NSW Water Quality and River Flow Objectives About the Objectives Department of Environment, Climate Change and Water   Select from the scrolling list, statewide map or catchment list Select a catchment Barwon-Darling and Far Western Bega River Bellinger River Border Rivers Brunswick River Camden Haven and Hastings River Castlereagh River Clarence River Clyde River and Jervis Bay Cooks River Georges River Gosford and Northern Beaches Lagoons Gwydir River Hacking River Hawkesbury-Nepean River Hunter River Karuah River and Great Lakes Lachlan River Illawarra Lake Macquarie and Tuggerah Lakes Macleay River Macquarie-Bogan River Manning River Moruya River Murray River Murrumbidgee River and Lake George Nambucca River Namoi River Richmond River Shoalhaven River Sydney Harbour and Parramatta River Towamba and Genoa River Tuross River Tweed River Williams River

Castlereagh River
River Flow Objectives explained

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• Recommending variations to objectives
• Protect pools in dry times
• Protect natural low flows
• Protect important rises in water levels
• Maintain wetland and floodplain inundation
• Mimic natural drying in temporary waterways
• Maintain natural flow variability
• Maintain natural rates of change in water levels
• Manage groundwater for ecosystems
• Minimise effects of weirs and other structures
• Minimise effects of dams on water quality
• Make water available for unforeseen events

This section explains each of the River Flow Objectives (RFOs). See the RFOs recommended for specific parts of the Castlereagh River catchment.

In total, there are eleven interim inland River Flow Objectives, each dealing with a critical element of natural river flows.

Flow patterns in many rivers have been significantly altered and will not return to natural flow regimes. The NSW Government is not attempting to restore completely natural flow patterns where the community significantly benefits from altered flow patterns. Communities and the Government have identified important areas where we can make adjustments to maintain or improve river health while continuing to benefit from water use.

Water Sharing Plans (WSPs) where developed, will contain integrated actions and timeframes to achieve objectives and implement identified actions in consultation with the community. Different approaches and outcomes will apply across the catchment.

Recommending variations to objectives

The Natural Resources Commission (NRC) will review the role of WSPs in achieving state-wide natural resource management standards and targets after 5 years of the plan being made. As part of this review the NRC will call for public submissions and consider other state-wide policies or agreements that are relevant to the catchment management area. The Minister for Natural Resources will consider the review undertaken by the NRC when deciding whether to extend the duration of the current water sharing plan or to make a replacement plan.

The Minister may also amend plan actions at any time if the plan so allows or if it is deemed to be in the public interest to do so

	Protect pools in dry times
	Protect natural water levels in pools of creeks and rivers and wetlands during periods of no flows

During dry times, some streams stop flowing and form pools. Pools and wetlands are refuges for aquatic plants and animals. Pumping water from these areas can make it more difficult for many species to recover after a drought.

Measures to achieve objective

• There should be no water extraction from streams or wetlands in periods of no flow.
• If conditions on water licences do not provide for this objective to be met, priority should be given to implementing it by actions appropriate to local circumstances.

Supporting information

• Along with social and economic considerations, WSPs should define when and how to protect specific pools:
• in natural wetlands with licensed pumps
• in streams where flow occurs under the surface
• where these pools have become deeper or shallower.
• Where water extraction for stock and domestic use is high (e.g. in rural subdivisions surrounding large urban centres), the NSW Government may recommend actions to protect the environment in periods of no flow.

	Protect natural low flows
	Protect natural low flows

Water extraction and storage are high in dry times and impose long artificial droughts that increase the stress on aquatic plants and animals.

Measures to achieve objective

• Share low flows between the environment and water users and fully protect all very low natural flows.
• Very low flows: flows below the level naturally exceeded on 95% of all days with flow.
• Low flows: flows below the level naturally exceeded on 80% of all days with flow.
• Unless environmental, social and economic evaluations give an appropriate alternative, the following limits on water extraction apply:
• Environmental share in high-conservation-value streams: to be all very low flows and most of the low flows. There should be no increase in extraction of low flows.
• Environmental share in other streams: all very low flows and 50-70% of daily low levels.
• New or transferred licences should not allow extraction during low flows below the 80th percentile.
• In streams with little water use or important conservation values, minimise risks to ecosystems during low flows.
• Review management of town water supplies to assess whether changes may help achieve the objective without significantly affecting reliability.

