Warmer weather could mean more floodwater fish deaths

EPA Victoria is warning that this week’s predicted rising temperatures are likely to cause an increase in the fish deaths being witnessed in flood affected Victoria.

Native fish need water that contains about 20% dissolved oxygen (DO). The State’s water monitoring network is showing dissolved oxygen levels below this in several locations, particularly in the north.

“The toll on Victoria’s inland aquatic wildlife from the floods is tragically going to grow as we see a combination of flood affected waters and warmer weather both of which will reduce dissolved oxygen levels,” said EPA Chief Environmental Scientist Professor Mark Taylor.

“Our advice is to continue to avoid contact with flood waters where possible because of the risk of contamination, not to eat any dead fish found in the waters and in the first instance, report dead fish sightings to EPA at 1300 EPA VIC (1300 372 842).”

The following rivers and water systems are experiencing low DO. This means fish deaths may occur.

Broken Creek

• Broken Creek has experienced very low levels of DO (

Murray River

• The main impacts on the Murray River are downstream of the Barmah Forest. This is because the returning floodwaters are high in organic matter from the Barmah Forest floodplain.

• The main stem of the Murray River is experiencing low DO downstream of Barmah. Fish deaths are expected here but the high flow rate may mean the fish are not highly visible, except in slow flowing areas.

• Levels of DO for the Murray River at Tocumwal and Wodonga are currently satisfactory

• The current peak of flood waters isn’t expected to reach Mildura until late November/early December, so fish deaths are expected to occur over a prolonged period.

Goulburn River

• DO dropped low for a few days in the Goulburn River at McCoys Bridge, between Shepparton and the Murray

• DO in the Goulburn River is currently satisfactory at Seymour and Shepparton.

Campaspe River

• The Campaspe appears to be satisfactory and acting as an important fish refuge right now with fish able to move from the Murray up the Campaspe River

Loddon River

• DO levels in the Loddon are poor below Loddon Weir, with very low DO and fish deaths have been reported.

Gunbower Creek

• The bottom of Gunbower Creek near Koondrook has been very low DO. There have been salvage efforts to move fish and freshwater crays out of this section.

Wimmera River

• The Wimmera River dropped to very low DO but no fish deaths have been reported yet.

New South Wales rivers

• For the NSW rivers, the Wakool River has very low DO. This is likely to impact the Murray River downstream of Swan Hill, near Boundary Bend.

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