fulfil the needs of
the Water Management Licence.
The full report can be viewed on the SCA’s website
www.sca.nsw.gov.au.
TABLE 4.1: WATER QUALITY GUIDELINES FOR CATCHMENTS
AND RESERVOIRS
Analytes (Unit)
Catchments
Reservoirs
Dissolved Oxygen
(% saturation)
90–110
90–110
pH (pH unit)
6.5-8.0
6.9-8.1* (LB)
6.0–7.2** (O)
Turbidity (NTU)
25
20
Total Iron (mg/L)
na
0.3
na
0.1
na
0.050
0.010
0.50
0.35
Thermotolerant Coliforms
(CFU/100 mL)
150
100
Chlorophyll–a (µg/L)
7
Cyanobacteria Abundance
(cells/mL)
na
15000
Toxigenic Cyanobacteria
(cells/mL)
na
2000
(mm2/L)
na
2
References:
SCA (1999);
ANZECC (2000);
HRC (1998);
NHMRC (1996);
SACC (2001);
SCA (2000);
SWC (1999)
2
0.2
5
Notes:
* LB = Lake Burragorang and Prospect Reservoir;
** O = other lakes.
na = not applicable
3.1 MANAGING SYDNEY’S WATER SUPPLY
CATCHMENTS
3.2 RESULTS
The SCA’s bulk water supply is drawn from the
catchments of five major river systems in:
• Warragamba
• Upper Nepean
• Woronora
• Shoalhaven, and
• the Blue Mountains.
3.2.1 Warragamba Catchment
These catchments span 18 local government areas
covering an area of almost 16 000 square kilometres.
Part 1 of this report provides a detailed description of
each catchment area, reservoir, delivery system and
sampling site.
Coxs River (E083) showed good water quality with only
one sample recording dissolved oxygen outside the
guideline range in dry weather. Wet weather sampling
indicated pH values exceeding the guideline on one of
two occasions and total nitrogen exceeded the guideline
value on 60 per cent of occasions (6 samples). The
frequency of readings outside guideline ranges decreased
relative to the 2000–2001 data for pH, dissolved oxygen,
turbidity, thermotolerant coliforms and total nitrogen.
As in 2000–2001, the quality of inflows close
to Lake Burragorang was generally good, meeting
guideline concentrations on most sampling occasions.
Outer catchment sites more frequently failed to meet
the guidelines, particularly with respect to pH and
dissolved oxygen.
The lower Nattai River (E210) showed generally good
water quality in dry weather with all monitoring data
within guidelines except for turbidity, thermotolerant
coliforms and total phosphorus on one occasion and
total nitrogen on two occasions. The lower dry weather
coliform concentrations observed in 2000–2001
continued in 2001–2002 and can be attributed to the
recent upgrading of the Mittagong Sewage Treatment
Plant (STP). Wet weather samples were outside guideline
ranges with greater frequency than in 2000–2001 for
dissolved oxygen, turbidity, thermotolerant coliforms,
total nitrogen and total phosphorus. Chlorophyll–a was
not detected above the guideline in 2001–2002.
The upper Nattai River (E206) water quality was
outside guideline ranges on fewer occasions than in
2000–2001, although total nitrogen and total
phosphorus were regularly above guideline levels and
dissolved oxygen was below the guideline range on
50 per cent of occasions. Wet weather water quality was
also outside guideline ranges for turbidity, thermotolerant
coliforms, total phosphorus and chlorophyll–a on fewer
occasions than in 2000–2001. Dissolved oxygen and total
nitrogen were outside guideline ranges at a similar
frequency to that observed in 2000–2001 (50 per cent
and 100 per cent respectively).
3
Catchment monitoring cont’
The lower Wollondilly River (E488) showed improved total
nitrogen concentration with no guideline exceedances in
dry weather. However, dissolved oxygen measurements
were outside the guideline ranges more frequently in dry
weather than in 2000–2001. Wet weather samples showed
a significant reduction in the frequency of guideline
exceedance for thermotolerant coliforms and an increase in
frequency for total nitrogen, total phosphorus and
chlorophyll–a. The central Wollondilly River (E450)
showed similar dry weather water quality to that in
2000–2001, except that thermotolerant coliforms were
always within the guidelines in 2001–2002.
In the upper Wollondilly River (E409) and Mulwaree River
(E457), dry weather water quality deteriorated relative to
2000–2001, with pH, dissolved oxygen, total phosphorus,
total nitrogen and chlorophyll–a regularly outside the
guideline ranges. However, wet weather water quality
improved with respect to turbidity and chlorophyll–a while
the frequency of guideline exceedance for thermotolerant
coliforms, total nitrogen and total phosphorus was similar
to that observed in 2000–2001 (50 per cent, 100 per cent
and 100 per cent respectively). No wet weather data for pH
or dissolved oxygen was available in 2001–2002.
Similar conditions were observed in the Wingecarribee
River (E332) although turbidity and chlorophyll–a
exceeded guideline concentrations at a greater frequency
than in the Wollondilly River. This suggests that elevated
nutrient levels in the Wingecarribee, Mulwaree and upper
Wollondilly rivers are encouraging algal growth, with
consequent consumption of dissolved oxygen and elevation
of pH. The upper Wollondilly River is affected by a number
of treated wastewater discharges in and around Goulburn
that may be a source of elevated nutrients. The upper
Wingecarribee River experiences elevated nutrient levels
from fertilisers used in the catchment, although monitoring
in Wingecarribee Swamp suggests the swamp is filtering
Dry weather water quality declined slightly in Little River
(E243) from 2000–2001 with pH, dissolved oxygen and
total nitrogen falling outside guideline ranges occasionally.
Wet weather sampling declined also, with turbidity, total
nitrogen and total phosphorus exceeding guidelines more
often than in 2000–2001.
Dissolved oxygen was outside the guidelines in the
Kowmung River (E130) in dry weather more often than last
year, while thermotolerant coliforms exceeded guideline
levels on one occasion only in dry weather. Wet weather
data for this location showed an increased incidence of
thermotolerant coliforms and total nitrogen exceeding
guideline concentrations.
Sampling in the Kedumba River (E157) showed fewer
exceedances of total nitrogen but a slight increase in
turbidity, dissolved oxygen and total phosphorus
exceedances. Wet weather sampling showed fewer
exceedances of dissolved oxygen and thermotolerant
coliform guidelines, but more exceedances of pH, turbidity,
total nitrogen and total phosphorus than in 2000–2001.
Werriberri Creek (E531) showed a reduced frequency of
dissolved oxygen and chlorophyll–a concentrations outside
the guideline ranges in dry weather, with dissolved oxygen
below the guideline range on 91 per cent of occasions and
chlorophyll–a not present above guideline levels. Dissolved
oxygen was depleted at this location on all occasions in
2000–2001. A slight increase in exceedance frequency was
observed for thermotolerant coliforms, total nitrogen and
total phosphorus. Wet weather monitoring indicated a
decline in water quality with a slight increase in exceedance
frequency for dissolved oxygen depletion, thermotolerant
coliforms, total nitrogen and chlorophyll–a.
3.2.2 Nepean Catchment
3.2.4 Lake Yarrunga (Shoalhaven) Catchment
The Nepean (E601) and Burke (E602) rivers are the two
major inflows into Lake Nepean. The dry weather water
quality of the Nepean River remained good, with no
guideline exceedances except for total nitrogen in five out
of eight sampling events. This frequency of exceedance is
higher than in 2000–2001. Wet weather water quality
improved in comparison to the 2000–2001 data, with
fewer guideline exceedances for turbidity (eight per cent),
thermotolerant coliforms (33 per cent), total nitrogen (71
per cent) and total phosphorus (nine per cent).
Dry weather water quality within the Shoalhaven catchment
was generally within guideline concentrations, except for
dissolved oxygen, which was below guideline
concentrations on numerous occasions in all monitoring
locations, and total nitrogen in Boro Creek (E890), which
exceeded guideline concentrations on 18 per cent of
occasions. Guidelines were exceeded more frequently than
in 2000–2001.
Dry weather water quality in the Burke River was also
generally good, with only a slightly increased proportion of
samples having pH and dissolved oxygen measurements
outside the guideline values. Wet weather water quality was
generally good, except for occasional non-compliances for
dissolved oxygen, turbidity, thermotolerant coliforms, total
nitrogen and total phosphorus. Guideline exceedance
frequency was generally similar to that of 2000–2001.
These exceedances are most likely related to agricultural
land use within the catchment.
3.2.3 Avon, Cataract, Cordeaux, Woronora and Blue
Mountains Catchments
These catchments are predominantly bushland and so
require no water quality monitoring sites. Water quality is
monitored in the reservoirs and delivery systems only.
Water quality in the catchment deteriorated during wet
weather. Chlorophyll–a regularly remained within guideline
levels except in the Kangaroo River (E706), Central
Shoalhaven River (E861) and Gillamatong Creek (E891).
Dissolved oxygen was frequently below guideline
concentrations at all sites except Boro Creek (E890).
Turbidity was frequently poor in wet weather throughout
the catchment, with the exceptions of Gillamatong Creek
(E891), Mongarlowe River (E822) and in the Shoalhaven
River downstream of its confluence with the Marlowe
River (E861). Concentrations of thermotolerant coliforms
and nutrients (total nitrogen or total phosphorus)
frequently exceeded guideline levels in wet weather at all
locations. Nutrients and chlorophyll–a across the catchment
exceeded guidelines more frequently than in 2000–2001.
Dissolved oxygen and thermotolerant coliform
concentrations exceeded guidelines more frequently or
remained similar to those in 2000–2001.
The observed impacts on water quality can be attributed to
the land uses within the catchment (detailed in Part 1).
The Oaks township is unsewered and is a possible source of
thermotolerant coliform and nutrient contamination in
Werriberri Creek. The elevated nutrient levels would
provide good conditions for algal growth and may
contribute to the elevated chlorophyll–a concentrations and
depleted dissolved oxygen observed in the creek. A
reticulated sewerage system, which would reduce these
impacts, is currently under construction.
DAPI-positive Giardia cysts were detected in dry weather in
Kowmung and Kedumba rivers and in Gibbergunyah Creek
but not in Lake Burragorang. They were not detected
during wet weather. Those from Gibbergunyah Creek are
probably from the Mittagong STP which lies upstream of
the sampling point, which would explain the relatively high
numbers of cysts detected (up to 576 cysts/100 litre). Low
levels of DAPI-positive Cryptosporidium oocysts were
detected in Werriberri Creek (E531) in both wet and dry
weather (possibly from The Oaks township), and on two
occasions in Lake Burragorang.
4
5
4
Lake monitoring
3.3 PERFORMANCE ASSESSMENT –
ALL CATCHMENTS
4.1 RESULTS AND DISCUSSION
Water quality in the catchments was compared to guidelines
specified by ANZECC (2000) for dissolved oxygen, pH,
turbidity and thermotolerant coliforms, and by the Healthy
Rivers Commission (1998) for total phosphorus, total
nitrogen and chlorophyll–a.
4.1.1 Lake Burragorang
Water quality in the Warragamba catchment was generally
good, complying with water quality guidelines on most
sampling occasions at the inflows to Lake Burragorang.
Water quality in the outer catchment sites was not as good,
with more frequent exceedances of guidelines for pH,
dissolved oxygen, nutrients and chlorophyll–a. Water
quality generally deteriorated in wet weather.
