Richmond River
River Flow Objectives explained

This section explains each of the River Flow Objectives (RFOs). See the RFOs for each part of Richmond River catchment.

In total, there are twelve coastal 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 different parts of 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 meeting this objective, priority goes 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: all very low flows and most of the low flows; 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 water licences should not allow extraction during low flows.
• 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

• WSPs need to identify actions to achieve targets for each stream that balance local environmental, social and 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%.
• Augmentation of town water supplies to meet this objective will not be required. If augmentation is proposed for other reasons, appropriate levels of protection of low flows shall be determined on a case-by-case basis.
• Where extraction for stock 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, and 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 flow events are all important.

Measures to achieve objective

• Unless local information suggests appropriate alternative targets, the following limits on extraction are recommended for use:
• 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 environmental values during low flows. on the proportion of flows which 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 the limit may be 30%; for other streams it may be as high as 50%.)
• No increase in extractions from 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.
• Management plans 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 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 in reduced numbers of native fish-and in water quality problems.

In many coastal floodplain areas, drainage works or levees and reduced inundation cause gradual drying of potential acid sulfate soils and release of acid into waterways. They also have serious impacts on downstream ecosystems and fisheries.

Measures to achieve objective

• Management plans and actions for waterways need to include strategies to
• maintain, restore or mimic natural patterns of inundation, water movement and drying 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 environmental assessment.

Supporting information

• Property protection issues need to be taken into account.
• Restoring wetland inundation patterns will improve water quality and may reduce flooding problems in other parts of the floodplain.

	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, irrigation drainage or urban uses (e.g. garden-watering, effluent release) can sometimes make streams or wetlands 'wetter' than natural. In streams and wetlands that naturally dry out, this can create problems in maintaining habitat and vegetation, nutrient cycling, and signals for breeding. It can also lead to a high watertable 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 should be worked out on a case-by-case basis after giving due consideration to local views.

Supporting information

• This objective is being met in most of the streams in this catchment.

	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. 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 or development proposals with potential for flow variability problems, and take early action.

Supporting information

• Changes in variability are most likely to occur in controlled rivers but may occur in some locations or situations in other streams in this catchment.

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

Unnaturally fast changes in water level can occur in creeks with hard-surfaced catchments, such as urban areas, or in streams which receive large releases from dams or which have large pumping capacity relative to normal stream flow. 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. Very fast increases in flow and stream height can endanger people or aquatic organisms and contribute to bank erosion.

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 need for action.
• Rates of change are more likely to have increased in creeks below urban areas than in other streams of this catchment.

	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. In many coastal areas, lowering of groundwater may contribute to acid sulfate soil and water quality problems, or cause intrusion of seawater into aquifers and wetland soils that previously held fresh water.

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 whether impacts on these may be occurring due to changed recharge rates or excessive pumping.
• Identify longterm trends or changes in groundwater levels that are likely to threaten ecosystems or the quality of ground or surface-water.
• Determine appropriate action to keep groundwater level changes 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 restrict passage of plant propagules (e.g. seeds) and animals. This can be a major problem for species which depend on upstream and downstream migration during at particular times in their lifecycle.

Measures to achieve objective

• Implement the NSW Weirs Policy (DLWC 1997b).
• Identify and take action to reduce the impacts on fish, other animals, plants and water quality of other structures that impede the two-way movement of water in streams-e.g. floodgates, tidal barriers, culverts.

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 dams or large weirs.

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

Unforeseen or irregular events occur in river systems at various times, 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. Release of some of the water in a dam for the downstream environment might be appropriate in particular circumstances. WSPs should identify potential situations when such action may be warranted and any necessary associated procedures.

Supporting information

• WSPs need to consider this objective only in relation to streams with significant water extraction or dams from which releases can be made.

	Maintain or rehabilitate estuarine processes and habitats
	Maintain or rehabilitate estuarine processes and habitats

Coastal lagoons, estuaries and river mouths often naturally change in response to storms or tides. Flood mitigation structures, weirs and other works also affect estuaries by limiting tidal flow, changing salinity conditions or altering water levels. Development of estuarine areas can also lead to disturbance of acid sulfate soil deposits, which may release large amounts of sulfuric acid and toxic metals into the estuarine environment.

Upstream management of rivers also affects estuaries and lagoons. Stormwater carries nutrients, organic matter and sediments. Scouring as a result of flooding can affect the opening and closing of river mouths. Reduced freshes and flooding in estuaries severely depletes food sources for estuarine species. This can contribute to the decline in the number and abundance of species which use estuaries as either habitat or nursery grounds.

Measures to achieve objective

• Dredging beyond minimal maintenance dredging for navigation requires environmental assessment.
• Draining or disturbance of areas of potential acid sulfate soils must be minimised.
• Tidal wetlands should continue to receive tidal flushing .
• Minimise impact of flood levees and gates, roads and other barriers (see also RFO Maintain wetland and floodplain inundation).
• Water-based activities should minimise impact on fish habitat.
• Other processes affecting or potentially affecting estuary health should be addressed (e.g. where increased urbanisation is proposed), ensuring that impacts are avoided or minimised.

Supporting information

• Dredging or drainage could expose acid sulfate soils. Treatment of acid sulfate soils is expensive and relatively untested, the priority is to minimise exposure of these soils.
• Fish habitats, such as protected areas, seagrass beds and mangroves, should be protected from pollution and increased sedimentation or erosion. Polluted sites should be rehabilitated.

This page was published 1 May 2006