Fire impacts on farm water quality can be managed

Learning how to stop sediment (ash, organic matter and soil) from washing into dams and waterways after a fire was the focus of a field day in early March for those impacted by the Cudlee Creek fire.

Over 20 people attended this Charleston event coordinated by Natural Resources Adelaide and Mt Lofty Ranges.

Presenters from Primary Industries and Regions SA (PIRSA), the Environment Protection Authority (EPA) and SA Water explained how erosion post-fire might impact water quality on farms, and what can be done to manage this.

Participants were shown how to install temporary fences to stop sediment entering dams and waterways using materials such as straw bales, old ringlock fencing and coir logs. The techniques were demonstrated by Natural Resources SA Murray-Darling (SAMDB) Basin’s Tony Randall and PIRSA’s David Woodard.

It was explained that in warm weather, if sediments and nutrients wash into dams they can cause a drop in oxygen levels, leading to fish and yabby deaths. These conditions can also promote green algal growth. Although unsightly and probably unappetising, green algae is not usually a problem for stock use. The EPA’s Dr Clive Jenkins said aerating water with pumps can be a useful way to control algae and cyanobacteria and to keep dam water healthy, especially in warm weather.

Dr Jenkins explained that free testing of dam water and waterways is available, to help detect any copper, chromium and arsenic (CCA). This risk is only considered relevant where stockpiles of burnt CCA fence posts had been located near water bodies.

He noted that of the results received so far from local properties tested, CCA levels were very low and of no concern.

The Department for Environment and Water is funding the testing by the Australian Water Quality Centre, with the confidential results interpreted by the EPA and emailed back to landholders.

This event was supported by the Adelaide and Mount Lofty Ranges (AMLR) and the South Australian Murray-Darling Basin NRM Boards, together with PIRSA, the EPA and SA Water.

If you would like to speak to someone about the quality of water in your dam or waterways, please contact Natural Resources AMLR staff at Black Hill 8336 0901 or Natural Resources SAMDB staff at Mount Barker 8391 7500.