Water quality in the Nepean catchment was good, with dry
weather guideline exceedances limited to total nitrogen in
the Nepean River, and pH and dissolved oxygen in the
Burke River. Wet weather sampling showed poorer water
quality in both rivers, particularly for turbidity,
thermotolerant coliforms and nutrients.
Water quality in the Shoalhaven catchment was generally
very good, except for frequently depleted levels of dissolved
oxygen throughout the catchment during dry weather.
Total nitrogen exceeded guideline concentrations at Boro
Creek on several occasions. Wet weather samples showed
poorer water quality than in dry weather, with higher levels
of turbidity, thermotolerant coliforms and nutrient
concentrations. Chlorophyll–a exceeded the guidelines
during wet weather in the Kangaroo and central
Shoalhaven rivers and in Gillamatong Creek.
Water quality in Lake Burragorang was generally good
throughout the year, with thermotolerant coliforms
below guideline levels at all times. Turbidity was at or
below guideline levels for 99 per cent of the time. Some
other characteristics exceeded guidelines, however, as
outlined below.
Cyanobacteria were frequently present in excess of
guideline concentrations at all locations within
Lake Burragorang (42–92 per cent of occasions).
Toxigenic cyanobacteria were detected at some of the
sampling sites within Lake Burragorang but were rarely
above guideline concentrations.
Dissolved oxygen concentrations were outside guidelines
in 26 per cent (DWA9, Warragamba Dam) to 84 per cent
(DWA27, Wollondilly Arm, 23 kilometres upstream of
Warragamba Dam at Bimlow) of samples, largely from
supersaturation of the water. Supersaturation may
indicate excessive plant or algal growth but is unlikely to
directly threaten aquatic biota. Supersaturation may also
result from wind action and was observed on numerous
occasions in reservoirs in 2000–2001.
Dissolved oxygen was depleted at some sites, but was not
recorded below 68 per cent at any site. While depleted
dissolved oxygen can threaten biota in reservoirs, any
risk can be reduced with artificial destratification systems
such as those in place in a number of SCA reservoirs.
The chlorophyll–a guideline level of 5 micrograms
per litre (µg/L) was regularly exceeded by a small amount
at some sites, with a recorded maximum at any site of
19 µg/L. For instance, 67 per cent of observations in the
Coxs River arm 36 kilometres upstream of the dam
wall (DWA19), 32 per cent in the Coxs River arm
37 kilometres upstream of the dam wall (DWA21)
and 30 per cent in the Wollondilly River arm at
Tonalli (DWA39), were above the guideline level.
High chlorophyll–a concentrations occurred many
kilometres upstream and posed little threat to water
quality at the dam.
Sites complied with total phosphorus guidelines at least
93 per cent of the time except for the sites DWA19,
DWA21 and DWA39, which had 33 per cent, 40 per cent
and 70 per cent compliance respectively. These are the
same sites with elevated chlorophyll–a concentrations
and were all many kilometres from the dam wall.
Total nitrogen guidelines were infrequently exceeded
(on up to 7 per cent of occasions) in locations away from
the dam wall.
The exceedance rates for pH were generally greater
than in 2000–2001, although the maximum and
minimum pH values observed were within 1 pH unit
of the guideline range in all cases. Overall, pH tended
to be alkaline rather than acidic. The observed pH,
nutrient, cyanobacteria and chlorophyll–a concentrations
indicate the potential for problem algal growth in
Lake Burragorang.
Cryptosporidium oocysts were detected at low levels
(7 oocycts/100 litres) at a site within Lake Burragorang
(DWA2) on three occasions during November and
December 2001, two of which returned positive
DAPI tests. The single Giardia cyst detected was not
DAPI–positive.
In summary, all characteristics were generally
consistent with 2000–2001 results except for pH
and cyanobacteria, which were outside guideline
concentrations more frequently than in 2000–2001,
and minor instances of Cryptosporidium oocysts which
were not detected at all in 2000–2001.
6
7
Lake monitoring cont’
4.1.2 Prospect Reservoir
4.1.3 Nepean Reservoir
4.1.4 Avon Reservoir
4.1.5 Cataract and Cordeaux reservoirs
At the two sites in Prospect Reservoir (RPR1, RPR3), water
quality was generally good. Water quality close to the
pumping station at the end of the south-western arm
(RPR3) was within guideline concentrations except when
turbidity exceeded its guideline on one occasion and
cyanobacteria on 83 per cent of occasions. Toxigenic
cyanobacteria were detected, but never above guideline
concentrations.
Water quality in the Nepean Reservoir was generally good,
with exceedance frequencies for total nitrogen,
chlorophyll–a and cyanobacteria decreasing relative to
2000–2001. However, dissolved oxygen and pH were
frequently outside the guideline ranges. Thermotolerant
coliforms were detected above guideline concentrations on
one occasion. Total iron and total manganese exceeded the
guideline concentrations on a number of occasions,
continuing a pattern observed in 2000–2001. Exceedance
frequencies for these metals in 2001–2002 were however
slightly higher.
The relatively small Avon Reservoir catchment comprises
highly protected land and mainly bushland. Consequently,
there are no catchment monitoring sites for this reservoir.
Water quality sampling is conducted at the junction of two
channels which flow into the main lake at Upper Avon
(DAV7). It is from this point that water is abstracted to
supply the Illawarra region.
Cataract (DCA1) and Cordeaux (DCO1) reservoirs are
similar both in size and water quality characteristics. Both
storages discharge to the Upper Canal Delivery System.
Cataract Reservoir discharges to the Cataract River, about
10 kilometres upstream of Broughtons Pass. Cordeaux
Reservoir discharges to the Cordeaux River, 20 kilometres
upstream of Pheasants Nest Weir which diverts water
through a tunnel to Broughtons Pass Weir.
At the mid-lake site (RPR1), pH and cyanobacteria were
frequently outside guideline ranges, although toxigenic
cyanobacteria when detected were below guideline
concentrations and pH was within 1 pH unit of the
guidelines at all times. Dissolved oxygen was occasionally
outside the guideline ranges, and total nitrogen exceeded
the guidelines on one occasion.
Cyanobacteria counts exceeded guideline concentrations
at both sites more frequently than in 2000–2001,
as did the pH at RPR1 and turbidity at RPR3.
However, no instances of elevated chlorophyll–a at RPR1
or total nitrogen at RPR3 were seen this year, unlike
2000–2001. Other characteristics remained consistent with
2000–2001 measurements.
Water quality in this reservoir is known to be susceptible to
wet weather impacts due its proportionally larger
catchment area. The observed increases in turbidity and
total metals are typical of these impacts.
The depleted dissolved oxygen concentrations observed
at this location are related to thermal stratification of
the reservoir (see Part 1), which can also result in elevated
metal concentrations. A lake aerator has been used
during the warmer months since 1995 to help combat
this problem.
Total cyanobacteria counts exceeded the guidelines
occasionally; however, no toxigenic cyanobacteria
were detected.
8
The most frequent exceedances of guideline values were
dissolved oxygen (48 per cent) and cyanobacteria (40 per
cent). No toxigenic cyanobacteria were detected.
Chlorophyll–a exceeded guideline concentrations on only
12 per cent of occasions, less frequently than in
2000–2001.
Nutrients (total nitrogen) and particulate metals were
occasionally above guideline concentrations. The
monitoring site is known to be susceptible to increases in
turbidity and particulate metal concentrations after wet
weather. These effects have been observed to persist for
only a few days after a wet weather event.
The pH was occasionally elevated and dissolved oxygen
was outside guideline ranges on 58 per cent of occasions,
probably resulting from excessive algal growth.
Total cyanobacteria counts exceeded the guidelines,
however toxigenic cyanobacteria were detected only twice,
and were well below the guidelines on both occasions.
Water quality in the upper 12 metres of these reservoirs was
monitored regularly, and was found to be generally within
the guideline levels for most characteristics.
Cyanobacteria and chlorophyll–a concentrations exceeded
guidelines on three occasions in Cataract Reservoir and
four in Cordeaux Reservoir during the warmer months
(November 2001 to April 2002). These occurrences were
more frequent than in 2000–2001. No toxigenic species
were detected. Nutrient concentrations in Cordeaux
Reservoir exceeded guidelines more frequently than in
2000–2001, which may have provided more favourable
conditions for the growth of algae, leading to the observed
chlorophyll–a and cyanobacteria counts.
Thermal stratification resulted in oxygen depletion in the
bottom layers of the lakes with subsequent diffusion of iron
and manganese from the sediments into the deep lake
water. As the reservoirs are not artificially destratified,
natural mixing in autumn results in peak metal
concentrations and depleted oxygen near the surface. A
similar pattern was observed in 2000–2001.
9
4.1.6 Woronora Reservoir
4.1.7 Blue Mountains reservoirs
4.1.8 Lake Yarrunga
4.1.9 Fitzroy Falls Reservoir
The water of Woronora Reservoir is relatively low in
alkalinity, and is slightly more acidic than the waters of the
other reservoirs, a characteristic of its catchment. Water
quality was good, and generally similar to that observed in
2000–2001. Chlorophyll–a and cyanobacteria were within
guideline concentrations at all times. No toxigenic
cyanobacteria were detected.
Monitoring was conducted in the Upper Cascade (DTC1),
Lower Cascade (DLC1) and Greaves Creek (DGC1)
reservoirs. The monitoring points are close to the water
supply offtakes.
Lake Yarrunga on the Shoalhaven River had poorer water
quality than the other reservoirs managed by SCA. The lake
stratifies in summer resulting in depleted dissolved oxygen
and elevated nutrients and metals in the bottom layer,
particularly in the deeper locations of the Dam Wall
(DTA1) and Yarrunga Junction (DTA3). Seasonal mixing of
the lake brings this poorer quality water to the surface. The
maximum total iron concentration of 12.91 milligrams per
litre was observed at DTA3 in May 2002, consistent with
natural autumnal destratification.
The Fitzroy Falls Reservoir is relatively shallow (average
depth 4.5 metres) and is therefore less prone to thermal
stratification. Consequently, metals concentrations were
below guideline levels on all occasions.
Turbidity and pH were also good, with only 2 per cent and
1 per cent of measurements respectively being outside
guideline values.
Dissolved oxygen was similar to that observed in
2000–2001, with 33 per cent of observations outside the
guideline range. Depleted dissolved oxygen levels occurred
in cooler months and may be related to destratification of
the reservoir. Supersaturation in summer months could be
related to aquatic plant growth (which was within guideline
levels), to wind action, or both.
Total iron and total manganese exceeded the guideline
concentrations on one occasion in autumn, probably
because of natural seasonal mixing of the reservoir.
Water quality in the Blue Mountains reservoirs was good in
2001–2002. At Lower Cascade (DLC1) pH exceeded the
guideline on 83 per cent of occasions but by no more than
a small margin (a maximum of 0.8 pH units). Dissolved
oxygen fell below the guidelines on only two occasions (14
per cent of samples).
Chlorophyll–a exceeded guideline concentrations in Upper
Cascade (DTC1) less often than in 2000–2001, possibly
because of water being diverted from the Fish River
Scheme. The maximum cyanobacteria concentration
decreased from 11 000 cells per millilitre (cells/mL) in
2000–2001 to 5277 cells/mL in 2001–2002, and on no
occasion exceeded the guideline level. Toxigenic cells were
detected only three times throughout the year, and only at
very low levels (53 cells/mL maximum). Total phosphorus
exceeded the guideline level less often than in 2000–2001,
but total nitrogen exceeded the guidelines more often.
