River flows and water supply

The health and values of the Yarra are closely linked to its water flows – both the quantity and the variability/pattern of flows. Many aspects of native plants’ and animals’ lives are dependent on different flow levels and flow “events”. Examples include:

• A short period of high flows to trigger Macquarie Perch spawning,
• inundation of a wetlands for nesting waterfowl,
• alternating high and low water levels as needed by River Red Gums.

But the capture and extraction of the Yarra’s water to supply residences, factories and farms in the Greater Melbourne area has significantly altered both the quantity and pattern of river flows.

The program to release environmental flows down the Yarra which commenced in September 2011 is helping restore some of the natural flow pattern; but not all of the natural flows (e.g. inundation of floodplains) can be so restored.

Currently, no effort is being made to restore the natural quantity/level of flows, or size of the river. The river’s size governs the abundance of species, and has social values, being a factor in the river’s heritage, and water based recreation such as paddling. (NB We are not advocating big floods that would damage property or assets above the natural floodplain.)

We believe that:

• To restore near-natural flow rates, the amount of water extracted needs to be reduced by
  • measures to lower total water consumption and
  • policies and major investment in alternative sources, such as recycled “waste” water and stormwater;
• To ensure a healthy flow pattern, the environmental flows program needs a greater water allocation and more security (e.g. government guarantee) during times of water scarcity.