The wettest July for the Wimmera in more than a decade has soaked the thirsty region - creeks and rivers are flowing, lakes and wetlands are filling, frogs are croaking, and birdlife is abundant.

Over the past few weeks, all eyes have been on natural flows in the Wimmera River as they passed through Horsham, Dimboola and Jeparit into Lake Hindmarsh, improving water quality and delivering optimism for the summer ahead.

The photo featured at the top of the update shows the Wimmera River flowing through the Jeparit Weir on 3rd August 2021, taken by Fay Gordes.

A text-copy of the update is available below the image for easy reading.

The wettest July for the Wimmera in more than a decade has soaked the thirsty region - creeks and rivers are flowing, lakes and wetlands are filling, frogs are croaking, and birdlife is abundant. Over the past few weeks, all eyes have been on natural flows in the Wimmera River as they passed through Horsham, Dimboola and Jeparit into Lake Hindmarsh, improving water quality and delivering optimism for the summer ahead.

Q&A

Is this natural flow improving water quality?

High flows pick up sediments from eroding gullies, dirt roads and are earth, making the river look murkier than usual. Water quality is much improved though; salinity levels dropped by over 10,000 µS/cm at Tarranyurk when the flow front arrived. A month earlier salinity levels were almost a third of seawater.

What’s the difference between environmental and natural flows?

Natural flows are generated by runoff in the catchment during wet weather. Some of this water can be harvested into storages like Taylors Lake, subject to rules which determine how much can be taken. But water cannot flow into storages at higher elevations than where it is diverted from a waterway. For example, Wimmera River flows cannot enter Green Lake or Lake Toolondo due to the differences in elevation. Environmental flows are released from water storages to meet the ecological needs of the waterway, mostly when natural flows are low. This water comes from an environmental entitlement - water that is legally set aside to support environmental values.

Why does Wimmera CMA release environmental water into the Wimmera River?

The Wimmera River has unique and highly valued natural features and supports many plants and animals. Without environmental flows, long periods of hot, dry weather cause pools to dry out or become super salty. A healthy river also supports recreational values such as fishing, enjoying a picnic, walking, bike riding, running or relaxing while watching the sun rise and set.

Does Wimmera CMA try to fill Lake Hindmarsh with environmental flows?

No. Natural flows from floods are required for it to fill.

Does Wimmera CMA provide an environmental flow to Yarriambiack Creek?

No. But since completion of the Wimmera Mallee Pipeline, a much higher proportion of natural flows resulting from high rainfall continue down the Wimmera River instead of being diverted into Taylors or Pine Lake and some go into Yarriambiack Creek. During times of large, continuous natural flows, water goes further up the creek, helping maintain its environmental condition. A proportion of environmental flows in the Wimmera River go into the Yarriambiack, but these flows are quite small and don’t flow far up the creek.

Winter Flows

The focus of the Winter Flows program is on providing water via the Wimmera Mallee Pipeline to several small wetlands in the northern Wimmera. As the pipeline can only supply small volumes, the objective is to fill low points in these wetlands to support habitat for fauna such as ducks, grebes and turtles throughout the year.

If you have any other questions please don’t hesitate to phone (03) 5382 1544 or send an email to wcma@wcma.vic.gov.au.

Wimmera Catchment Management Authority
www.wcma.vic.gov.au | 03 5382 1544 | 24 Darlot Street, Horsham 3400