At Greaves Creek (DGC1), water quality was also good,
except for consistently elevated concentrations of total iron,
which exceeded guideline concentrations on all occasions as
in 2000–2001. Chlorophyll–a exceeded the guidelines more
frequently than in 2000–2001. Dissolved oxygen was below
the guideline range on 40 per cent of occasions, which is
less frequently than in 2000–2001. Total cyanobacteria
numbers exceeded the guidelines only once throughout the
year and on the one occasion that toxigenic cells were
detected, they were at a very low level (12 cells/mL).
Total phosphorus (82 times or 100 per cent of occasions)
and total nitrogen (61 times or 91 per cent of occasions)
almost always exceeded the guidelines. Elevated nutrient
concentrations are consistent with regular chlorophyll–a
and cyanobacteria counts above guideline concentrations at
all sites. Levels of toxigenic cyanobacteria detected at DTA1
and DTA8 had microcystin-LR toxicity equivalents of 0.3
and 0.4 µg/L respectively and were well below the guideline
value (1.3 µg/L).
Across all sites, thermotolerant coliforms were detected
above guideline concentrations in 10–33 per cent of
observations.
Although pH exceeded guidelines regularly at all locations,
the values were all within 0.5 pH units of the guideline for
reservoirs (pH 7.2), with the maximum pH of all sites (pH
7.7) observed at DTA3. The neutral to mildly alkaline
nature of these waters is not a problem, and the results are
consistent with those obtained in 2000–2001.
However, the nutrient loading was high with nearly all
observations for total nitrogen and total phosphorus
exceeding the guideline values. Algal growth was abundant
under these conditions with chlorophyll–a exceeding
guidelines on 94 per cent of occasions and cyanobacteria
levels exceeding guidelines on all occasions. Toxigenic
cyanobacteria were detected exceeding the guideline level
of 2000 cells/mL for 25 per cent of the time, but
microcystin-LR toxicity equivalents were 0.8 µg/L or less,
well below guideline levels. This pattern is similar to the
2000–2001 results except that nutrients and chlorophyll–a
exceeded guideline levels more frequently in 2001–2002.
Dissolved oxygen was depleted (below the guideline range)
on 50 per cent of occasions, more frequently than in
2000–2001, and pH was elevated slightly above guideline
concentrations on 96 per cent of occasions (similar to
2000–2001). These measurements are consistent with the
observed abundance of algal growth.
4.1.10 Wingecarribee Reservoir
Wingecarribee Reservoir (DWI1) is another shallow
reservoir, having a maximum depth of 12 metres. It is
not prone to thermal stratification, with the result that
metals concentrations remained below guidelines
throughout the year.
However, nutrient levels were high, with total nitrogen
exceeding the guideline concentrations on 90 per cent of
occasions and total phosphorus exceeding guidelines on all
occasions. Chlorophyll–a and cyanobacteria exceeded
guidelines on 82 per cent and 96 per cent of occasions
respectively. Low levels of toxigenic cyanobacteria
(microcystin-LR toxicity equivalents of 0.5 µg/L or less,
well below guideline levels) were detected from February
2002 to June 2002.
The peat mass of Wingecarribee Swamp and upstream
agricultural land use are known to contribute to elevated
total nitrogen, total phosphorus and chlorophyll–a in the
Wingecarribee River, and most likely explain the observed
water quality impacts.
Similar to the pattern observed at Fitzroy Falls Reservoir,
dissolved oxygen was depleted on 27 per cent of occasions,
more frequently than in 2000–2001, and pH was elevated
slightly above guideline concentration on all occasions
(similar to 2000–2001). These measurements are consistent
with the observed abundance of algal growth.
10
11
Water quality in Lake Burragorang was generally good
throughout the year. However, non-toxigenic cyanobacteria
were regularly detected above guideline concentrations at
all locations throughout the year. Dissolved oxygen
concentrations regularly exceeded the guideline at two
locations, DWA9 and DWA27, 14 and 23 kilometres
upstream of the dam wall. Chlorophyll–a and total
phosphorus regularly exceeded guidelines in areas well
upstream of the dam wall. They are not considered to have
affected the quality of the water supply. The pH was within
1 pH unit of the guideline range in all samples, but tended
to be too alkaline.
Prospect Reservoir showed generally good water quality
throughout the year despite minor exceedances of turbidity,
pH, dissolved oxygen and cyanobacteria concentrations.
The indicator map of the Warragamba system (see Part 1)
illustrates the general performance of aesthetics,
eutrophication, recreation (catchment sites) and
bacteriological health (reservoirs), as outlined above.
Of note are the eutrophication indicators in the upper
Wollondilly and Wingecarribee rivers and the outer parts
of Lake Burragorang.
The Nepean Reservoir showed generally good water
quality, with improved frequency of compliance for
nutrients, chlorophyll–a and cyanobacteria, although
dissolved oxygen and pH were regularly outside guideline
ranges. A lake aerator treats thermal stratification at the
site; nonetheless, elevated metal concentrations were
detected at a greater frequency than in 2000–2001.
Avon Reservoir too showed generally good water
quality, but concentrations of dissolved oxygen and
cyanobacteria outside guideline values were common.
Toxigenic cyanobacteria were detected, but within guideline
levels. Nutrient, metals and pH occasionally exceeded
guideline concentrations.
5
Trend analysis in reservoirs
4.2 PERFORMANCE ASSESSMENT
Water quality in the Cataract and Cordeaux reservoirs was
generally within guidelines on all occasions. Nutrients,
chlorophyll–a and cyanobacteria were occasionally outside
guideline concentrations. A pattern of thermal stratification
was observed which affected dissolved oxygen and metal
concentrations in both reservoirs.
Woronora Reservoir had good water quality with only
minor exceedances of the turbidity and pH guidelines;
however, dissolved oxygen was regularly outside guideline
ranges.
The map of the Upper Nepean and Woronora systems (see
Part 1) indicates generally good water quality throughout
the catchment, but highlights the eutrophication found in
Avon and Cordeaux reservoirs.
Water quality in the Blue Mountains reservoirs was good.
However, pH regularly exceeded the guidelines at Lower
Cascade by a minor margin. Nutrients and chlorophyll–a
exceeded guideline levels in Upper Cascade, although less
frequently than in 2000–2001. The only exception to water
quality guidelines at Greaves Creek was persistently
elevated iron concentrations, also observed in 2000–2001.
The indicator map of the Blue Mountains System
(see Part 1) highlights eutrophication in the reservoirs.
Lake Yarrunga had the poorest water quality of all
reservoirs managed by the SCA. Thermal stratification in
the lake led to depleted dissolved oxygen levels and
elevated metal concentrations. Nutrients exceeded the
guideline concentrations on almost all occasions.
Chlorophyll–a and Cyanobacteria also frequently exceeded
guideline levels, although toxigenic cyanobacteria were
detected only once. Thermotolerant coliforms and pH were
also regularly above guideline concentrations.
Fitzroy Falls and Wingecarribee reservoirs had generally
good water quality, although nutrient concentrations were
almost always above guideline concentrations.
Chlorophyll–a and cyanobacteria concentrations were often
above guideline concentrations, probably as a result of
nutrient enrichment. Low levels of toxigenic cyanobacteria
were frequently detected but remained within guideline
concentrations. Dissolved oxygen and pH were also
regularly outside concentration ranges, probably because of
algal growth.
5.1 LONG–TERM TRENDS
5.1.2 Nutrients – total phosphorus and total nitrogen
Five key water quality variables measured at each
reservoir offtake site since 1990 were analysed for trends
using linear regression. These were:
• chlorophyll–a
• total phosphorus
• total nitrogen
• dissolved oxygen and
• pH.
Trends in nutrient concentrations in reservoirs are
affected by the water quality of inflows, which in turn is
determined by land use in the catchments. Rainfall
patterns (frequency and intensity) will also affect the
amount and timing of nutrient input into the reservoirs.
The results are summarised in Table 4.2. For those sites
where a significant trend was detected, the table lists the
typical annual change and standard error relative to this
change. Values are given in the units in which that
variable is reported throughout this report. Positive trend
values indicate rising levels, while negative trend values
indicate falling levels. Table 4.3 shows the actual change
in median value for each of the variables, over the last
three years.
Total phosphorus concentrations are decreasing in Lake
Burragorang (DWA2), Lower Cascade (DLC1) and
Nepean (DNE2) reservoirs but are increasing at two
locations in the Shoalhaven System: Tallowa Dam (DTA1)
and Fitzroy Falls (DFF6). Other reservoirs showed no
significant trends in total phosphorus concentration.
Total nitrogen is declining in Nepean (DNE2) and
Woronora (DWO1) reservoirs but increasing in Cordeaux
(DCO1) and Lower Cascade (DLC1) reservoirs.
Other reservoirs showed no significant trends in total
nitrogen concentration.
5.1.3 Dissolved oxygen and pH
5.1.1 Chlorophyll–a
A significant trend in chlorophyll–a concentration
was detected only at Greaves Creek (DGC1) where a
gradual annual increase was apparent. This has not
been accompanied by significant trends in nutrient
concentration and may be attributable to water transfer
from the Fish River Scheme.
The interpretation of trends for dissolved oxygen
saturation and pH is more difficult. Both characteristics
can vary from day to day, and fluctuate depending on
time of day, amount of daylight, the presence of algae
and other factors. The data will be affected by the time
of day when sampled. Over the longer term they are
affected by operational activities such as artificial
destratification.
Nevertheless, the measured dissolved oxygen saturation
has been decreasing in Nepean (DNE2), Lower Cascade
(DLC1) and Fitzroy Falls (DFF6) reservoirs and
increasing in Avon (DAV7) and Upper Cascade (DTC1)
reservoirs.
Significant trends in pH were found for reservoirs in the
Upper Nepean, Woronora and Blue Mountains systems.
Decreasing pH was apparent in Nepean (DNE2)
Reservoir while increases were apparent in Avon (DAV7),
Woronora (DWO1), Greaves Creek (DGC1), Lower
Cascade (DLC1) and Upper Cascade (DTC1). Water
transfers from other reservoirs such as Oberon, together
with artificial destratification, may be increasing pH
values in Blue Mountains reservoirs.
The indicator map of the Shoalhaven system (see Part 1)
indicates the generally good water quality throughout the
catchment, but highlights eutrophication in the reservoirs
and risks to recreational users in the Kangaroo River from
thermotolerant coliforms.