Supporting information

• Water Sharing Plans (WSPs) need to identify actions to achieve targets for each stream that balance local environmental, social or economic considerations.
• In streams where extraction currently exceeds 50% of low flow, WSPs may include provision to achieve targets. Where extraction is currently below 30% of low flow, it should not be allowed to exceed 30%.
• Town water supplies will not need to be augmented to meet this objective. If augmentation for other reasons is proposed, appropriate levels of protection of low flows will be determined on a case-by-case basis.
• Where extraction for livestock and domestic use is high (e.g. in rural subdivisions), WSPs may recommend appropriate actions to protect environmental values during low flows.

	Protect important rises in water levels
	Protect or restore a proportion of moderate flows ('freshes') and high flows

Rain causes peaks in river flows. This 'pulsing' of flows, including their duration, may trigger migration of animals and reproduction of plants and animals; provide over-bank flows to wetlands and floodplains; shape the river channel; and control water quality and nutrients. Water storage and extraction can alter or remove freshes, inhibiting these vital processes. The height, duration, season and frequency of higher flows are all important.

Measures to achieve objective

• Unless local information shows appropriate alternative targets, the following limits on extraction are recommended for use by RMCs:
• No extraction of more than 30-50% of moderate to high flows on a daily basis. (This means that, for each stream, the WSP may recommend an appropriate limit on the proportion of flows that may be extracted whenever flows are greater than the level that would naturally be exceeded on 80% of all days with flow. For some streams this limit may be 30%; for other streams it may be as high as 50%.)
• No increase in extractions in high-conservation streams.
• Where use exceeds the above limit, appropriate ways of limiting the volume or controlling the timing of extraction are needed.

Supporting information

• These targets are currently being met in many streams, particularly those with low water extraction.
• WSPs need to include appropriate actions to achieve this objective that balance environmental, economic or social considerations.

	Maintain wetland and floodplain inundation
	Maintain or restore the natural inundation patterns and distribution of floodwaters supporting natural wetland and floodplain ecosystems

Floodplain and wetland ecosystems develop in response to flow patterns and the nature of the landscape between the river and wetlands or floodplains. Floodplain works can change the flooding patterns, which will lead to changes in habitat and vegetation. These changes can be expected to result in reduced or different species diversity and abundance, particularly reduced numbers of native fish, and water quality problems.

Measures to achieve objective

• WSPs and actions need to include strategies to:
• maintain, restore or mimic natural inundation and drying patterns in natural and semi-natural wetlands and remaining native floodplain ecosystems
• ensure adequate access for native fish to and from floodplain wetlands.
• Flooding patterns should not be altered without proper environment assessment.

Supporting information

• Property protection issues need to be taken into account.

	Mimic natural drying in temporary waterways
	Mimic the natural frequency, duration and seasonal nature of drying periods in naturally temporary waterways

Continuous or seasonal water releases from water storages can mean streams and wetlands can sometimes be 'wetter' than natural. In streams and wetlands that naturally dry out, this can create problems in maintaining habitat, vegetation, nutrient cycling and signals for breeding. It can also lead to a high water table and associated salinity problems. Natural wetting and drying cycles produce diversity of habitat and, therefore, high species diversity.

Measures to achieve objective

• Identify any unregulated streams where unnatural flows have greatly reduced drying periods. Assess potential short- and long-term environmental, economic and social effects of this change and of possible management alternatives.
• Decide what, if any, action is appropriate to implement this objective in streams and wetlands on a case-by-case basis after giving due consideration to local views. Where relevant, agreements under land and water management plans should be respected, but this objective should be taken into account, along with WQOs, social objectives and economic objectives, in resolving outstanding or new management issues for drainage water.

Supporting information

• This objective is being met in most streams.
• Continuous or seasonal water releases include irrigation drainage and sewage treatment plant effluent.

