2011 December: Candowie Reservoir (Vic) Phillip Island Water Supply. Pesticide: Monocrotophos

6/12/11: The insecticide, Monocrotophos was detected at 20ug/L in Candowie Reservoir at inlet to Water Treatment Plant. In the 2004 Australian Drinking Water Guidelines, Monocrotophos had a guideline level of 1ug/L. It did not have a guideline level in the 2011 Guidelines.

The level detected therefore was 20 times higher than the level determined to be “safe” in 2004. Probably the most serious pesticide incident in a domestic water supply in Victoria since the 1970’s. How much was removed during the treatment process? Was the source determined?

“The herbicide/pesticide, monocrotophos exceeded the ADWG health-based
guideline value during the 2011/12 reporting period. Westernport Water were not advised of this exceedence by their consultant laboratory and were therefore unable to take any remedial actions in response to the detection. It is important to note that this result was obtained in the raw water, and the health-based guideline values apply in the treated water.”