Environmental flows

An environmental flow is when water is released from a dam or weir to maintain downstream river health, and the health of the environment.

Environmental releases form part of each water source's water sharing plan (WSP). A WSP is a NSW law that sets out how water in the system is to be shared, used, managed and traded. These environmental releases are designed to mimic the flow patterns of a river by passing a portion of inflows from the dam, downstream.

Environmental releases can also occur when water is ordered from an environmental water holder. Both the NSW and Commonwealth Governments hold these licences. While the rules are the same as other licences, water is simply released from a storage but not extracted, allowing it to flow through the system.

There are a number of benefits to environmental flows. Environmental flows can help to:

• protect aquatic ecosystems and reduce aquatic weeds and frequency of algal blooms
• maintain river health
• improve conditions for native fish, frogs, water birds and river-dependent plants and animals that rely on different flows to trigger migration and breeding
• protect river condition for recreation such as boating and swimming

We publish data on environmental flows on WaterInsights for each water source, under the allocation tab.