Emu

Watching waterways

Wednesday 3 February, 2021
Goulburn Broken CMA and Goulburn Murray Water are monitoring water quality across the catchment after Friday’s rain.

In summer toxic blackwater events can sometimes occur when heavy rain washes leaf litter and other debris off the dry floodplains into the catchment’s creeks and rivers.

This can be exacerbated if water and air temperatures are high. The combination of debris-rich water with warm air and water temperatures can cause a sudden and dramatic drop in water oxygen levels and lead to what is known as a hypoxic blackwater event.

In our area, this is most likely to happen if there is very heavy localised rain in the Strathbogie Ranges in summer and debris is washed into nearby unregulated creeks, such as the Pranjip, Castles, Hughes and Seven creeks, which are tributaries of the Goulburn River.

Falls of up to 100mm were recorded in the Strathbogies on Friday and into early Saturday. Fortunately temperatures are forecast to remain relatively mild over the next few days. Flows from the Goulburn Weir increased from 1400 megalitres (ML) to 1800ML a day on Saturday. The increased flows will help dilute any debris-rich or poor-quality water that may enter the Goulburn River from the tributaries. We will continue to monitor water quality.

Friday’s rain provided a welcome boost to many of the region’s waterways, floodplains, native fish and wildlife as many of the unregulated creeks have had no or very low flows due to the hot dry conditions we’ve experienced in recent months.

Scientists from the Arthur Rylah Institute will be conducting their annual fish surveys in a number of these creeks in the next couple of weeks. Regular surveying helps track water quality and native fish health and numbers, particularly of threatened species such as Macquarie perch and trout cod.

If the community is concerned about water quality please contact 5822 7700 or reception@gbcma.vic.gov.au