VEWH - What is water for the environment?

Water planned and delivered to benefit the environment

Water used to improve or maintain the health of rivers and wetlands

Water held in entitlements for the environment

What is water for the environment?

An environmental entitlement – ‘water for the environment’ - is a legal right to water available in a storage, river system or specified place under rules and conditions, like other water entitlements held by other water users.

It is water allocated and managed specifically to improve the health of rivers, creeks, wetlands and floodplains. Healthy waterways are vital for the people, plants and animals that depend on them, now and into the future.

Environmental water managers plan to deliver water held for the environment to support plant and animal populations, improve water quality and build species resilience while the climate changes.

Over the past 100 years or so, most of Victoria’s major rivers have been dammed with up to half their natural flows held in storages to supply households, farms, cities and industries and provide security for dry times.

Water for the environment aims to replace some of the essential flows rivers had before they were regulated with dams, weirs and channels. The water is released when rivers and wetlands need it most to counter the impacts of reduced natural flows.

Stimulates animals like native fish to feed and breed (for example, cod and yellowbelly fish need to be able to move on to floodplains to feed)

Triggers plants to seed or germinate (for example, river red gums need flooding for seeds to germinate)

Moves carbon between rivers, floodplains and estuaries, an important process for food chains

Allows fish and plants to move about rivers and colonise new areas

Helps restore groundwater

Stabilises river banks through better plant growth, reducing erosion into the river

Flushes out salt along river banks and floodplains

Changing flows

Instead of flowing naturally, with high flows in winter and low flows in the hotter months of summer, rivers now run higher when water needs to be delivered for farming and urban use. These changes have interrupted many of the natural river and wetland processes needed by native plants and animals to survive, feed and breed.

Water for the environment is released into some of these rivers and wetlands to improve their health and protect environmental values.

In rivers, water for the environment can be delivered to mimic some of the flows that would have occurred naturally before rivers were modified.

Water for the environment does not try to return rivers and wetlands to their pre-European condition. Many rivers and wetlands are so modified that this is not feasible; however environmental watering can help to minimise some of the impacts of these modifications on rivers and wetlands.

Managers of water for the environment generally focus on returning some of the small and medium-sized river flows important in the life cycles of native plants and animals.

In wetlands, water for the environment is focused on mimicking some of the natural wetting and drying cycles which plants and animals depend on for their diversity and long-term resilience.

Types of flows

It's not simply the amount of water flowing in a river that's important.

It's the entire environmental flow regime that matters, including the volume, timing, duration, frequency and quality of flows that are provided. Like the natural flow of rivers, different combinations of these provide a range of benefits for ecosystems.

Releasing small amounts of water, called 'freshes', through summer helps to maintain or improve water quality. Flooding in spring replenishes a river channel and provides soil and nutrients for floodplains, as well as being vital for waterbirds and native fish to breed.

Types of flows

Flows are characterised by their size, frequency, timing and duration.

Type of flow	Description	Benefits
Cease to flow	No discernible flow in a river.Total or partial drying of the river channel.	Drying is important for some ecological processes. It can also reduce exotic pests such as European carp.
Low flows, also called base flows	Low flows generally provide a continuous flow through the channel. This may maintain the flow above a cease to flow, or provide habitat as a change from high flows.	Connects in-stream habitats and can benefit other river users, such as providing water for livestock.
Freshes	Small pulses of water. These flows exceed the low flow and last for at least several days. Freshes are a key contributor to the variability of flows.	Helps maintain or improve water quality and prevents algal blooms.
High flows	Persistent increases in the seasonal base flows that remain within the channel. High flows do not fill the channel to 'bankfull'.	Allows for fish migration and enhances recreational fishing opportunities.
Bankfull flows	Flows that reach the top of the river bank with little flow spilling onto the floodplain.	An important trigger for fish breeding. Helps move sediment and maintain banks.
Overbank flows	Flows greater than bankfull, inundating adjacent floodplains. Environmental water is not released for overbank flows on private land without permission from landholders.	Maintains floodplain and wetland connectivity, stimulates fish and bird breeding and enhances recreational opportunities Overbank flows are critical for a range of ecological factors, including floodplain productivity.

A typical natural flow pattern of a victorian river, before the construction of dams, weirs and channels — Modified from a graphic that originally featured in Why rivers need water, Department of Sustainability and Environment 2007

Page last updated: 12/12/19