Monroe County's Griffy Lake will be closed to boating Tuesday and part of Wednesday to allow lake management to apply herbicides controlling for invasive plants.
Bloomington Parks and Recreation Natural Resources Manager Steve Cotter says Eurasian watermilfoil forms a dense mass at the water's surface, which can interfere with boating and fishing, negatively impact fish populations and water quality, and displace native plants.
"As an invasive plant, it doesn't really have many things that eat it or that control its population," Cotter says.
Cotter says the lake was last treated for the invasive plants in 2009, but a May 2016 survey revealed the Eurasian watermilfoil population has come back in the lake's east and north ends.
"A single segment of stem and leaves can take root and form a new colony," Cotter said in a statement. "Fragments can ‘hitch' a ride on boat propellers, and in live wells and bait buckets, and easily spread to other bodies of water."
Cotter says the herbicide being used will have a minimal effect on native plants.
The lake will close for boaters at 7 a.m. on Tuesday and is set to reopen at 1 p.m. on Wednesday.