After twenty years of community advocacy, public investment, scientific research, and targeted project implementation, Lily Lake in Stillwater achieved a major milestone this year when it was officially removed from the State of Minnesota’s Impaired Waters List. On Friday, September 30, Friends of Lily Lake will celebrate this return to clean water with a family-friendly community event at Lily Lake Park.
“Historically, Lily Lake was a local and regional gem,” says Matt Downing, who serves as administrator for the Middle St. Croix Watershed Management Organization (WMO). “Over time, as Stillwater grew and became more developed, however, water quality went downhill.”
When commercial and residential neighborhoods surrounding Lily Lake were constructed, it was standard practice to direct storm drains straight into lakes and rivers without treating the water first. As a result, this formerly pristine lake began to accumulate sediment, nutrients, litter, and debris from the surrounding watershed. By 2002, algae blooms were common and phosphorus levels in the water had climbed so high that the Minnesota Pollution Control Agency deemed Lily Lake to be officially impaired.
In 2006, the City of Stillwater and Middle St. Croix WMO set a goal of reducing phosphorus flowing into Lily Lake by 145 pounds per year to prevent harmful algal growth and improve water clarity. Over the past 16 years, the city and WMO have worked together to implement dozens of lake-improvement projects, including stabilizing eroding gullies, redesigning the city-owned boat launch with porous pavers and native plants, installing raingardens in surrounding neighborhoods, and retrofitting parking lots and stormwater ponds in commercial areas.
“The Lily Lake delisting has been a massive multi-year, multi stakeholder project — both public and private — that took thousands of hours of collaboration and outreach to reach this point,” says Bryan Pynn, a watershed restoration specialist who helped to design numerous projects installed by the Middle St. Croix WMO and Washington Conservation District. “Clean Water Funds from the state have been instrumental to funding stormwater reduction projects. These grants have also helped the WMO to engage more community partners and create a larger visual presence in the watershed.”
Without a doubt, community engagement has been the key to success in Lily Lake’s restoration story. In Stillwater, the city and private landowners have constructed 336 raingardens and more than 100 additional clean water projects. Volunteers have adopted 235 storm drains and also help to care for neighborhood raingardens on city streets. Friends of Lily Lake and Sustainable Stillwater engage volunteers for planting projects, buckthorn removal, and community clean-up events. Most recently, Friends of Lily Lake has led a community visioning process to think about what Lily Lake might look like in the future and how the community will use and interact with the lake.
“To restore Lily Lake, we’ve had to put it all together,” says Downing. “It’s required water monitoring, public education and engagement, modeling, and project implementation.” The last step required to clean-up Lily Lake and return it to a clear water state was a new infiltration basin, constructed in 2021, and an in-lake alum treatment that was conducted this year in May.
The Friends of Lily Lake community celebration on Friday, September 30, 5-7:30pm will include food, music, roasted s’mores over a campfire, and kids nature activities. There will also be a short program at 6pm to officially commemorate the de-listing of Lily Lake. The event is free and open to all.