Environment Protection Authority Victoria (EPA) is aware of a blackwater event, a naturally occurring phenomenon especially after heavy rain during otherwise dry conditions, at One Mile Creek, Wangaratta.
Downfalls of up to 69mm of rain that fell at Wangaratta on 27 January have caused an increase in catchment runoff into the creek, but due to the dry conditions upstream there have not been sufficient flows to move the water through the creek system.
Runoff from the catchment includes leaf litter and other debris, which has made its way into the One Mile Creek but has not been flushed through. This organic material is starting to decay and is causing the water to look black. This is known as a Blackwater event.
The black appearance of the water is due to the release of carbon compounds (including tannins) as the organic matter decays; like the process of adding water to tea leaves. Blackwater, with low level of dissolved oxygen may cause stress to fish, crayfish and other aquatic animals. When the dissolved oxygen reaches a very low level it can result in fish deaths.
The community is encouraged to report fish deaths to the EPA on 1300 EPA VIC (372 842).