Southern Spring flow 2019 - Update #5 - 17 October 2019

2019
Commonwealth Environmental Water Office
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The Southern Spring Flow has reached the Coorong!

Objectives Provide food and shelter for native fish and other aquatic animals along the River Murray, from Hume Dam to the Coorong.
Start date 1 August 2019 (Hume Dam release)
Total duration 1st flow (1 Aug) – 2-3 weeks
2nd flow (1 Sept) – planned to finish on 19 October 2019.
Flow rate Combined with other flows to target up to 2.2m (15,000 megalitres/day) downstream of Yarrawonga Weir.
Target areas River Murray channel and key wetlands and creeks in Barmah-Millewa and Gunbower-Koondrook-Pericoota forests, Edward-Wakool, Lake Kramen (Vic Hattah-Kulkyne Lakes complex), wetlands in Chowilla, Coorong and Lower Lakes.

Where is the flow now?

Pelicans taking a break on the edge of the Coorong. Photo: CEWO

The flows released in both August and September have now reached the Lower Lakes and are providing small flows over the barrages into the Coorong.

Southern Spring Flow is wrapping up

Releases from Hume Dam have decreased, with the Southern Spring Flow set to end on 19 October 2019.

We manage our water to respond to the conditions. Rainfall and inflows from Victorian tributaries in July/August were sufficient to provide natural cues for deliveries, and steady increases to Victorian Murray and Goulburn allocations. The latest Northern Victorian Resource Manager update notes dry conditions in September, a reduction in inflows and catchments starting to dry.

In response, the flows will finish ten days earlier than planned and be reduced by around 50 gigalitres. The water saved will be valuable for the environment in the future if the dry conditions continue.

The objectives of the Southern Spring Flow are still expected to be met.  The mid-Murray has received a productivity boost to support native fish and fringing wetland vegetation. Ongoing monitoring will continue, with results made available in coming months.

Extent of the Southern Spring flow (dark blue line) as at 30/9/2019, which has now reached the Lower Lakes.

Stormy weather helps deliver fresh water into the Coorong

Flows into the Coorong via Tauwitchere Barrage. Photo: Geoff Gallasch

While the Southern Spring Flow has benefited upstream rivers and wetlands, the water that returns to the Murray River channel continues to bring benefits downstream, all the way to the Lower Lakes and Coorong.

Water from the Southern Spring Flow is being used to dilute the hyper (or highly) salty Coorong—internationally critical shorebird habitat. Many parts of the Coorong are more than two or three times saltier than the ocean!

Barrage operators at the Lower Lakes rely on information from the weather bureau and local community to time the release of freshwater and open some barrages just before stormy weather. Storms which create ocean swells and strong winds help to push both freshwater and seawater further into the Coorong.  Careful timing of the release of freshwater over the barrages to combine with in coming seawater enables water managers to reduce the salinity of the Coorong and get the most benefits for the environment with small volumes of freshwater.

Satellite imagery monitoring flows in Millewa forest

Australasian Bittern looking for a snack Photo: Richard Hall

Forest site managers work hard and spend many hours in the bush tracking flows, plants and animals. These on-ground efforts are invaluable, and we are using some modern technology to complement observations from boots on the ground!

Satellite images on the next page (courtesy MDBA) demonstrate how the Southern Spring Flow was used in a targeted way to water only select wetlands and low parts of the Millewa forest.  The dark areas on the bottom (September) image show water that moved into Reed Beds Swamp, Coppingers Swamp and Duck Lagoon in Gulpa Creek wetland complex (Millewa Forest, NSW) from July to September 2019.

These wetlands were specifically targeted to receive water for the environment as they are home to a number of native waterbirds, including the threatened Australasian Bittern.

We are collaborating with the Victorian Environmental Water Holder, NSW Department of Planning, Industry and Environment, SA Department for Environment and Water, Murray-Darling Basin Authority, Goulburn-Broken CMA, WaterNSW and Goulburn Murray Water.

Satellite images (courtesy MDBA) demonstrate how the Southern Spring Flow was used in a targeted way to water only select wetlands and low parts of the Millewa forest. The dark areas on the bottom (September) image show water that moved into Reed Beds Swamp, Coppingers Swamp and Duck Lagoon in Gulpa Creek wetland complex (Millewa Forest, NSW) from July to September 2019.

More information: The Southern Spring Flow 2019

Local Engagement Officers

Richard Mintern (Mildura, VIC)

Michelle Campbell (Berri)