AUBURN — Lake Auburn watershed officials will ask the Maine Department of Environmental Protection to use a copper sulfate algicide to prevent another fish-killing algae bloom.
The Lake Auburn Watershed Protection Commission has scheduled a public hearing from 6 to 8 p.m. March 27 in Auburn Hall to discuss its plans.
Lake Auburn is the drinking water supply for Lewiston and Auburn.
"Getting a permit from the state is a long process, so we want to be prepared," said Lynn Richard, Lake Auburn watershed education and outreach manager. "We want to be ready because the algae will be ready to grow. We need to give the state enough time to review the application. It's probably going to take the rest of the month for us to get the application completed."
Water quality officials in mid-September discovered more than 200 dead trout along the shore or floating close to the shore. They blamed the kill on high phosphorous levels in the lake that encourage common blue-green algae to grow.
As the algae grows and dies, it sinks into the lake, decaying and using up oxygen in the process. Fish, such as trout, that prefer the cooler bottom of the lake are starved of oxygen.
Engineers found elevated phosphorous levels and evidence of waterside erosion at several points along Lake Auburn's feeder tributaries. Those include Little Wilson Pond, the Basin and Townsend Brook.
Copper sulfate is an algicide used to treat algae blooms in swimming pools and aquariums. It was one of the options discussed last month when the watershed group released results of its study of the fish kill.
"We are not sure the algae will return," Richard said. "But if it does, it's going to start in the spring and the early summer. And we want to be ready."
The watershed group's plan calls for using an approved algicide applied by licensed applicators, Auburn Water District Superintendent John Storer said in a written statement.
"The goal is to halt short-term decline of the lake and at the same time develop strategies to assure high-quality drinking water for the long term," Storer said in the statement. "We want to hear from our customers and from watershed residents if they have any questions or concerns."