12
13
6
Picnic area tap monitoring
Trend analysis in reservoirs cont’
TABLE 4.2 LONG–TERM WATER QUALITY TRENDS IN SCA RESERVOIRS 1990–2002
System
Warragamba
Site
DWA2
RPR1
Chlorophyll–a
µg/L
nst
nst
Upper Nepean & Woronora
DNE2
DAV7
DCO1
DCA1
DWO1
nst
nst
nst
nst
nst
–0.003 ± 0.001
nst
nst
nst
nst
–0.017 ± 0.003
nst
0.006 ± 0.002
nst
–0.002 ± 0.001
–1.57 ± 0.78
0.67 ± 0.34
nst
nst
nst
–0.044 ± 0.027
0.030 ± 0.016
nst
nst
0.044 ± 0.013
Blue Mountains
DGC1
DLC1
DTC1
0.25 ± 0.09
nst
nst
nst
–0.002 ± 0.001
nst
nst
0.005 ± 0.002
nst
nst
–0.40 ± 0.16
0.77 ± 0.37
0.085 ± 0.019
0.062 ± 0.020
0.074 ± 0.029
DTA8
DFF6
DWI1
nst
nst
nst
0.0013 ± 0.0005
0.0002 ± 0.0001
nst
nst
nst
nst
nst
–0.26 ± 0.11
nst
nst
nst
nst
Shoalhaven
Total P
mg/L
–0.0008 ± 0.0004
nst
Total N
mg/L
nst
nst
DO
% saturation
nst
nst
pH
nst
nst
nst: No Significant Trend
TABLE 4.3 YEARLY COMPARISON ON MEDIAN VALUES OF EACH WATER QUALITY VARIABLES
System
Warragamba
Site
DWA2
RPR1
Upper Nepean
& Woronora
DNE2
DAV7
DCA1
DCO1
DWO1
Blue Mountains
DGC1
DLC1
DTC1
Shoalhaven
DTA8
DFF6
DWI1
Year
1999–00
2000–01
2001–02
1999–00
2000–01
2001–02
Chlorophyll–a
(µg/L)
2.9
2.5
2.3
3.0
2.8
2.5
Total N
(mg/L)
0.33
0.28
0.26
0.31
0.26
0.27
Total P
(mg/L)
0.007
0.006
0.004
0.006
0.006
0.006
1999–00
2000–01
2001–02
1999–00
2000–01
2001–02
1999–00
2000–01
2001–02
1999–00
2000–01
2001–02
1999–00
2000–01
2001–02
2.0
1.6
1.7
1.0
1.3
1.5
1.7
1.1
1.5
2.3
1.5
2.0
1.7
1.1
1.5
3.5
3.2
2.0
5.1
4.9
3.3
4.7
3.9
4.0
5.7
5.5
4.7
1.3
1.0
1.4
0.39
0.35
0.33
0.23
0.20
0.20
0.22
0.20
0.24
0.28
0.24
0.29
0.22
0.22
0.21
0.009
0.009
0.007
0.006
0.006
0.005
0.005
0.005
0.006
0.009
0.006
0.007
0.004
0.004
0.004
1
0
1
1
1
0
1
0
1
2
1
0
1
0
0
1999–00
2000–01
2001–02
1999–00
2000–01
2001–02
1999–00
2000–01
2001–02
2.1
1.6
2.0
1.7
1.6
1.6
1.5
1.5
1.5
3.3
2.2
5.3
2.5
2.3
1.7
5.2
6.8
5.0
0.20
0.20
0.17
0.25
0.25
0.26
0.35
0.32
0.34
0.008
0.007
0.004
0.005
0.006
0.003
0.007
0.009
0.007
2
3
5
3
4
4
4
2
4
1999–00
2000–01
2001–02
1999–00
2000–01
2001–02
1999–00
2000–01
2001–02
5.1
4.1
5.3
3.4
2.8
4.0
4.4
2.8
4.7
11.6
6.8
6.8
6.5
5.7
10.7
8.2
5.7
6.8
0.35
0.32
0.37
0.42
0.36
0.50
0.39
0.35
0.44
0.023
0.022
0.023
0.014
0.014
0.014
0.016
0.015
0.015
69
22
54
1
0
1
2
1
4
14
Thermotolerant
coliforms
(CFU/100ml)
1
1
0
2
1
1
Turbidity
(NTU)
1.1
0.9
1.7
1.6
1.6
1.7
6.1 INTRODUCTION
The SCA maintains popular recreational areas near most
reservoirs for local residents and visitors. The SCA is
responsible for providing the drinking water to all of its
picnic areas. The quality of the water supplied in picnic
areas at Avon, Cataract, Cordeaux and Fitzroy Falls
reservoirs and at Bendeela Camping area, is monitored
because the water supplied at these locations is not
treated at a WFP.
Turbidity at SCA picnic area taps was within the
guideline levels on all occasions.
During 2001–2002, supplies were monitored weekly
and the water quality assessed against the NHMRC
(1996) drinking water quality guidelines for public health
and aesthetics.
The NHMRC guidelines state that thermotolerant
coliforms should not be detectable in drinking water on
more than two per cent of occasions. All sites were
within this guideline except for Cataract Picnic Area
(HCA1) where thermotolerant coliforms were detected
on eight per cent of occasions.
The NHMRC recommends that a residual chlorine
concentration of 0.2 to 0.5 milligrams per litre after a
contact time of 30 minutes should be sufficient for
disinfection. The contact times at picnic area sites is
difficult to measure but may be short during peak
demand periods such as at weekends and on public
holidays. Chlorine residuals below 0.5 milligrams per
litre were frequently recorded at picnic area taps.
NSW Health and the World Health Organisation have
indicated that new guidelines should apply to the
monitoring of water quality at picnic area taps. This
changes the focus towards the monitoring of e–coli at the
service reservoir, rather than residual chlorine and
coliform levels at the tap.
Responding to the perceived risk, the SCA has developed
drinking water safety plans in conjunction with
NSW Health for its picnic area supplies. The main
implication for the SCA is that it must ensure correct
dosing of chlorine is provided and that sufficient contact
time is provided in the service reservoir, for disinfection
to occur.
The aesthetic quality of the tap waters was satisfactory.
The pH was within guidelines on all occasions at
Cordeaux and Fitzroy Falls picnic areas, but was
occasionally outside the guideline range at Avon and
Cataract picnic areas (five per cent and seven per cent of
occasions respectively). Colour was within the guideline
values on all occasions at Avon, but occasionally
exceeded the guideline at Cataract, Cordeaux and Fitzroy
Falls picnic areas (four per cent, eight per cent and one
per cent of occasions respectively).
Overall, water quality in picnic area taps had
improved since 2000–2001, with a lower frequency
of guideline exceedances.
15
7
Cyanobacteria monitoring
7.1 INTRODUCTION
Regular monitoring for cyanobacteria was undertaken in
the reservoirs managed by the SCA. The SCA’s Bulk Water
Quality Incident Response Plan (SCA, 2000) specifies
guideline concentration for cyanobacteria at
15 000 cells/mL, and for toxigenic cyanobacteria at
2000 cells/mL.
Cyanobacteria did not exceed guideline concentrations at
Upper Cascade (DTC1), Lower Cascade (DLC1), Nepean
(DNE2) or Woronora reservoirs (DWO1). Cyanobacteria
were detected above guideline concentrations on at least
one occasion at all other reservoirs with very frequent
exceedance of the guideline (greater than 75 per cent of
observations) at a number of sampling sites, mainly in the
Shoalhaven System. Cyanobacteria frequently occurred with
elevated nutrients, particularly phosphorus, suggesting that
limiting phosphorus concentration in these waters can
control cyanobacterial growth. Cyanobacterial occurrence
was generally similar to the 2000–2001 data.
Cyanobacteria exceeded guideline levels infrequently (less
than 25 per cent of observations) at Greaves Creek
(DGC1), Cataract (DCA1) and Lake Yarrunga Shoalhaven
Arm 7 kilometres upstream (DTA5).
They exceeded guidelines regularly (25–50 per cent of
observations) at Avon (DAV7), Cordeaux (DCO1), Lake
Burragorang 300 metres upstream from the dam wall
(DWA2), Lake Yarrunga at Bendeela Power Station (DTA8)
and Lake Yarrunga Kangaroo River arm at Reed Island
(DTA10).
Frequent exceedances (50–75 per cent of observations)
were seen at Lake Yarrunga near the dam wall (DTA1),
Lake Yarrunga Kangaroo River arm at Yarrunga Junction
(DTA3), Prospect Reservoir (RPR1 and RPR3), Lake
Burragorang at Junction 14 kilometres upstream of the dam
wall (DWA9), Lake Burragorang Coxs River arm 24
kilometres upstream (DWA12) and Lake Burragorang
Wollondilly River arm at Tonalli (DWA39).
Very frequent exceedances (75–100 per cent of
observations) were seen at Wingecarribee Reservoir
(DWI1), Fitzroy Falls Reservoir (DFF6), Lake Burragorang
Coxs River arm 36 and 37 kilometres upstream (DWA19,
DWA21) and Lake Burragorang Wollondilly River arm 23
kilometres upstream (DWA27).
Toxigenic cyanobacteria were identified at Fitzroy Falls
Reservoir (DFF6), Lake Yarrunga (DTA1, DTA8),
Wingecarribee Reservoir (DWI1) and Prospect Reservoir
(RPR1). Toxigenic cyanobacteria were detected above
guideline concentrations on a total of twelve occasions,
however the level of microcystin-LR toxicity was always
within guideline levels.
In addition to the routine monitoring, 15 sites
(7 additional) are monitored on a weekly basis from
October to May each year as part of a summer sampling
program. This program may be extended if measured levels
exceed certain trigger levels.
16
Part 4: Monitoring for Operations & Planning
Acknowledgements:
page 2
Contents
1
4
2
About this report
4
3
Catchment monitoring
5
4
5
3.1
Managing Sydney’s water supply catchments
5
3.2
Results
5
3.3
Performance assessment – all catchments
9
Lake monitoring
4.1
Results
10
4.2
15
Trend analysis in reservoirs
5.1
6
7
8
10
18
Long-term trends
18
Picnic area tap monitoring
21
6.1
Introduction
21
6.2
21
Cyanobacteria monitoring
22
7.1
Introduction
22
7.2
22
References
24
page 3
supply.
The SCA’s task is to supply quality bulk raw water to its customers, which include Sydney Water
NSW's population.
2 About this report
This report is Part 4 of the Sydney Catchment Authority’s annual water quality monitoring report,
2001–2002. This part presents detailed technical results for the monitoring program undertaken for
operational and planning purposes. The monitoring data has been compared with guidelines from
the Bulk Water Supply Agreement (BWSA) (Table 1) as an indication of water quality, however
there are no compliance requirements for operating and planning data.
2001 to June 2002.
page 4
Part 4 – Table 1: Water quality guidelines for catchments and reservoirs
Analytes (Unit)
Catchments
Reservoirs
90–110
90–110
pH (pH unit)
6.5-8.0
6.9-8.1* (LB)
6.0-7.2** (O)
Turbidity (NTU)
25
20
Total Iron (mg/L)
na
0.3
na
0.1
na
0.2
0.050
0.010
0.50
0.35
150
100
7
5
na
15000
na
2000
(mm2/L)
na
2
Notes: * LB = Lake Burragorang and Prospect Reservoir; ** O = other lakes. na = not applicable
3 Catchment monitoring
3.1 Managing Sydney’s water supply catchments
The SCA’s bulk water supply is drawn from the catchments of five major river systems in:
Warragamba
Upper Nepean
Woronora
Shoalhaven, and
the Blue Mountains.
These catchments span 18 local government areas covering an area of almost 16 000 square
kilometres. Part 1 of this report provides a detailed description of each catchment area, reservoir,
delivery system and sampling sites.
3.2 Results
page 5
3.2.1
Warragamba Catchment
As in 2000–2001, the quality of inflows close to Lake Burragorang was generally good, meeting
guideline concentrations on most sampling occasions. Outer catchment sites more frequently failed
to meet the guidelines, particularly with respect to pH and dissolved oxygen.
