1980 – 1981: Waters off Rottnest Island. Pesticides detected: Dieldrin, DDT

Study to establish baseline levels of contaminants and nutrients in marine waters of WA (Chegwidden 1981)

This study was conducted as part of the marine quality assessment programme (Map 15) in 1980/1. The site chosen for the study was the CSIRO Rottnest Island 50 m station. This was in 50m of water, 3.3 km due west of Cape Vlaming, Rottnest Island.

Water samples were taken at this site on 11 occasions between April 1980 and January 1981, from the surface and at depths of 1.5 and 20 m. 10 per cent of the 120 samples gave positive results for dieldrin and DDT plus metabolites. The highest levels found were 0.027ug/L for dieldrin and 0.01ug/L for DDT and metabolites. The analytical limit of detection was 0.001ug/L for both pesticides. Most levels just exceeded that limit.

The author concluded that organochlorine pesticides were present in the waters off Rottnest Island.