Chippewa Valley Times

Covering over 7,600 acres, Green Lake is one of Wisconsin's largest and deepest natural inland lakes. It is a significant resource for the local community, with its rich Ho-Chunk tribal history and various recreational activities. However, the lake faces challenges due to excess phosphorus at two inlets: the Silver Creek Estuary and the County Highway K Marsh. This issue has led to toxic blue-green algae blooms, resulting in beach closures.

The Green Lake Association (GLA), with its 1,000 members, is addressing this problem by collaborating with the Center for Limnological Research and Rehabilitation (CLRR) at UW-Stout. Bill James, CLRR founder and director, stated, "The Green Lake Association is being proactive. They’re doing the right thing."

Green Lake's water quality has been classified as "impaired" according to state standards. Stephanie Prellwitz, CEO of GLA, emphasized the urgency of reducing phosphorus levels: “The lake is giving us warning signs... It’s important we take the necessary steps to reduce phosphorus sooner rather than later.”

To tackle this issue, GLA is working with CLRR and Stantec, a sustainable engineering consulting firm. The collaboration involves testing sediment cores from the lake's inlets to determine phosphorus diffusion rates. "We’re not hitting our long-term goals," Prellwitz noted. "We need a 60% reduction in phosphorus just to remove the lake from the impaired waters list."

Warmer winters have also contributed to algae growth by extending periods when lakes remain unfrozen. Prellwitz remarked that warmer water allows lakes "to biologically cook for longer."

CLRR is conducting sediment analysis in its lab at UW-Stout’s Jarvis Hall Science Wing. Conor Dougherty and Andrew Schneyer are involved in this process under James' guidance. James explained that bays are manageable areas where efforts can be concentrated: “One of our goals is to try to stop what’s coming into the lake.”

James has extensive experience as a research aquatic biologist and holds a master’s degree in limnology from Kent State University.

While plans for treating Green Lake are still under development, CLRR has used alum treatments successfully on other lakes listed as impaired within Wisconsin.

James highlighted the importance of these efforts: “There’s a purpose to this — preserving the beauty of Wisconsin Lakes... It’s human-driven — we create the problem and have to solve the problem.”