Coxs River (E083) showed good water quality with only one sample recording dissolved oxygen
outside the guideline range in dry weather. Wet weather sampling indicated pH values exceeding
the guideline on one of two occasions and total nitrogen exceeded the guideline value on 60 per
cent of occasions (6 samples). The frequency of readings outside guideline ranges decreased
relative to the 2000–2001 data for pH, dissolved oxygen, turbidity, thermotolerant coliforms and
total nitrogen.
The lower Nattai River (E210) showed generally good water quality in dry weather with all
monitoring data within guidelines except for turbidity, thermotolerant coliforms and total
phosphorus on one occasion and total nitrogen on two occasions. The lower dry weather coliform
concentrations observed in 2000–2001 continued in 2001–2002 and can be attributed to the recent
upgrading of the Mittagong Sewage Treatment Plant (STP). Wet weather samples were outside
guideline ranges with greater frequency than in 2000–2001 for dissolved oxygen, turbidity,
thermotolerant coliforms, total nitrogen and total phosphorus. Chlorophyll-a was not detected
above the guideline in 2001–2002.
The upper Nattai River (E206) water quality was outside guideline ranges on fewer occasions than
in 2000–2001, although total nitrogen and total phosphorus were regularly above guideline levels
and dissolved oxygen was below the guideline range on 50 per cent of occasions. Wet weather
water quality was also outside guideline ranges for turbidity, thermotolerant coliforms, total
phosphorus and chlorophyll-a on fewer occasions than in 2000–2001. Dissolved oxygen and total
nitrogen were outside guideline ranges at a similar frequency to that observed in 2000–2001 (50
per cent and 100 per cent respectively).
The lower Wollondilly River (E488) showed improved total nitrogen concentration with no
guideline exceedances in dry weather. However, dissolved oxygen measurements were outside the
guideline ranges more frequently in dry weather than in 2000–2001. Wet weather samples showed
a significant reduction in the frequency of guideline exceedance for thermotolerant coliforms and
an increase in frequency for total nitrogen, total phosphorus and chlorophyll-a. The central
Wollondilly River (E450) showed similar dry weather water quality to that in 2000–2001, except
that thermotolerant coliforms were always within the guidelines in 2001–2002.
In the upper Wollondilly River (E409) and Mulwaree River (E457), dry weather water quality
deteriorated relative to 2000–2001, with pH, dissolved oxygen, total phosphorus, total nitrogen
and chlorophyll-a regularly outside the guideline ranges. However, wet weather water quality
improved with respect to turbidity and chlorophyll-a while the frequency of guideline exceedance
page 6
for thermotolerant coliforms, total nitrogen and total phosphorus was similar to that observed in
2000–2001 (50 per cent, 100 per cent and 100 per cent respectively). No wet weather data for pH
or dissolved oxygen was available in 2001–2002.
Similar conditions were observed in the Wingecarribee River (E332) although turbidity and
chlorophyll-a exceeded guideline concentrations at a greater frequency than in the Wollondilly
River. This suggests that elevated nutrient levels in the Wingecarribee, Mulwaree and upper
Wollondilly rivers are encouraging algal growth, with consequent consumption of dissolved
oxygen and elevation of pH. The upper Wollondilly River is affected by a number of treated
wastewater discharges in and around Goulburn that may be a source of elevated nutrients. The
upper Wingecarribee River experiences elevated nutrient levels from fertilisers used in the
catchment, although monitoring in Wingecarribee Swamp suggests the swamp is filtering
Dry weather water quality declined slightly in Little River (E243) from 2000–2001 with pH,
dissolved oxygen and total nitrogen falling outside guideline ranges occasionally. Wet weather
sampling declined also, with turbidity, total nitrogen and total phosphorus exceeding guidelines
more often than in 2000–2001.
Dissolved oxygen was outside the guidelines in the Kowmung River (E130) in dry weather more
often than last year, while thermotolerant coliforms exceeded guideline levels on one occasion
only in dry weather. Wet weather data for this location showed an increased incidence of
thermotolerant coliforms and total nitrogen exceeding guideline concentrations.
Sampling in the Kedumba River (E157) showed fewer exceedances of total nitrogen but a slight
increase in turbidity, dissolved oxygen and total phosphorus exceedances. Wet weather sampling
showed fewer exceedances of dissolved oxygen and thermotolerant coliform guidelines, but more
exceedances of pH, turbidity, total nitrogen and total phosphorus than in 2000–2001.
Werriberri Creek (E531) showed a reduced frequency of dissolved oxygen and chlorophyll-a
concentrations outside the guideline ranges in dry weather, with dissolved oxygen below the
guideline range on 91 per cent of occasions and chlorophyll-a not present above guideline levels.
Dissolved oxygen was depleted at this location on all occasions in 2000–2001. A slight increase in
exceedance frequency was observed for thermotolerant coliforms, total nitrogen and total
phosphorus. Wet weather monitoring indicated a decline in water quality with a slight increase in
exceedance frequency for dissolved oxygen depletion, thermotolerant coliforms, total nitrogen and
chlorophyll-a.
The Oaks township is unsewered and is a possible source of thermotolerant coliform and nutrient
contamination in Werriberri Creek. The elevated nutrient levels would provide good conditions for
algal growth and may contribute to the elevated chlorophyll-a concentrations and depleted
page 7
dissolved oxygen observed in the creek. A reticulated sewerage system, which would reduce these
impacts, is currently under construction.
DAPI-positive Giardia cysts were detected in dry weather in Kowmung and Kedumba rivers and
in Gibbergunyah Creek but not in Lake Burragorang. They were not detected during wet weather.
Those from Gibbergunyah Creek are probably from the Mittagong STP which lies upstream of the
sampling point, which would explain the relatively high numbers of cysts detected (up to 576
cysts/100 litre). Low levels of DAPI-positive Cryptosporidium oocysts were detected in Werriberri
Creek (E531) in both wet and dry weather (possibly from The Oaks township), and on two
occasions in Lake Burragorang.
3.2.2
Nepean Catchment
The Nepean (E601) and Burke (E602) rivers are the two major inflows into Lake Nepean. The dry
weather water quality of the Nepean River remained good, with no guideline exceedances except
for total nitrogen in five out of eight sampling events. This frequency of exceedance is higher than
in 2000–2001. Wet weather water quality improved in comparison to the 2000–2001 data, with
fewer guideline exceedances for turbidity (eight per cent), thermotolerant coliforms (33 per cent),
total nitrogen (71 per cent) and total phosphorus (nine per cent).
Dry weather water quality in the Burke River was also generally good, with only a slightly
increased proportion of samples having pH and dissolved oxygen measurements outside the
guideline values. Wet weather water quality was generally good, except for occasional noncompliances for dissolved oxygen, turbidity, thermotolerant coliforms, total nitrogen and total
phosphorus. Guideline exceedance frequency was generally similar to that of 2000–2001.
These exceedances are most likely related to agricultural land use within the catchment.
3.2.3
Avon, Cataract, Cordeaux, Woronora and Blue Mountains Catchments
These catchments are predominantly bushland and so require no water quality monitoring sites.
Water quality is monitored in the reservoirs and delivery systems only.
3.2.4
Lake Yarrunga (Shoalhaven) Catchment
Dry weather water quality within the Shoalhaven catchment was generally within guideline
concentrations, except for dissolved oxygen, which was below guideline concentrations on
numerous occasions in all monitoring locations, and total nitrogen in Boro Creek (E890), which
exceeded guideline concentrations on 18 per cent of occasions. Guidelines were exceeded more
frequently than in 2000–2001.
Water quality in the catchment deteriorated during wet weather. Chlorophyll-a regularly remained
within guideline levels except in the Kangaroo River (E706), Central Shoalhaven River (E861)
page 8
and Gillamatong Creek (E891). Dissolved oxygen was frequently below guideline concentrations
at all sites except Boro Creek (E890). Turbidity was frequently poor in wet weather throughout the
catchment, with the exceptions of Gillamatong Creek (E891), Mongarlowe River (E822) and in the
Shoalhaven River downstream of its confluence with the Marlowe River (E861). Concentrations of
thermotolerant coliforms and nutrients (total nitrogen or total phosphorus) frequently exceeded
guideline levels in wet weather at all locations. Nutrients and chlorophyll-a across the catchment
exceeded guidelines more frequently than in 2000–2001. Dissolved oxygen and thermotolerant
coliforms concentrations exceeded guidelines more frequently or remained similar to those in
2000–2001.
The observed impacts on water quality can be attributed to the land uses within the catchment
(detailed in Part 1).
3.3 Performance assessment – all catchments
Water quality in the catchments was compared to guidelines specified by ANZECC (2000) for
dissolved oxygen, pH, turbidity and thermotolerant coliforms, and by the Healthy Rivers
Commission (1998) for total phosphorus, total nitrogen and chlorophyll-a.
Water quality in the Warragamba catchment was generally good, complying with water quality
guidelines on most sampling occasions at the inflows to Lake Burragorang. Water quality in the
outer catchment sites was not as good, with more frequent exceedances of guidelines for pH,
dissolved oxygen, nutrients and chlorophyll-a. Water quality generally deteriorated in wet weather.
Water quality in the Nepean catchment was good, with dry weather guideline exceedances limited
to total nitrogen in the Nepean River, and pH and dissolved oxygen in the Burke River. Wet
weather sampling showed poorer water quality in both rivers, particularly for turbidity,
thermotolerant coliforms and nutrients.
Water quality in the Shoalhaven catchment was generally very good, except for frequently
depleted levels of dissolved oxygen throughout the catchment during dry weather. Total nitrogen
exceeded guideline concentrations at Boro Creek on several occasions. Wet weather samples
showed poorer water quality than in dry weather, with higher levels of turbidity, thermotolerant
coliforms and nutrient concentrations. Chlorophyll-a exceeded the guidelines during wet weather
in the Kangaroo and central Shoalhaven rivers and in Gillamatong Creek.
page 9
4 Lake monitoring
4.1 Results
4.1.1
Lake Burragorang
Water quality in Lake Burragorang was generally good throughout the year, with thermotolerant
coliforms below guideline levels at all times. Turbidity was at or below guideline levels for 99 per
cent of the time. Some other characteristics exceeded guidelines, however, as outlined below.
Cyanobacteria were frequently present in excess of guideline concentrations at all locations within
Lake Burragorang (42–92 per cent of occasions). Toxigenic cyanobacteria were detected at some
of the sampling sites within Lake Burragorang but were rarely above guideline concentrations.
Dissolved oxygen concentrations were outside guidelines in 26 per cent (DWA9, Warragamba
Dam) to 84 per cent (DWA27, Wollondilly Arm, 23 kilometres upstream of Warragamba Dam at
Bimlow) of samples, largely from supersaturation of the water. Supersaturation may indicate
excessive plant or algal growth but is unlikely to directly threaten aquatic biota. Supersaturation
may also result from wind action and was observed on numerous occasions in reservoirs in 2000–
2001.
Dissolved oxygen was depleted at some sites, but was not recorded below 68 per cent at any site.
While depleted dissolved oxygen can threaten biota in reservoirs, any risk can be reduced with
artificial destratification systems such as those in place in a number of SCA reservoirs.
The chlorophyll-a guideline level (5 micrograms per litre) was regularly exceeded by a small
amount at some sites, with a recorded maximum at any site of 19 micrograms per litre. For
instance, 67 per cent of observations in the Coxs River arm 36 kilometres upstream of the dam
wall (DWA19), 32 per cent in the Coxs River arm 37 kilometres upstream of the dam wall
(DWA21) and 30 per cent in the Wollondilly River arm at Tonalli (DWA39), were above the
guideline level. High chlorophyll-a concentrations occurred many kilometres upstream and posed
little threat to water quality at the dam.
