New website archives more than a century of research to help conserve Wisconsin’s treasured Green Lake

April 6, 2017

Nelson Institute students and faculty have developed a website to assist researchers, inform the public, and boost conservation efforts around central Wisconsin’s Green Lake. 

Measuring 236 feet at its lowest point, Green Lake is the deepest natural inland lake in the state, providing habitat for trophy lake trout and other unique coldwater species. About 90 minutes northeast of Madison, the Green Lake watershed covers 107 square miles and contains 141 miles of rivers, 655 acres of lakes, and more than 5,000 acres of wetlands.

But the Wisconsin Department of Natural Resources has designated Green Lake an “impaired waterway” due to its low concentration of dissolved oxygen. Green Lake also has a high concentration of phosphorus and degraded habitat – the result of land runoff and other nonpoint source pollution from across the watershed.

The Green Lake Association (GLA), along with various partners, is working to address these issues. In 2015, the organization partnered with Nelson Institute scientists to examine the lake ecosystem and find solutions to the problems it faces. The recently published website, at, developed by Nelson graduate students working in collaboration with GLA, is one step in that ongoing partnership.

"There has been lots of great
research and data collection
on Green Lake... but the data
is collected by multiple entities
at various times," Prellwitz says.
"When asked a basic question
like, 'What data is available?',
it was virtually impossible for
us to answer."

Housing hundreds of resources, from scientific publications and agency reports to best management practices and more – and spanning more than a century of research – the website provides a “one-stop shop,” explains GLA executive director Stephanie Prellwitz. She says the site will support important new research on Green Lake by displaying all the studies, and their results, that have already been done.

“There has been lots of great research and data collection on Green Lake, some of it dating back to 1905. But the data – both historic and current – is collected by multiple entities at various times,” Prellwitz says. “When asked a basic question like, ‘What data is available?’, it was virtually impossible for us to answer. As a result, projects were delayed or failed to get off the ground.”

The website solves that problem, helping to illuminate the expansive data and research that has been collected on the iconic lake.

Green Lake map

“When I look at the web portal, I'm really proud of all the work that has been done on Green Lake. It is a special place that has drawn a lot of people to it over the years,” Prellwitz says.

She says the idea to create an online resource emerged in 2013 as the first Lake Management Plan for the watershed, which summarized the challenges facing the lake and strategies for mitigation, was prepared. When working on the plan, members of the team were surprised at how much data was available that they had never before heard of.

“We were surprised to discover pieces of data or research projects that we had no idea existed,” Prellwitz recalls. “I would never have guessed that we have reports dating back to the late 1800s about Green Lake. As lake managers and decision makers, it's critical to know what has been done so we can more effectively establish a path forward. We do not have unlimited resources, so it's important we utilize historic data to its full potential by learning from it and building off of it.”  

The web portal can act as a launch pad for critical thinking and research on Green Lake, helping GLA and its partners improve Green Lake’s water quality, so future generations can continue to enjoy the watershed and the services it provides.

“We recognize that, given the water quality issues on such an important lake, we have an opportunity to use Green Lake as a test case to establish a model for cleaner lakes throughout the Midwest,” Prellwitz says. “It's going to take big minds and significant efforts to change the trajectory of Green Lake. The web portal is one important piece in a larger ongoing strategy.”