	Maintain natural flow variability
	Maintain or mimic natural flow variability in all streams

Australia's rainfall and river flows are naturally variable. The way we currently store and divert river water can reduce natural pulsing of water down rivers and maintain artificially high or stable river heights. Hydro-electric releases can vary unnaturally between day and night. In urban areas and other places where the ability of the land to absorb or detain rainfall is reduced, more water runs off rapidly, so water levels will rise higher. These changes often create problems with streambank stability, biodiversity and signals for breeding and migration.

Measures to achieve objective

• Identify streams with unnatural flow variability and develop actions to mimic natural variability.
• Identify streams with potential for flow variability problems and take early action.

Supporting information

• This objective applies mainly to controlled rivers but may apply in some locations or situations in uncontrolled streams.
• This objective may also affect the achievement of Water Quality Objectives.

	Maintain natural rates of change in water levels
	Maintain rates of rise and fall of river heights within natural bounds

Shutting off dam releases, or starting many pumps together, can drop river levels too quickly. If water levels fall too fast, water does not drain properly from riverbanks and they may collapse. Migration of aquatic animals may also be restricted by such sudden falls in river height.

Measures to achieve objective

• Identify locations where water levels often rise or fall faster than they would naturally. Identify the reasons and impacts. Remedial action requires case-by-case assessment.
• Identify potential problems and take early action.

Supporting information

• Local observations, such as bank erosion, may indicate a need for action.
• Solutions may involve slight changes to the operation of larger pumps or diversion works.
• This objective does not usually apply to uncontrolled streams.

	Manage groundwater for ecosystems
	Maintain groundwater within natural levels and variability, critical to surface flows and ecosystems

Some shallow groundwaters are directly linked to flows in streams and wetlands. They may provide base flows in rivers during dry periods and may be primary sources of water for wetland, floodplain and riparian vegetation. Seriously depleting groundwater in dry times may lead to unnatural recharge of groundwater from surface waters during the next flow.

Measures to achieve objective

• Implement the State Groundwater Policy (DLWC 1997a, 1998b).
• Identify any streams or ecosystems that may depend on high groundwater levels and assess impacts of reduced recharge or excessive pumping.
• Identify where groundwaters may be rising and likely to threaten ecosystems or surface water quality.
• Determine appropriate action to keep groundwater levels within acceptable bounds.

Supporting information

• WSPs should identify areas and actions needed, particularly where there are threatened ecosystems.

	Minimise effects of weirs and other structures
	Minimise the impact of instream structures

Most instream structures (e.g. weirs) convert flowing water to still water, thus altering habitat and increasing the risk of algal blooms or other water quality problems. Barriers prevent passage of plant propagules (e.g. seeds) and animals.

Measures to achieve objective

• Implement the NSW Weirs Policy (DLWC 1997b).
• Identify and take action to improve fish passage on other structures that impede the two-way movement of native fish along streams or natural high-flow channels.

Supporting information

• The NSW Weirs Policy (DLWC 1997b) and weir review process helps set priorities and assess management options.

	Minimise effects of dams on water quality
	Minimise downstream water quality impacts of storage releases

Many dams release water from the bottom of reservoirs where temperatures and dissolved oxygen are low and nutrient concentrations are high. These changed water quality conditions can affect the river downstream for hundreds of kilometres. For instance, many native fish will not breed in colder water.

Measures to achieve objective

• Determine whether water quality from dam releases limits achieving WQOs in unregulated streams and develop appropriate actions.

Supporting information

• WSPs need to consider this objective only in relation to those streams with large weirs or dams.

	Make water available for unforeseen events
	Ensure river flow management provides for contingencies

River systems can sometimes be affected by unforeseen or irregular events-such as algal blooms or the start of bird-breeding seasons. As river flows are a major determinant of many of these processes, we can sometimes alleviate a water-quality or environmental problem by better managing river flows.

Measures to achieve objective

• Current water licence conditions enable pumping to be suspended in the rare event that this may be necessary. WSPs should identify potential situations when action may be warranted and the steps that should be taken to manage flows at these times.

This page was published 1 May 2006