Beach health study highlights dangers of stormwater
Released 25 Jun 2007
Microbes and heavy metals contaminate stormwater that flows onto some of Perth's most popular beaches, the first comprehensive study on beach outfalls has found.
The study by the Department of Water looked at 65 stormwater drains discharging onto beaches from Wanneroo to Rockingham.
It found that at many locations contaminant concentrations exceeded established health and environmental guidelines.
Author of the report, Principal Environmental Officer with the Department of Water, Frances D'Souza said the information from the study would be used by local governments in developing plans to manage their stormwater.
"The report recommends that local governments investigate the source of the contaminants (for example dog droppings or vehicle wear and tear) in their areas and act to reduce loads entering stormwater drains and basins," Dr D'Souza said.
"Once cleaned of contaminants, the stormwater can then be diverted to groundwater to help recharge the aquifer," she said.
Dr D'Souza said she had been surprised by the concentrations of some of the contaminants found in the stormwater.
"Microbes and heavy metals were found in higher concentrations with nutrients, petroleum hydrocarbons, organic chemical compounds and suspended solids also present in the stormwater," she said.
Nine regions were surveyed in the study. These were: Wanneroo, Joondalup, Cambridge, Cottesloe, Stirling, Scarborough, Rockingham, Shoalwater and Safety Bay.
Heavy metals including aluminium, copper, iron and lead were found in particularly high concentrations in the Joondalup, Stirling, Scarborough and Cottesloe regions with some levels exceeding environmental guidelines by 21-fold.
"Microbial quality (an indicator of risk to human health) in the swash zone, an area where swimming is most likely, was also poor with seven of the nine regions exceeding primary contact guidelines. Four regions (Rockingham, Safety Bay, Stirling and Cottesloe) exceeded these guidelines at least six-fold.
"The microbial quality of the actual stormwater was even higher with recordings up to 20 times the guidelines for secondary contact (activities other than swimming or wading) in six of the regions. This is of special concern because children are often attracted to stormwater channels on beaches as places to splash and play.
"Based on the results of this study local government authorities such as the City of Rockingham have already started an assessment of their stormwater management.
"The public can help their local government to clean up stormwater by picking up dog droppings; maintaining their vehicles by fixing oil leaks and tyres; collecting leaves and lawn clippings; washing cars on lawns and disposing of paints and oils through council-provided methods," Dr D'Souza said.
The study was funded by the Swan Catchment Council and the Department of Water with the microbial analyses funded by the Department of Health.
Contact: Peter Collins
Phone: (08) 6364 6848 / 0434 603 441