Barwon-Darling and Far Western
Water Quality and River Flow Objectives
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At a Glance |
This section gives the Water Quality Objectives (WQOs) and the River Flow Objectives (RFOs) for the Barwon-Darling and Far Western catchments, which should be used to develop plans and actions affecting water quality and river health. Only the priority RFOs are listed in this section, but the remaining objectives still need to be considered when developing flow management plans or dealing with particular local river conditions.
Town water supply subcatchments
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The streams in town water supply subcatchments typically feed into a town's water supply storage.
Map: This category applies to streams running through areas coloured light blue on the map.
Water Quality Objectives
Protection of:
River Flow Objectives
All eleven inland RFOs apply, but no new priority action is required to meet these objectives.
Supporting information
- Includes Umberumberka Reservoir and Stephens Creek Dam. These storages supply much of Broken Hill's water needs.
- The Stephens Creek and Umberumberka reservoirs are important water supplies except in droughts, when they dry up. Water then has to be pumped at great expense from the Menindee Lakes, more than 100 kilometres away. Local studies indicate that there has been an increase in erosion in the catchments since European settlement in Broken Hill. This affects water quality, is silting up the reservoirs, and is increasing the frequency of expensive pumping from Menindee.
- Continued protection of low and high flows is particularly important for maintaining the security of the town water supply.
- Other dedicated town water supply areas in the far western catchments may be defined in future.
Mainly forested areas
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The community values streams in national parks and state forests for conservation or recreation. This may apply to other areas of high conservation value if any are defined locally.
Map: Applies to streams running through areas coloured green on the map. Also applies to other forested areas, if any are defined locally.
Water Quality Objectives
Protection of:
River Flow Objectives
All eleven inland RFOs apply, but no new priority action is required to meet these objectives.
Supporting information
- Where the whole catchment of a stream has a near-natural vegetation cover and little soil erosion, WQOs and RFOs are generally, though not always, achieved. High-level protection should be given to flows and water quality in these least-affected streams and other streams with high conservation values. Existing management practices in national parks or other reserves may already aim to achieve this. In some streams, local circumstances may restrict achievement of objectives, such as where animal faecal contamination reduces suitability of water quality for swimming.
- Watercourses flowing from areas with unnaturally high rates of soil erosion have increased turbidity and sedimentation, reducing the natural and human use values of the water and downstream environment; for example, by filling wetlands and affecting stock water supplies.
- Trees and other native vegetation on streambanks and in floodplains can provide good habitats for native fish, other animals and plants. The effective value of these habitats is likely to be limited if the water quality is inadequate or if flow patterns are not sufficiently close to natural to provide correct cues for breeding and to enable the survival of offspring. Keeping water quality and flow patterns as close as possible to natural is therefore desirable.
- If the catchment or river management committee considers that there are high-conservation-value streams outside reserves, to which a high level of protection should apply, they may seek local views and make recommendations to the Government.
Waterways affected by urban development
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Waterways within urban areas are often substantially modified and generally carry poor-quality stormwater. Local communities are often keen to see these waterways returned to more natural conditions.
Map: These areas are shown in orange or as orange dots on the map.
Water Quality Objectives
Protection of:
River Flow Objectives
Supporting information
- This category includes waterways within Brewarrina, Bourke, Wilcannia and Menindee.
- In some urban waterways, aquatic ecosystems are considerably modified. A return to pristine aquatic ecosystems in these areas is unlikely and impractical, but water quality conditions for existing ecosystems can be improved greatly for the benefit of local species and broader catchment health. Data from other local aquatic ecosystems of similar type, in areas that are not urbanised, may provide achievable criteria for these modified aquatic ecosystems.
- Action is needed to reduce or avoid effects on surface and groundwater quality from stormwater, sewage discharges and unsewered villages.
- Local councils have produced stormwater management plans for towns with populations above 1000 people.
- The Department of Energy, Utilities and Sustainability's (DEUS) Best-practice management of water supply and sewerage guidelines (DEUS 2004) helps councils provide integrated water cycle management in a way that will achieve sustainable outcomes.
- The tendency for urban development to cause rapid rises in stormwater runoff should be minimised by applying guidelines for water-sensitive urban design.
Uncontrolled streams
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These are all streams and waters that are not in the other categories.
Map: Uncontrolled streams are shown as blue lines on the map.
Water Quality Objectives
Protection of:
River Flow Objectives
In the Warrego and Moonie rivers, which have a few active water diversion licences, all eleven RFOs apply. Some priority action may be warranted to achieve the following objectives:
In other streams, all eleven RFOs apply, but most are currently being met. Maintenance of the relatively natural flow regimes in these streams is important.
Supporting information
- This category includes the Bulloo, Paroo, Warrego and Moonie river systems; Yanda, Mulga and Sandy creeks south of the Darling; and numerous ephemeral streams, lakes and wetlands that do not drain into any river. Almost all of these streams have near-natural flow patterns.
