Waterways and algal bloom watch for summer 2010-11
Released 30 Nov 2010
Following one of the driest winters on record in the south west land division, conditions in certain waterways are likely to result in more algal blooms than normal
The department's Water Science Branch Manager Malcolm Robb said the reduced rainfall over the winter months and subsequent reduced flows in South West's waterways has increased the potential for algal blooms.
"An especially dry winter like this one does not necessarily lead to increased algal growth in estuaries, but there may an increased growth in river pools as they dry and stagnate," Mr Robb said.
"When the rivers dry earlier than normal there is less dilution of nutrients and in algal bloom prone areas this may lead to increased growth, or a shift in the type of algae, possibly to more toxic species."
Mr Robb said the department had already picked up increased algal activity in the Hardy Inlet and the lower reaches of the Scott River, and there had been a small fish kill incident in the Wonnerup estuary last week.
The department's monitoring has shown algal growth is also increasing in the Serpentine and Murray rivers of the Peel Harvey, which happens every summer, and also in the Vasse River and wetlands, which is also an annual summer event.
The monitoring is planned to continue over the summer period.
"The department has regular monitoring programs in key waterways of the South West," Mr Robb said.
"The samples are analysed and the reports are circulated to key agencies responsible for public health including: local shires and the Health Department.
Mr Robb said the public should stay alert for warnings issued by the Health Department regarding potential harm from contact with waterways, algae or dead fish.
"Fish kills generally occur from a lack of oxygen in the water column which is caused by the decomposition of algae and not necessarily a result of algal toxicity," Malcolm said.
"If there are no warning signs and you come across a serious bloom or large number of dead fish, we ask you contact the regional office of the Department of Water, the Department of Fisheries or your local government authority," he said.
"If the incident is within the Swan River area, contact the Swan River Trust."
Contact: Peter Collins
Phone: (08) 6364 6848