1980’s: Lefroy Brook (WA). Pesticide residues: Dieldrin, DDT, Heptachlor

Monitoring WA River and Basins

Since about 1980 WAWA has intermittently sampled four river basins – the Warren, Preston, Collie and Swan Coastal – for pesticide residues. These samples have been taken either at permanent stream gauging stations, or at other marked points along the river.

The analysis of these samples has shown the consistent presence of dieldrin and DDT residues (except in the Collie River where no residues were found). Some heptachlor levels were also found; one extreme level of 0.170 ug/L was detected in Lefroy Brook (a tributary of the Warren River, near Pemberton) in December 1981. A significant proportion of the DDT and dieldrin residues exceeded the EPA criteria. The highest dieldrin level found was 0.019ug/L – also from Lefroy Brook in June 1982.

P46 Monitoring Pesticides – A Review – A Report to the Environmental Protection Authority by Peter A Rutherford. Environment Protection Authority. Perth Western Australia. Bulletin 407. December 1989.