1974 May – 1985 March: Fremantle Traffic Bridge. Pesticides detected: Aldrin, Chlordane, DDT, Dieldrin, Heptachlor, Lindane

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Swan-Canning Estuarine System – Environment Use and the Future (Thurlow et al 1986)

This report, was the culmination of a two-year study into the Swan-Canning River system.

Chapter 6, Section 311 was concerned with pesticide contamination, and reported the results of analysis of quarterly water samples taken from the Causeway and Fremantle Traffic Bridge.

The mean organochlorine pesticide levels found at the two sampling points are shown in the table below. These results are not significantly higher than the EPA criteria. However, the mean figures mask some peak residue levels in winter…

Table 10 Seasonal Means (ug/L) and peak level recorded of Pesticide Levels in the Swan Estuary (May 1974 – March 1985)

Causeway

Aldrin 0.001 (summer), 0.003 (winter)

Fremantle Traffic

Aldrin 0.001 (summer), 0.003 (winter)

Peak Level 0.018

Causeway

Chlordane 0.001 (summer), 0.001 (winter)

Fremantle Traffic

Chlordane 0.001 (summer), 0.001 (winter)

Peak Level 0.006

Causeway

DDT & Metabolites 0.002 (summer), 0.002 (winter)

Fremantle Traffic

DDT & Metabolites 0.002 (summer), 0.004 (winter)

Peak Level 0.03

Causeway

Dieldrin 0.005 (summer), 0.005 (winter)

Fremantle Traffic

Dieldrin 0.003 (summer), 0.005 (winter)

Peak Level 0.035

Causeway

Lindane 0.001 (summer), 0.001 (winter)

Fremantle Traffic

Lindane 0.001 (summer), 0.001 (winter)

Peak Level 0.02

Causeway

Hepatchlor 0.001 (summer), 0.003 (winter)

Fremantle Traffic

Heptachlor 0.001 (summer), 0.003 (winter)

Peak Level 0.06

Sampling commenced in 1974. By winter of 1975, levels of all pesticides had fallen significantly, possibly implying that levels before 1974 were much higher than from 1975 onwards.

Despite this decline, the peak levels for Aldrin, dieldrin and heptachlor all occurred in the winter of 1982.

The peak level for DDT occurred in 1975, with some smaller peaks in 1976. Since then DDT levels have been very low.

P49 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.