The Rivers and Creeks System
About 87% of rivers and creeks in the Port Phillip and Westernport region are natural. These rivers and creeks support native plants and animals and we need to understand them in order to protect their values.
How our rivers and creeks work
- When it rains, the water either runs across the land or soaks into the ground.
- The water that soaks into the ground is called ground water. It flows slowly through the soil and rocks into the base of rivers, providing them with a steady flow of water.
- The water that runs across the land is called surface water. It either flows directly into rivers, creeks or bays or collects in gutters or drains.
- The drainage system carries rainwater (surface water) from roofs, roads and buildings through gutters and drains, and discharges it into rivers and creeks where it eventually flows to the bays. This stormwater can carry pollutants which can affect the quality of water in our rivers and creeks.
- Wetlands help to control some of these water quality issues because they filter stormwater before it flows to rivers and creeks.
- Plants grow in and along the rivers and creeks, providing habitat for native animals and insects. They also stabilise the river bed and banks, preventing erosion and improving water quality by filtering the water.
Natural river flows
- A natural river flow (or an environmental flow) is the amount, timing and quality of water that flows in a river or creek.
- River flows can vary throughout the year due to the amount, quality and timing of rainfall and run-off.
- River plants and animals need different river flows during their life cycles to survive and reproduce.
The environmental water reserve
The environmental water reserve is the share of water in a river or creek that is set aside for the environment. This comes from water allocated specifically to ensure the river or creek remains healthy.
How can humans 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.
Protecting our environmental water reserve
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.
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. This work is carried out in consultation with the community and experts in the field.
Streamflow Management 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.