- Rangelands cover a large area of NSW and have complex issues associated with their use and a great diversity in waterbody types and influences on them.
- The environmental objectives apply to uncontrolled streams wholly within NSW. For the streams crossing the NSW-Queensland border, achievement of environmental objectives will depend on interstate consultations regarding flow and water quality management, and on resource management decisions made within Queensland. The Queensland Government has established Water Resource Plans for these streams.
- The main environmental values to protect with appropriate water quality in the rangeland areas are aquatic ecosystems (providing for their ephemeral or intermittent nature); stock water and irrigation (Moonie and Warrego rivers only); and drinking water (mainly groundwater). Most human activities in large parts of the far western catchments depend on groundwater. In many cases it is taken from the Great Artesian Basin, which is too deep to interact with rivers or ecosystems except in a few locations, such as Peri Lake.
- Eroded soil and chemical contaminants reaching waterways need to be reduced.
- Where surface waters or groundwaters are used to supplement drinking water from rainwater tanks, the source water should be maintained at high enough quality for available or affordable treatment to be effective in the long term.
- A number of streams in the far west have been identified by local people or by scientists as having high natural values; for example, the Paroo river and wetland system, Caryapundy Swamp, Cuttaburra Basin and channel system, and various salt lakes. These values depend in part on maintenance of water quality and near-natural flows from the catchment, and on management that avoids significant changes to flow distribution or barriers to fish movement. In this relatively flat country even low structures, such as weirs for stock and domestic needs, can affect flow patterns, geomorphic processes, instream habitat and fish passage.
- The Paroo-Cuttaburra has complex flow patterns and water moves down a series of channels into swamps and lakes. It is important to maintain the Paroo's current water quality and flow regime in its mostly healthy state. It also has great value as a reference point for comparison with catchments with altered or near-natural flow patterns.
- There are many lakes distributed widely through far western catchments. They are diverse in their characteristics. Many are usually dry, while others fill more often in response to flooding or local rainfall and then dry out. The salinity of water flowing into each lake and the salinity levels reached before a lake dries out also differ between lakes. Ecological values in some lakes are closely associated with natural changes between fresh and brackish water. High erosion rates may be reducing the value of some lakes. Fertile soils and periodic supplies of water have attracted a range of uses of these lakes, including opportunistic cropping. A number of lakes have altered water regimes to provide permanent water supplies. (See Wetlands and Waterbirds in Northwestern New South Wales, 1994, NSW National Parks and Wildlife Service).
- The Queensland Government has established Water Resource Plans for the Queensland parts of the Moonie, Warrego Paroo and Condamine-Balonne Rivers. The NSW Government will continue to discuss with the Queensland Government the management of these and other streams that cross into NSW.
- The Queensland and NSW Governments signed the Paroo River Agreement in 2003. The agreement effectively prevents any dams or river diversions, to protect this river as the last free-flowing river in the Murray-Darling Basin.
Controlled rivers with reduced flow
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These extend from Mungindi to the top of Lake Wetherell and include anabranches and wetland systems on the floodplain. Almost all flows are from tributaries in other regions of NSW or Queensland. Dams and diversions in those regions reduce inflows to the Barwon-Darling. Flow patterns are also affected by pumping, weirs and natural processes along the Barwon-Darling.
Map: Controlled rivers are marked on the map in red lines; the floodplain is coloured brown on the map.
Water Quality Objectives
Protection of:
River Flow Objectives
No interim RFOs were recommended for the Barwon-Darling in 1999. Environmental flow rules recommended by the Barwon-Darling River Management Committee were adopted. These rules were implemented by the then DLWC in late 2000, following the construction of 5 new flow gauging stations at strategic locations along the river. The RMC was discontinued in 2003, following submission of its final advice to the Minister for Natural Resources on a Cap Management Strategy. During 2006/2007 the Department of Natural Resources (DNR) will be developing a Water Sharing Plan (WSP). Community engagement in the preparation of the WSP will be facilitated by the Western Catchment Management Authority (CMA).
Supporting information
- Water quality in the Barwon-Darling depends on the relative contributions of its major tributaries as well as activities along the floodplain.
- The Darling often carries water with naturally high turbidity and nutrient levels (e.g. phosphorus). However, turbidity or nutrient levels are increased above their natural levels as a result of erosion or development in upstream catchments. Key actions to limit turbidity and nutrient levels include reducing discharge of nutrients from sewage treatment plants and further reducing soil erosion, preventing chemically polluted runoff from entering streams, and limiting pathways for nutrient-rich animal faeces to reach streams.