Sites complied with total phosphorus guidelines at least 93 per cent of the time except for the sites
DWA19, DWA21 and DWA39, which had 33 per cent, 40 per cent and 70 per cent compliance
respectively. These are the same sites with elevated chlorophyll-a concentrations and were all
many kilometres from the dam wall. Total nitrogen guidelines were infrequently exceeded (on up
to 7 per cent of occasions) in locations away from the dam wall.
page 10
The exceedance rates for pH were generally greater than in 2000–2001, although the maximum
and minimum pH values observed were within 1 pH unit of the guideline range in all cases.
Overall, pH tended to be alkaline rather than acidic. The observed pH, nutrient, cyanobacteria and
chlorophyll-a concentrations indicate the potential for problem algal growth in Lake Burragorang.
Cryptosporidium oocysts were detected at low levels (7 oocycts/100 litres) at a site within Lake
Burragorang (DWA2) on three occasions during November and December 2001, two of which
returned positive DAPI tests. The single Giardia cyst detected was not DAPI-positive.
In summary, all characteristics were generally consistent with 2000–2001 results except for pH
and cyanobacteria, which were outside guideline concentrations more frequently than in 2000–
2001, and minor instances of Cryptosporidium oocysts which were not detected at all in 2000–
2001.
4.1.2
Prospect Reservoir
At the two sites in Prospect Reservoir (RPR1, RPR3), water quality was generally good. Water
quality close to the pumping station at the end of the south-western arm (RPR3) was within
guideline concentrations except when turbidity exceeded its guideline on one occasion and
cyanobacteria on 83 per cent of occasions. Toxigenic cyanobacteria were detected, but never
above guideline concentrations.
At the mid-lake site (RPR1), pH and cyanobacteria were frequently outside guideline ranges,
although toxigenic cyanobacteria when detected were below guideline concentrations and pH was
within 1 pH unit of the guidelines at all times. Dissolved oxygen was occasionally outside the
guideline ranges, and total nitrogen exceeded the guidelines on one occasion.
Cyanobacteria counts exceeded guideline concentrations at both sites more frequently than in
2000–2001, as did the pH at RPR1 and turbidity at RPR3. However, no instances of elevated
chlorophyll-a at RPR1 or total nitrogen at RPR3 were seen this year, unlike 2000–2001. Other
characteristics remained consistent with 2000–2001 measurements.
4.1.3
Nepean Reservoir
Water quality in the Nepean Reservoir was generally good, with exceedance frequencies for total
nitrogen, chlorophyll-a and cyanobacteria decreasing relative to 2000–2001. However, dissolved
oxygen and pH were frequently outside the guideline ranges. Thermotolerant coliforms were
detected above guideline concentrations on one occasion. Total iron and total manganese exceeded
the guideline concentrations on a number of occasions, continuing a pattern observed in 2000–
2001. Exceedance frequencies for these metals in 2001–2002 were however slightly higher.
page 11
Water quality in this reservoir is known to be susceptible to wet weather impacts due its
proportionally larger catchment area. The observed increases in turbidity and total metals are
typical of these impacts.
The depleted dissolved oxygen concentrations observed at this location are related to thermal
stratification of the reservoir (see Part 1), which can also result in elevated metal concentrations. A
lake aerator has been used during the warmer months since 1995 to help combat this problem.
Total cyanobacteria counts exceeded the guidelines; however, no toxigenic cyanobacteria were
detected.
4.1.4
Avon Reservoir
The relatively small Avon Reservoir catchment comprises highly protected land and mainly
bushland. Consequently, there are no catchment monitoring sites for this reservoir. Water quality
sampling is conducted at the junction of two channels which flow into the main lake at Upper
Avon (DAV7). It is from this point that water is abstracted to supply the Illawarra region.
The most frequent exceedances of guideline values were dissolved oxygen (48 per cent) and
cyanobacteria (40 per cent). No toxigenic cyanobacteria were detected. Chlorophyll-a exceeded
guideline concentrations on only 12 per cent of occasions, less frequently than in 2000–2001.
Nutrients (total nitrogen) and particulate metals were occasionally above guideline concentrations.
The monitoring site is known to be susceptible to increases in turbidity and particulate metal
concentrations after wet weather. These effects have been observed to persist for only a few days
after a wet weather event.
The pH was occasionally elevated and dissolved oxygen was outside guideline ranges on 58 per
cent of occasions, probably resulting from excessive algal growth.
Total cyanobacteria counts exceeded the guidelines, however toxigenic cyanobacteria were
detected only twice, and were well below the guidelines on both occasions.
4.1.5
Cataract and Cordeaux Reservoirs
Cataract (DCA1) and Cordeaux (DCO1) reservoirs are similar both in size and water quality
characteristics. Both storages discharge to the Upper Canal Delivery System. Cataract Reservoir
discharges to the Cataract River, about 10 kilometres upstream of Broughtons Pass. Cordeaux
Reservoir discharges to the Cordeaux River, 20 kilometres upstream of Pheasants Nest Weir which
diverts water through a tunnel to Broughtons Pass Weir.
Water quality in the upper 12 metres of these reservoirs was monitored regularly, and was found to
be generally within the guideline levels for most characteristics.
page 12
Cyanobacteria and chlorophyll-a concentrations exceeded guidelines on three occasions in
Cataract Reservoir and four in Cordeaux Reservoir during the warmer months (November 2001 to
April 2002). These occurrences were more frequent than in 2000–2001. No toxigenic species were
detected. Nutrient concentrations in Cordeaux Reservoir exceeded guidelines more frequently
than in 2000–2001, which may have provided more favourable conditions for the growth of algae,
leading to the observed chlorophyll-a and cyanobacteria counts.
Thermal stratification resulted in oxygen depletion in the bottom layers of the lakes with
subsequent diffusion of iron and manganese from the sediments into the deep lake water. As the
reservoirs are not artificially destratified, natural mixing in autumn results in peak metal
concentrations and depleted oxygen near the surface. A similar pattern was observed in 2000–
2001.
4.1.6
Woronora Reservoir
The water of Woronora Reservoir is relatively low in alkalinity, and is slightly more acidic than
the waters of the other reservoirs, a characteristic of its catchment. Water quality was good, and
generally similar to that observed in 2000–2001. Chlorophyll-a and cyanobacteria were within
guideline concentrations at all times. No toxigenic cyanobacteria were detected.
Turbidity and pH were also good, with only 2 per cent and 1 per cent of measurements
respectively being outside guideline values.
Dissolved oxygen was similar to that observed in 2000–2001, with 33 per cent of observations
outside the guideline range. Depleted dissolved oxygen levels occurred in cooler months and may
be related to destratification of the reservoir. Supersaturation in summer months could be related to
aquatic plant growth (which was within guideline levels), to wind action, or both.
Total iron and total manganese exceeded the guideline concentrations on one occasion in autumn,
probably because of natural seasonal mixing of the reservoir.
4.1.7
Blue Mountains Reservoirs
Monitoring was conducted in the Upper Cascade (DTC1), Lower Cascade (DLC1) and Greaves
Creek (DGC1) reservoirs. The monitoring points are close to the water supply offtakes.
Water quality in the Blue Mountains reservoirs was good in 2001–2002. At Lower Cascade
(DLC1) pH exceeded the guideline on 83 per cent of occasions but by no more than a small
margin (a maximum of 0.8 pH units). Dissolved oxygen fell below the guidelines on only two
occasions (14 per cent of samples).
Chlorophyll-a exceeded guideline concentrations in Upper Cascade (DTC1) less often than in
2000–2001, possibly because of water being diverted from the Fish River Scheme. The maximum
page 13
cyanobacteria concentration decreased from 11 000 cells per millilitre (cells/mL) in 2000–2001 to
5277 cells/mL in 2001–2002, and on no occasion exceeded the guideline level. Toxigenic cells
were detected only three times throughout the year, and only at very low levels (53 cells/mL
maximum). Total phosphorus exceeded the guideline level less often than in 2000–2001, but total
nitrogen exceeded the guidelines more often.
At Greaves Creek (DGC1), water quality was also good, except for consistently elevated
concentrations of total iron, which exceeded guideline concentrations on all occasions as in 2000–
2001. Chlorophyll-a exceeded the guidelines more frequently than in 2000–2001. Dissolved
oxygen was below the guideline range on 40 per cent of occasions, which is less frequently than in
2000–2001. Total cyanobacteria numbers exceeded the guidelines only once throughout the year
and on the one occasion that toxigenic cells were detected, they were at a very low level (12
cells/mL).
4.1.8
Lake Yarrunga
Lake Yarrunga on the Shoalhaven River had poorer water quality than the other reservoirs
managed by SCA. The lake stratifies in summer resulting in depleted dissolved oxygen and
elevated nutrients and metals in the bottom layer, particularly in the deeper locations of the Dam
Wall (DTA1) and Yarrunga Junction (DTA3). Seasonal mixing of the lake brings this poorer
quality water to the surface. The maximum total iron concentration of 12.91 milligrams per litre
was observed at DTA3 in May 2002, consistent with natural autumnal destratification.
Total phosphorus (82 times or 100 per cent of occasions) and total nitrogen (61 times or 91 per
cent of occasions) almost always exceeded the guidelines. Elevated nutrient concentrations are
consistent with regular chlorophyll-a and cyanobacteria counts above guideline concentrations at
all sites. Levels of toxigenic cyanobacteria detected at DTA1 and DTA8 had microcystin-LR
toxicity equivalents of 0.3 and 0.4 micrograms per litre respectively and were well below the
guideline value (1.3 micrograms per litre).
Across all sites, thermotolerant coliforms were detected above guideline concentrations in 10–33
per cent of observations.
Although pH exceeded guidelines regularly at all locations, the values were all within 0.5 pH units
of the guideline for reservoirs (pH 7.2), with the maximum pH of all sites (pH 7.7) observed at
DTA3. The neutral to mildly alkaline nature of these waters is not a problem, and the results are
consistent with those obtained in 2000–2001.
4.1.9
Fitzroy Falls Reservoir
The Fitzroy Falls Reservoir is relatively shallow (average depth 4.5 metres) and is therefore less
prone to thermal stratification. Consequently, metals concentrations were below guideline levels
on all occasions.
page 14
However, the nutrient loading was high with nearly all observations for total nitrogen and total
phosphorus exceeding the guideline values. Algal growth was abundant under these conditions
with chlorophyll-a exceeding guidelines on 94 per cent of occasions and cyanobacteria levels
exceeding guidelines on all occasions. Toxigenic cyanobacteria were detected exceeding the
guideline level of 2000 cells/mL for 25 per cent of the time, but microcystin-LR toxicity
equivalents were 0.8 micrograms per litre or less, well below guideline levels. This pattern is
similar to the 2000–2001 results except that nutrients and chlorophyll-a exceeded guideline levels
more frequently in 2001–2002.
Dissolved oxygen was depleted (below the guideline range) on 50 per cent of occasions, more
frequently than in 2000–2001, and pH was elevated slightly above guideline concentrations on 96
per cent of occasions (similar to 2000–2001). These measurements are consistent with the
observed abundance of algal growth.
