Algal bloom at Lake Seppings
Released 05 Nov 2010
Sampling by the Department of Water has revealed a bloom of Anabaena circinalis - a type of blue green algae.
Department of Water's Acting Regional Manager Chris Gunby said the algae was visible as small green dots, and made the water look murky.
"Winds can cause the algae to accumulate alongside a shoreline, where is it visible as a strong green discoloration," Chris said. "Then as it dies and decomposes, it can emit a strong odour.
"Bacteria breakdown the algae, and this can cause a white discolouration – almost like somebody has tipped white paint into the water." said Chris.
"As normal with blue- - green algal blooms, the Department of Health has advised visitors to avoid any contact with the water, and in particular to ensure that their dogs are not allowed into the water. Dogs can become ill even if they do not drink the water, through cleaning themselves after playing in it."
The cause of the algal bloom is not known, but the reduced winter rainfall, calm warmer spring period, combined with high water nutrient levels, may all have contributed.
"Our previous monitoring has revealed high nutrient levels in the lake, and this is likely to be caused by the stormwater that discharges from surrounding urban areas," Chris said.
"I would remind people of the importance of managing gardens in a manner that minimises nutrient run-off. The Department of Water can always give advice on such management.
"This type of algal bloom has occurred before in other waterways, like Lake Powell, but this is the first time we have monitored such a bloom in Lake Seppings.
"It is a matter of concern, as blue-green algal blooms often re-appear once they become established. As such, we are interested in finding out from any long-term local residents if they have ever observed a similar bloom in the past.
"Our own observations suggest such a bloom has not occurred in the past 10 to15 years, but longer term residents may have seen earlier blooms than this."
Any observations about previous algal blooms in Lake Seppings should be made to the Department of Water - please telephone 98425760.
Contact: Chris Gunby
Phone: (08) 9841 0107