1994 January: Olangolah Dam. Pesticide detected: DDT

“The only incident in which concentrations were found exceeding WHO guidelines (detection limits are generally less than 1/10th of the guideline values) was in the Colac Supply in January 1994. Samples from Olangolah Dam and the No 4 Service Basin were found to contain DDT at concentrations twice the WHO guideline of 2ug/L. Samples taken four days later showed negligible concentrations and none after treatment.” Physico-Chemical Quality Victorian Domestic Water Supplies (except Melbourne Metropolitan Areas) July 1995-June 1997. Australian Water Technologies.