4.1.10 Wingecarribee Reservoir
Wingecarribee Reservoir (DWI1) is another shallow reservoir, having a maximum depth of 12
metres. It is not prone to thermal stratification, with the result that metals concentrations remained
below guidelines throughout the year.
However, nutrient levels were high, with total nitrogen exceeding the guideline concentrations on
90 per cent of occasions and total phosphorus exceeding guidelines on all occasions. Chlorophyll-a
and cyanobacteria exceeded guidelines on 82 per cent and 96 per cent of occasions respectively.
Low levels of toxigenic cyanobacteria (microcystin-LR toxicity equivalents of 0.5 micrograms per
litre or less, well below guideline levels) were detected from February 2002 to June 2002.
The peat mass of Wingecarribee Swamp and upstream agricultural land use are known to
contribute to elevated total nitrogen, total phosphorus and chlorophyll-a in the Wingecarribee
River, and most likely explain the observed water quality impacts.
Similar to the pattern observed at Fitzroy Falls Reservoir, dissolved oxygen was depleted on 27
per cent of occasions, more frequently than in 2000–2001, and pH was elevated slightly above
guideline concentration on all occasions (similar to 2000–2001). These measurements are
consistent with the observed abundance of algal growth.
4.2 Performance assessment
Water quality in Lake Burragorang was generally good throughout the year. However, nontoxigenic cyanobacteria were regularly detected above guideline concentrations at all locations
throughout the year. Dissolved oxygen concentrations regularly exceeded the guideline at two
locations, DWA9 and DWA27, 14 and 23 kilometres upstream of the dam wall. Chlorophyll-a and
total phosphorus regularly exceeded guidelines in areas well upstream of the dam wall. They are
page 15
not considered to have affected the quality of the water supply. The pH was within 1 pH unit of the
guideline range in all samples, but tended to be too alkaline.
Prospect Reservoir showed generally good water quality throughout the year despite minor
exceedances of turbidity, pH, dissolved oxygen and cyanobacteria concentrations.
The indicator map of the Warragamba system (see Part 1) illustrates the general performance of
aesthetics, eutrophication, recreation (catchment sites) and bacteriological health (reservoirs), as
outlined above. Of note are the eutrophication indicators in the upper Wollondilly and
Wingecarribee rivers and the outer parts of Lake Burragorang.
The Nepean Reservoir showed generally good water quality, with improved frequency of
compliance for nutrients, chlorophyll-a and cyanobacteria, although dissolved oxygen and pH
were regularly outside guideline ranges. A lake aerator treats thermal stratification at the site;
nonetheless, elevated metal concentrations were detected at a greater frequency than in 2000–
2001.
Avon Reservoir too showed generally good water quality, but concentrations of dissolved oxygen
and cyanobacteria outside guideline values were common. Toxigenic cyanobacteria were detected,
but within guideline levels. Nutrient, metals and pH occasionally exceeded guideline
concentrations.
Water quality in the Cataract and Cordeaux reservoirs was generally within guidelines on all
occasions. Nutrients, chlorophyll-a and cyanobacteria were occasionally outside guideline
concentrations. A pattern of thermal stratification was observed which affected dissolved oxygen
and metal concentrations in both reservoirs.
Woronora Reservoir had good water quality with only minor exceedances of the turbidity and pH
guidelines; however, dissolved oxygen was regularly outside guideline ranges.
The map of the Upper Nepean and Woronora systems (see Part 1) indicates generally good water
quality throughout the catchment, but highlights the eutrophication found in Avon and Cordeaux
reservoirs.
Water quality in the Blue Mountains reservoirs was good. However, pH regularly exceeded the
guidelines at Lower Cascade by a minor margin. Nutrients and chlorophyll-a exceeded guideline
levels in Upper Cascade, although less frequently than in 2000–2001. The only exception to water
quality guidelines at Greaves Creek was persistently elevated iron concentrations, also observed in
2000–2001.
The indicator map of the Blue Mountains System (see Part 1) highlights eutrophication in the
reservoirs.
page 16
Lake Yarrunga had the poorest water quality of all reservoirs managed by the SCA. Thermal
stratification in the lake led to depleted dissolved oxygen levels and elevated metal concentrations.
Nutrients exceeded the guideline concentrations on almost all occasions. Chlorophyll-a and
Cyanobacteria also frequently exceeded guideline levels, although toxigenic cyanobacteria were
detected only once. Thermotolerant coliforms and pH were also regularly above guideline
concentrations.
Fitzroy Falls and Wingecarribee reservoirs had generally good water quality, although nutrient
concentrations were almost always above guideline concentrations. Chlorophyll-a and
cyanobacteria concentrations were often above guideline concentrations, probably as a result of
nutrient enrichment. Low levels of toxigenic cyanobacteria were frequently detected but remained
within guideline concentrations. Dissolved oxygen and pH were also regularly outside
concentration ranges, probably because of algal growth.
The indicator map of the Shoalhaven system (see Part 1) indicates the generally good water quality
throughout the catchment, but highlights eutrophication in the reservoirs and risks to recreational
users in the Kangaroo River from thermotolerant coliforms.
page 17
5 Trend analysis in reservoirs
5.1 Long-term trends
Five key water quality variables measured at each reservoir offtake site since 1990 were analysed
for trends using linear regression. These were:
chlorophyll-a
total phosphorus
total nitrogen
dissolved oxygen and
pH.
The results are summarised in Table 2. For those sites where a significant trend was detected, the
table lists the typical annual change and standard error relative to this change. Values are given in
the units in which that variable is reported throughout this report. Positive trend values indicate
rising levels, while negative trend values indicate falling levels. Table 3 shows the actual change in
median value for each of the variables, over the last three years.
5.1.1
Chlorophyll-a
A significant trend in chlorophyll-a concentration was detected only at Greaves Creek (DGC1)
where a gradual annual increase was apparent. This has not been accompanied by significant
trends in nutrient concentration and may be attributable to water transfer from the Fish River
Scheme.
5.1.2
Nutrients – total phosphorus and total nitrogen
Trends in nutrient concentrations in reservoirs are affected by the water quality of inflows, which
in turn is determined by land use in the catchments. Rainfall patterns (frequency and intensity) will
also affect the amount and timing of nutrient input into the reservoirs.
Total phosphorus concentrations are decreasing in Lake Burragorang (DWA2), Lower Cascade
(DLC1) and Nepean (DNE2) reservoirs but are increasing at two locations in the Shoalhaven
System: Tallowa Dam (DTA1) and Fitzroy Falls (DFF6). Other reservoirs showed no significant
trends in total phosphorus concentration.
page 18
Total nitrogen is declining in Nepean (DNE2) and Woronora (DWO1) reservoirs but increasing in
Cordeaux (DCO1) and Lower Cascade (DLC1) reservoirs. Other reservoirs showed no significant
trends in total nitrogen concentration.
Part 4 - Table 2 Long-term water quality trends in SCA reservoirs 1990–2002
System
Site
Warragamba
Upper Nepean
& Woronora
Blue Mountains
Shoalhaven
Chlorophyll-a
Total P
Total N
DO
µg/L
mg/L
mg/L
% saturation
DWA2
nst
-0.0008 ± 0.0004
nst
nst
nst
RPR1
nst
nst
nst
nst
nst
DNE2
nst
-0.003 ± 0.001
-0.017 ± 0.003
-1.57 ± 0.78
-0.044 ± 0.027
DAV7
nst
nst
nst
0.67 ± 0.34
0.030 ± 0.016
DCO1
nst
nst
0.006 ± 0.002
nst
nst
DCA1
nst
nst
nst
nst
nst
DWO1
nst
nst
-0.002 ± 0.001
nst
0.044 ± 0.013
DGC1
0.25 ± 0.09
nst
nst
nst
0.085 ± 0.019
DLC1
nst
-0.002 ± 0.001
0.005 ± 0.002
-0.40 ± 0.16
0.062 ± 0.020
DTC1
nst
nst
nst
0.77 ± 0.37
0.074 ± 0.029
DTA8
nst
0.0013 ± 0.0005
nst
nst
nst
DFF6
nst
0.0002 ± 0.0001
nst
-0.26 ± 0.11
nst
DWI1
nst
nst
nst
nst
nst
nst
No Significant Trend
5.1.3
pH
The interpretation of trends for dissolved oxygen saturation and pH is more difficult. Both
characteristics can vary from day to day, and fluctuate depending on time of day, amount of
daylight, the presence of algae and other factors. The data will be affected by time of day when
sampled. Over the longer term they are affected by operational activities such as artificial
destratification.
Nevertheless, the measured dissolved oxygen saturation has been decreasing in Nepean (DNE2),
Lower Cascade (DLC1) and Fitzroy Falls (DFF6) reservoirs and increasing in Avon (DAV7) and
Upper Cascade (DTC1) reservoirs.
Significant trends in pH were found for reservoirs in the Upper Nepean, Woronora and Blue
Mountains systems. Decreasing pH was apparent in Nepean (DNE2) Reservoir while increases
were apparent in Avon (DAV7), Woronora (DWO1), Greaves Creek (DGC1), Lower Cascade
(DLC1) and Upper Cascade (DTC1). Water transfers from other reservoirs such as Oberon,
together with artificial destratification, may be increasing pH values in Blue Mountains reservoirs.
page 19
Part 4 - Table 3 Yearly comparison on median values of each water quality variables
System
Warragamba
Site
DWA2
RPR1
Upper Nepean
DNE2
& Woronora
DAV7
DCA1
DCO1
DWO
1
Blue
DGC1
Mountains
DLC1
DTC1
Shoalhaven
DTA8
DFF6
DWI1
Thermotolerant
coliforms
Turbidity
Chlorophyll-a
Total N
Total P
(NTU)
(µg/L)
(mg/L)
(mg/L)
1999-00
1.1
2.9
0.33
0.007
1
2000-01
0.9
2.5
0.28
0.006
1
2001-02
1.7
2.3
0.26
0.004
0
1999-00
1.6
3.0
0.31
0.006
2
2000-01
1.6
2.8
0.26
0.006
1
2001-02
1.7
2.5
0.27
0.006
1
1999-00
2.0
3.5
0.39
0.009
1
2000-01
1.6
3.2
0.35
0.009
0
2001-02
1.7
2.0
0.33
0.007
1
1999-00
1.0
5.1
0.23
0.006
1
2000-01
1.3
4.9
0.20
0.006
1
2001-02
1.5
3.3
0.20
0.005
0
1999-00
1.7
4.7
0.22
0.005
1
2000-01
1.1
3.9
0.20
0.005
0
2001-02
1.5
4.0
0.24
0.006
1
1999-00
2.3
5.7
0.28
0.009
2
2000-01
1.5
5.5
0.24
0.006
1
2001-02
2.0
4.7
0.29
0.007
0
1999-00
1.7
1.3
0.22
0.004
1
2000-01
1.1
1.0
0.22
0.004
0
2001-02
1.5
1.4
0.21
0.004
0
1999-00
2.1
3.3
0.20
0.008
2
2000-01
1.6
2.2
0.20
0.007
3
2001-02
2.0
5.3
0.17
0.004
5
1999-00
1.7
2.5
0.25
0.005
3
2000-01
1.6
2.3
0.25
0.006
4
2001-02
1.6
1.7
0.26
0.003
4
1999-00
1.5
5.2
0.35
0.007
4
2000-01
1.5
6.8
0.32
0.009
2
Year
(CFU/100ml)
2001-02
1.5
5.0
0.34
0.007
4
1999-00
5.1
11.6
0.35
0.023
69
2000-01
4.1
6.8
0.32
0.022
22
2001-02
5.3
6.8
0.37
0.023
54
1999-00
3.4
6.5
0.42
0.014
1
2000-01
2.8
5.7
0.36
0.014
0
2001-02
4.0
10.7
0.50
0.014
1
1999-00
4.4
8.2
0.39
0.016
2
2000-01
2.8
5.7
0.35
0.015
1
2001-02
4.7
6.8
0.44
0.015
4
page 20
6 Picnic area tap monitoring
6.1 Introduction
The SCA maintains popular recreational areas near most reservoirs for local residents and visitors.
