Minor fish kills in canal areas of the Gold Coast were reported following rainfall on
three occasions during summer 1995/96 (1 December, 11 and 24 January). Sampling
and analysis found chlorpyrifos in the water column at 0.05-1.2μg/L. The last of these incidents, at Runaway Bay, was investigated in detail. No new house
constructions with drainage to the canal were found, and records of under-slab
treatments at the nearest construction site did not coincide with the fish kill. Dow
concluded that garden spray runoff was the most likely cause, or washing of containers
into storm drains. The possibility of contamination from dirty equipment during a
storm event was also mooted. In response, Dow convened a pest control seminar in
conjunction with Gold Coast City Council, at which correct washing procedures,
equipment cleanliness and avoidance of storm events were stressed.
p179 https://apvma.gov.au/sites/default/files/publication/14756-chlorpyrifos-irr-environment.pdf