- Flows from the western side of the basin have the highest turbidity levels (Warrego and Culgoa) and generally remain turbid as they pass down the Barwon-Darling. Flows from the eastern catchments - for example, Gwydir and Namoi - tend to become clear more rapidly than the western river sources when conditions are suitable; for example, with declining flow rates. Rivers from the south-east catchments (Castlereagh, Namoi, Macquarie and Bogan) have the highest salinities, and the Macintyre, Namoi, and Gwydir appear to have the highest phosphorus concentrations.
- The Riverwatch program provides detailed information on water quality and flow interactions. Reports have shown that the part of the river between Bourke and Tilpa appears to be the most algae-prone, possibly due to its five weir pools, lower flows and saline groundwater inflows, high phosphorus and lower turbidity levels. Riverwatch is improving the understanding of the relationship between flow, turbidity, salinity and algae. New monitoring programs and an information strategy are currently under way.
- DNR's Integrated Monitoring of Environmental Flows Project incorporates aspects of water quality and river health that can be improved with flow management. Management of low to moderate flows can, for example, aim to achieve lower levels of salinity below the locations where saline intrusion occurs during periods of very low flow. Alternatively, it could aim for higher levels of dissolved oxygen in pools by protecting rises that are sufficiently fast-flowing to disturb the water in the bottom of pools and replace it with oxygen-rich water from the surface. The risk of high nutrient loads and turbidity levels being exacerbated by bank slumping and erosion may also be limited by managing extraction from moderate to low flows in the tail of rapidly falling flows.
- Saline groundwater seepage can significantly affect water quality, particularly when surface flows are lower or reduced. For example, a major saline seepage starts 50 metres downstream of Weir 19a (near Bourke) and can be at salinities similar to that of sea water. This seepage increases salinity and tends to reduce turbidity and phosphorus concentrations in low flow conditions through its effect on settling out sediments in the water column. With clearer water, sunlight penetration is greater and increases the incidence of algal blooms.
- The Darling below Louth forms into long stretches of warm shallow pools for long periods, which affects water quality. The period of this poorer water quality may be reduced by the implementation of the Barwon-Darling and Namoi flow rules, bringing benefits to both water users and ecosystems in the Darling.
- Freshwater foods (such as mussels) are currently taken and eaten raw from various locations. NSW Health recommends against the consumption of raw shellfish harvested on a non-commercial basis and local communities should be made aware of the risks involved.
- Waters of the Poopelloe-Talyawalka lake systems are not used for irrigation or drinking water, but people may sometimes consume fish or freshwater mussels from them.
- Surveys indicate that most people in other parts of NSW are prepared to pay for improved water quality in the Darling (see Water Quality Improvement in the Darling River: A Contingent Valuation Study, 1994, NSW Department of Water Resources). Community discussion meetings in 1998 confirmed that people living near the Darling value protection and improvement in the river's water quality.
- Collarenebri, Wilcannia, Brewarrina and Bourke require town water supplies of a quality high enough for clarification and disinfection to be effective.
- Some communities and homesteads depend on bores that tap shallow groundwaters associated with the floodplain and nearby river. Others depend on deeper groundwater.
Controlled rivers with reduced flow (Culgoa, Birrie, Bokhara and Narran rivers)
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Most flow comes from the Condamine-Balonne River. In most seasons, flow is reduced by upstream diversions for irrigation in Queensland. Low flows are controlled by releases from Jack Taylor Weir in Queensland.
Map: These rivers are shown as red lines within a pink area on the map.
Water Quality Objectives
Protection of:
River Flow Objectives
Queensland has established Water Resource Plans for the Condamine, Balonne, Culgoa and Narran rivers. The NSW Government has not recommended RFOs or priorities for action for these rivers, but development of Water Sharing Plans for the NSW portion of these rivers should consider all inland River Flow Objectives to the maximum extent possible.
Supporting information
- The achievement of WQOs will be affected by river flows from Queensland. The quality of water leaving the NSW parts of these streams should also enable achievement of objectives for the Darling, including irrigation water supplies.
- Freshwater foods (such as mussels) are currently taken and eaten raw from some waters. NSW Health recommends against the consumption of raw shellfish harvested on a non-commercial basis and local communities should be made aware of the risks involved.
Regulated rivers (lower Darling, Great Anabranch and lakes, and lower Murray river system)
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These are regulated streams supplied with water from the Menindee Lakes System or Lake Hume. The management of Menindee Lakes, regulation of flows, and management of extraction and water quality are affected by agreements to meet water needs in South Australia as well as local needs.
Map: These rivers are shown as yellow lines within a pink area on the map.
Water Quality and River Flow Objectives
A separate interstate process, chaired by the Murray-Darling Basin Commission and involving the NSW, Victorian and South Australian Governments, is being used to set objectives for both water quality and flow in the Murray and the lower Darling river systems. The MDBMC has approved provisional Water Quality Objectives for the Darling River between Menindee and Wentworth - download the Draft Provisional Water Quality Objectives - DraftMDBMCWQOs.pdf (pdf 63kb)
This page was published 1 May 2006
About the Objectives