The SCA is responsible for providing the drinking water to all of its picnic areas. The quality of
the water supplied in picnic areas at Avon, Cataract, Cordeaux and Fitzroy Falls reservoirs and at
Bendeela Camping area, is monitored because the water supplied at these locations is not treated at
a WFP.
During 2001–2002, supplies were monitored weekly and the water quality assessed against the
NHMRC (1996) drinking water quality guidelines for public health and aesthetics.
6.2 Results and discussion
Turbidity at SCA picnic area taps was within the guideline levels on all occasions.
The NHMRC guidelines state that thermotolerant coliforms should not be detectable in drinking
water on more than two per cent of occasions. All sites were within this guideline except for
Cataract Picnic Area (HCA1) where thermotolerant coliforms were detected on eight per cent of
occasions.
The NHMRC recommends that a residual chlorine concentration of 0.2 to 0.5 milligrams per litre
after a contact time of 30 minutes should be sufficient for disinfection. The contact times at picnic
area sites is difficult to measure but may be short during peak demand periods such as at weekends
and on public holidays. Chlorine residuals below 0.5 milligrams per litre were frequently recorded
at picnic area taps.
NSW Health and the World Health Organisation have indicated that new guidelines should apply
to the monitoring of water quality at picnic area taps. This changes the focus of monitoring to the
monitoring of e-coli at the service reservoir, in preference to residual chlorine and coliform levels
at the tap.
Responding to the perceived risk, the SCA has developed drinking water safety plans in
conjunction with NSW Health for its picnic area supplies. The main implication for the SCA is
that it must ensure correct dosing of chlorine is provided and that sufficient contact time is
provided in the service reservoir, for disinfection to occur.
page 21
The aesthetic quality of the tap waters was satisfactory. The pH was within guidelines on all
occasions at Cordeaux and Fitzroy Falls picnic areas, but was occasionally outside the guideline
range at Avon and Cataract picnic areas (five per cent and seven per cent of occasions
respectively). Colour was within the guideline values on all occasions at Avon, but occasionally
exceeded the guideline at Cataract, Cordeaux and Fitzroy Falls picnic areas (four per cent, eight
per cent and one per cent of occasions respectively).
Overall, water quality in picnic area taps had improved since 2000–2001, with a lower frequency
of guideline exceedances.
7 Cyanobacteria monitoring
7.1 Introduction
Regular monitoring for cyanobacteria was undertaken in the reservoirs managed by the SCA. The
SCA’s Bulk Water Quality Incident Response Plan (SCA, 2000) specifies guideline concentration
for cyanobacteria at 15 000 cells/mL, and for toxigenic cyanobacteria at 2000 cells/mL.
7.2 Results and discussion
Cyanobacteria did not exceed guideline concentrations at Upper Cascade (DTC1), Lower Cascade
(DLC1), Nepean (DNE2) or Woronora reservoirs (DWO1). Cyanobacteria were detected above
guideline concentrations on at least one occasion at all other reservoirs with very frequent
exceedance of the guideline (greater than 75 per cent of observations) at a number of sampling
sites, mainly in the Shoalhaven System. Cyanobacteria frequently occurred with elevated nutrients,
particularly phosphorus, suggesting that limiting phosphorus concentration in these waters can
control cyanobacterial growth. Cyanobacterial occurrence was generally similar to the 2000–2001
data.
Cyanobacteria exceeded guideline levels infrequently (less than 25 per cent of observations) at
Greaves Creek (DGC1), Cataract (DCA1) and Lake Yarrunga Shoalhaven Arm 7 kilometres
upstream (DTA5).
They exceeded guidelines regularly (25–50 per cent of observations) at Avon (DAV7), Cordeaux
(DCO1), Lake Burragorang 300 metres upstream from the dam wall (DWA2), Lake Yarrunga at
page 22
Bendeela Power Station (DTA8) and Lake Yarrunga Kangaroo River arm at Reed Island
(DTA10).
Frequent exceedances (50–75 per cent of observations) were seen at Lake Yarrunga near the dam
wall (DTA1), Lake Yarrunga Kangaroo River arm at Yarrunga Junction (DTA3), Prospect
Reservoir (RPR1 and RPR3), Lake Burragorang at Junction 14 kilometres upstream of the dam
wall (DWA9), Lake Burragorang Coxs River arm 24 kilometres upstream (DWA12) and Lake
Burragorang Wollondilly River arm at Tonalli (DWA39).
Very frequent exceedances (75–100 per cent of observations) were seen at Wingecarribee
Reservoir (DWI1), Fitzroy Falls Reservoir (DFF6), Lake Burragorang Coxs River arm 36 and 37
kilometres upstream (DWA19, DWA21) and Lake Burragorang Wollondilly River arm 23
kilometres upstream (DWA27).
Toxigenic cyanobacteria were identified at Fitzroy Falls Reservoir (DFF6), Lake Yarrunga
(DTA1, DTA8), Wingecarribee Reservoir (DWI1) and Prospect Reservoir (RPR1). Toxigenic
cyanobacteria were detected above guideline concentrations on a total of twelve occasions,
however the level of microcystin-LR toxicity was always within guideline levels.
In addition to the routine monitoring, 15 sites (7 additional) are monitored on a weekly basis from
October to May each year as part of a summer sampling program. This program may be extended
if measured levels exceed certain trigger levels.
page 23
8 References
SCA,2000. Operating Licence.
Supply Agreement.
page 24
Appendix A: Monitoring Site Codes
Table A 1
Water Quality Monitoring Report 2001–2002 – Appendix A
Catchment sampling locations and descriptions
Code
Description
E083
Coxs River at Kelpie Point
E130
Kowmung River at Cedar Ford
E157
Kedumba River at Maxwells Crossing
E206
Nattai River at The Crags
E210
Nattai River at Smallwoods Crossing
E243
Little River at fire road W4I
E332
Wingecarribee River at Berrima Weir
E409
Wollondilly River at Murrays Flat
E450
Wollondilly River at Golden Valley
E457
Mulwaree River at The Towers Weir
E488
Wollondilly River at Jooriland
E531
Werriberri Creek at Werombi
E601
Nepean River at Nepean Reservoir inflow
E602
Burke River at Nepean Reservoir inflow
E706
Kangaroo River at Hampden Bridge
E822
Mongarlowe River at Mongarlowe
E851
Shoalhaven River downstream of Tallowa Dam
E847
Shoalhaven River at Fossickers Flats
E860
Shoalhaven River at Mountview
E861
Shoalhaven River at Hillview
E890
Boro Creek at Marlowe
E891
Gillamatong Creek
G0515
Woronora River at The Needles
E8311
Corang River
Page A-1
Table A 2
Lakes sampling locations and descriptions
Code
Description
DFF6
Fitzroy Falls Reservoir – mid lake
DTA1
Lake Yarrunga near dam wall
DTA3
Lake Yarrunga Kangaroo arm Yarrunga Junction
DTA5
Lake Yarrunga Shoalhaven arm 7 km upstream
DTA8
Lake Yarrunga Bendeela Power Station
DTA10
Lake Yarrunga Kangaroo arm Reed Island
DWI1
Wingecarribee Reservoir at outlet
DWA2
Lake Burragorang 300 m upstream of dam wall
DWA9
Lake Burragorang at Junction 14 km upstream
DWA12
Lake Burragorang Coxs River arm 24 km upstream
DWA19
DWA21
DWA27
Lake Burragorang Wollondilly River arm 23 km upstream at Bimlow
DWA39
Lake Burragorang Wollondilly River arm at Tonalli
DCO1
Cordeaux Reservoir at wall
DCA1
Cataract Reservoir 30 m from dam wall
DGC1
Greaves Creek near dam wall
DLC1
Lower Cascade 25 m upstream
DAV7
Upper Avon at valve house
DNE2
Nepean Reservoir 200 m upstream
DTC1
Top Cascade 20 m upstream
DWO1
Woronora Reservoir near dam wall
RPR1
Prospect Reservoir at centre
RPR3
Prospect Reservoir near supernatant discharge point
Page A-2
Table A 3
WFP Inflow locations and descriptions
Code
Description
PWFP1
Inflow into Prospect WFP
HUC1
Inflow into Macarthur WFP
IWFPR
Inflow into Illawarra WFP
HWO1
Inflow into Woronora WFP
HBR1
Inflow into Orchard Hills WFP
HNE1
Inflow into Nepean WFP
HWA1
Inflow into Warragamba WFP
HCSR
Inflow into Cascade WFP
HGC01
Inflow into Greaves Creek WFP
HWI1
Inflow into Wingecarribee WFP
DBP1
Inflow into Kangaroo Valley WFP
Table A 4
Hawkesbury Nepean River – main stream locations and descriptions
Code
Description
N92
Maldon Weir upstream of Stonequarry Creek
N75
Sharpes Weir downstream of Matahil Creek, Camden STP
N67
Wallacia Bridge upstream of Warragamba River
N57
Penrith Weir upstream of Boundary Creek
N44
Yarramundi Bridge upstream of Grose River
N42
North Richmond upstream of North Richmond WTW
N35
Wilberforce upstream of Cattai Creek
N26
Sackville Ferry downstream of Currency Creek
N21
Lower Portland upstream of Colo River
N14
Wisemans Ferry downstream of car ferry
Page A-3
Appendix B: Plots of Monitoring Data
Water Quality Monitoring Report 2001–2002 – Appendix B
Figure B1 – Chloraphyll-a Concentrations
(All data as ug/L)
Page B-1
Figure B2 – Colour (All data as HU)
Page B-2
Figure B3 – Disolved Oxygen
(All data as % Saturation)
Page B-3
Figure B4 – Electrical Conductivity
(All data as mS/m)
Page B-4
Figure B5 – Filterable Aluminium
(All data as ug/L)
Page B-5
Figure B6 – Filterable Iron
(All data as ug/L)
Page B-6
Figure B7 – Filterable Manganese
(All data as ug/L)
Page B-7
Figure B8 – pH
Page B-8
Figure B9 – Suspended Solids
(All data as mg/L)
Page B-9
Figure B10 – Thermotolerant Coliforms
(All data as CFU/100ml)
Page B-10
Figure B11 – Total Aluminium
(All data as ug/L)
Page B-11
Figure B12 – Total Iron
(All data as ug/L)
Page B-12
Figure B13 – Total Manganese
(All data as ug/L)
Page B-13
Figure B14 – Total Nitrogen
(All data as mg/L)
Page B-14
Figure B15 – Total Phosphorus
(All data as mg/L)
Page B-15
Figure B16 – Turbidity
(All data as NTU)
Page B-16
Figure B17 – Other Variables for
Hawkesbury – Nepean Sites
Page B-17

2001-02 Annual Water Quality Monitoring Report

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