25/03/2010 Swan and Canning rivers low oxygen

The Swan River Trust is monitoring low oxygen levels in the upper reaches of both the Swan and Canning rivers after this week's storm washed large amounts of organic matter into the rivers.

Swan River Trust River Systems Manager Mark Cugley said rapid drops in oxygen in waterways was a natural process that occurred after rainfall events washed large amounts of organic matter into the water, rapidly increasing the activity of micro-organisms.

"The Trust is monitoring the situation closely and we have both the Guildford oxygenation plant in the Swan River and the Camsell Way oxygenation plant in the Canning River running at full capacity, 24 hours a day," Mr Cugley said.

"We are still waiting for power to be restored to the second Canning River oxygenation plant at Bacon Street. This may take a couple of days but we are sourcing generators to supply power in the interim."

The Trust has received reports of fish deaths between the Middle Swan Bridge and Caversham, and also Woodbridge Reserve in Guildford in the Swan River. Crabs in the Upper Swan have also been seen leaving the water.

In the Canning River marron have been seen leaving the water at Yule Brook, Beckenham.

"We are currently investigating the fish deaths and it's likely the marron and crabs are leaving the water due to very low oxygen levels. It is possible the low oxygen levels may contribute to further fish deaths," Mr Cugley said.

The Trust is working with the Department of Water to oxygenate the water in the upper reaches of the Canning and Swan rivers to remediate the situation as soon as possible.

The Trust encourages the community to report any sightings of slow moving or sluggish fish by calling the office on 9278 0900, or after hours on 0419 192 845.

The Department of Health is warning people to avoid contact with water in Perth rivers and at beaches near stormwater outlets, due to contaminants being washed into these waters after Monday's storm.

The Trust reports changing river conditions to the community through the weekly Algae Activity Report and will continue to keep the public informed.

For more information about algal blooms visit www.swanrivertrust.wa.gov.au.