Water for the Environment
Environmental flows
An environmental flow (or a river flow) is the amount, timing and quality of water that flows in a river or creek.
These factors (volume, timing and quality of water) can all affect the health of a river or creek and how well it is able to provide for the animals and plants that rely on it.
Hoddles Creek in Launching Place
River plants and animals need different flows at different times of their life cycle to survive and reproduce. For example, high flows during spring can stimulate fish breeding, while groundwater can provide fish refuges during low flows over summer.
Environnmental Water Reserve
The environmental water reserve is the share of water in a river or creek that is set aside for the environment to ensure the river or creek remains healthy.
The Victorian Government has developed laws to make sure that a certain amount of water is legally reserved for the environment to protect the natural flow of our rivers.
Humans can affect natural river flows
The natural flow of a river or creek is affected when water is removed (diverted) for human use such as for irrigation, industry or domestic purposes.
In Victoria, there are guidelines on the amount of water that can be removed from rivers and creeks for human use.
The Victorian Government has also developed laws to make sure that a certain amount of water is legally reserved for the environment to protect the natural flow of our rivers.
How does the environmental water reserve work?
The environmental water reserve can be held in storage (in regulated rivers that have reservoirs), as run-of-river flows (in unregulated rivers that dont have reservoirs) or at groundwater level.
- Regulated environmental water reserve: In regulated rivers, the environmental water reserve is stored so that environmental flows can be controlled by releasing water from the storage reservoir.
- Unregulated environmental water reserve: In unregulated rivers it is necessary to protect minimum environmental flow levels by limiting or restricting harvesting at storage reservoirs and/or by restricting or banning licensed private diversions when river flows reach certain environmental flow trigger levels.
- The environmental water reserve for groundwater: is provided by capping the amount of water for extraction at or below a sustainable limit.
Protecting our environmental water reserve
Melbourne Water investigates the needs of particular rivers and creeks in the Port Phillip and Westernport region.
These studies allow us to work out the volume, timing and quality of water that is needed for a river or creek to stay healthy.
We also discuss with communities their water needs before setting guidelines on the amount of water that can be diverted for human use.
Current investigations
We are currently investigating the environmental water requirements of a number of rivers in our region.
These include eight rivers requiring streamflow management plans. These plans are developed to ensure the available water in a river or creek is shared in a sustainable way so all users, including the environment, receive the water they need.
More information:
Four rivers are also being investigated. They are the:
- Yarra
- Maribyrnong
- Werribee
- Tarago
This work is carried out in consultation with the community and experts in the field.
Flows at our estuaries
We are also doing flow requirement investigations for six estuaries in our region:
- Yarra
- Werribee
- Maribyrnong
- Bunyip
- Lang Lang
- Bass.