City Council and Adelaide and Mount Lofty Ranges Natural Resources Management Board have proposed a trial of sodium percarbonate to kill off algal blooms.
They believe the chemical's active component, hydrogen peroxide, will
have a minimal impact on the aquatic environment because it can decompose
harmlessly into hydrogen and oxygen, within two days.
The resource board's sustainable landscapes manager Alan Ockenden said the chemical should kill algae without major side effects. "It could create a control algaecide with very low environmental impacts, much lower than other available products," he said.
"We're really just taking careful, small steps to see if this works." .
Under a proposed trial to be considered by councillors this month, a 105sq m section of the lake will be treated with a small amount of the chemical, and the effects monitored over the following two days.
The council has already applied to the Environment Protection Authority for permission to run the trial, to be carried out during an algal bloom. Algal breakouts caused the closure of the lake for most of January, but levels of the bacteria that cause the breakouts have since subsided.
Bacteria can release toxins that are potentially harmful to humans and animals. The resources board has had mixed results over two summers, by flushing water down the river from the Hope Valley Reservoir when bacteria levels rise.
The intent is to flush the bacteria from the lake before blooms form. But delays to water tests between Christmas and New Year meant high bacteria levels were not picked up soon enough to stop the January algal outbreak.
The public can make written submissions on the proposed chemical trial to the EPA, until March 21 2013.