Tests show fire-affected dams are safe from contamination

A five-month program to test water quality in farm dams following the Cudlee Creek fires has concluded that negligible levels of contaminants from burnt treated timber have made their way into waterways.

In response to landholders' concerns about ash from burnt CCA-treated posts contaminating stock water, staff from the Hills and Fleurieu and the Murraylands and Riverland landscape boards initiated a water quality testing program. Concerns had started to increase after the first rainfall events in February 2020. Since then, water samples from 11 properties have been tested for the possible presence of chromium, copper and arsenic from burnt CCA-treated fence posts.

Environment Protection Authority Principal Scientific Officer (Chemistry) Dr Clive Jenkins said that after the Cudlee Creek fire, most of the burned CCA timber stockpiles were located and managed by Green Industries SA to minimise the release of pollutants to waterways and dams.

“But that effort could not track down all the CCA ash in the catchment, so landholders were offered the chance to have their water tested for free,” he said.

“Despite initial legitimate concerns, there have been negligible water quality issues for landholders in relation to CCA timber ash.”

Landholders were able to drop off water samples at local collection points and were sent the results after their water was analysed at the Australian Water Quality Centre. As well as dams, some samples were collected from rainwater tanks and groundwater bores.

The costs of analysis were covered by the Department for Environment and Water, while the Environment Protection Authority provided the results and technical advice to landholders.

In all tests at all sites, the concentrations of copper, chromium and arsenic were well below the Australian Guidelines for Fresh and Marine water Quality – Primary Industries (Livestock), and well below the Australian Drinking Water Guidelines.

Hills and Fleurieu Landscape Board Sustainable Landscapes Team Leader Susan Ivory said the results will provide peace of mind to landholders.

“It was great to be able to offer this testing and the results have meant there is one less issue that landholders have to worry about,” she said.

Ms Ivory added that with recent heavy rains saturating the soil profile and increasing runoff, the low level of contaminants found by the testing will hopefully bring peace of mind for landholders.She said the rainfall had encouraged re-growth of grasses and other vegetation which would help prevent any remaining CCA ash from finding its way into waterways.

Clickhereto see a map of the area covered by the Hills and Fleurieu Landscape Board.