by CHRIS ROGERS
It doesn’t take a microscope to see that Lake Winona, especially West Lake Winona, is chock full of lake weeds in summer. The profusion of invasive plants is in large part due to excessive nutrients in the lake, particularly phosphorus. It is an old problem, but local governments are close to having a game plan to fix it.
From spray painting storm drains to planting native shoreline plants, from installing rain gardens throughout Winona to scaring off Lake Winona’s goose population — there has been a big push by the citizen-led Healthy Lake Winona organization and the city itself to try to clean up Lake Winona. However, those have been piecemeal efforts. The big study currently underway — the Gilmore Creek-Lake Winona Targeted Implementation Assessment — will provide a blueprint for how to actually solve the problem.
Saint Mary’s University (SMU) senior Severin Seifert is helping inform that blueprint. Last Friday, he threw a pair of coolers and a big pole with a water bottle on the end into a university van and grabbed a muffin for the road. Tracing the path of water that flows into Lake Winona, Seifert stopped at eight spots along the Gilmore Creek-Lake Winona watershed, starting upstream of campus and working his way down to Boller’s Lake, Lake Winona, and ultimately, the outflow where all that water slowly flows into the Mississippi River. At each stop, he dipped the pole into the creek and filled several bottles, then tucked the bottles into a cooler to keep them cold until they can be analyzed at the lab. “We see if phosphorus is getting used up by [organisms] in the creek. If not, then Lake Winona gets kind of gross,” Seifert explained.
Seifert and other students working for SMU Assistant Professor of Biology Joshua Lallaman are measuring the phosphate, nitrate, chlorophyll, and clarity of water from Wildwood Drive to the East End. Consultants hired by the city of Winona and Winona County are using Lallaman’s data to identify where all of Lake Winona’s excess phosphorus is coming from and what strategies would be most effective at reducing it. “We’re trying to provide actual, real data over a long time period to better inform where perhaps these pollutants are a problem to better identify the sources of pollution within the watershed,” Lallaman explained.
There are a few potential sources. For starters, excess phosphorus and nitrogen could be coming from farm fields and ridgetop land surrounding Gilmore Valley. Secondly, it could be coming from Boller’s Lake, the algae-filled pond near Goodview where lots of sediment from years of erosion has settled. Alternatively, the nutrients could be coming from Winona’s storm sewer system, which funnels rainwater and phosphorus-rich yard waste to the lake. Finally, the excess phosphorus might be old phosphorus that has built up in the sediment on the bottom of Lake Winona over years and is now circulating within the lake.
The county’s consultants are using a combination of Lallaman’s hard data, additional data on stream flow and precipitation, and computer modeling programs to figure out which of those potential sources are contributing the most phosphorus to Lake Winona. Lallaman reported that his initial results show that Boller’s Lake is not a major contributor of phosphorus and that excess nutrients are coming from upstream of campus, but that a significant part of Lake Winona’s problems lie within Winona city limits. Lallaman’s results could not distinguish between phosphorus entering the lake from Winona’s storm sewers and old phosphorus cycling within the lake; the county consultant will use computer modeling and lake sediment core samples to try to parse that out.
“I think we’re all expecting to make slow, steady progress with erosion and runoff in town,” Healthy Lake Winona member Gabe Ericksen said. “I think we’re expecting to have to do something pretty serious to address the [preexisting] phosphorus in the lake.”
If old phosphorus cycling within Lake Winona is a major part of the lake’s problems, one potential solution would be to dredge the lake and remove that phosphorus-rich sediment. East Lake Winona was dredged around the turn of the millennium. West Lake Winona has not been dredged in recent history.
The targeted implementation assessment is expected to be completed next spring. It will include a list of recommended projects with cost estimates and information on how big of a dent they would make on Lake Winona’s phosphorus levels. That information will allow local governments and citizens to make sure they are getting the best bang for their buck when they invest money in on-the-ground projects, Winona County Water Planner Sheila Harmes explained. Asked how the plan’s recommendations would be funded, Winona Sustainability Coordinator John Howard said, “I can’t really say too much until we see what the recommendations are, but we’re going to have to find ways to find funding for those projects.”
“The results will allow us to address the problems, whatever they are shown to be,” Healthy Lake Winona member and Winona City Council member Pam Eyden said. “Then we can apply for grant funds and start doing something about it.”
The county expects to hold public input meetings before the targeted implementation assessment is finalized next spring. Keep reading the Winona Post for more information.