It’s mid-afternoon on a beautiful summer’s day, and Square Lake Park is filled with people. Families lounge on the beach, while kids play in the shallow water. There are picnics and volleyball games, half a dozen people fishing from the pier, and a small armada of kayaks and stand-up paddleboards floating further out in the lake.
Square Lake is one of the clearest lakes in the Twin Cities area and ranks in the top 1% for water clarity in the entire North Central Hardwood Forest Ecoregion of Minnesota. Roughly 70% of the lake’s input comes from groundwater, and its famously clean and clear conditions make it an ideal destination for open-water swimming, scuba-diving, and family day trips. New park improvements underway this fall are designed to help keep Square Lake clean for years to come.
In 2020, the Carnelian-Marine-St. Croix Watershed District (CMSCWD) and Washington Conservation District worked together to conduct a sub-watershed analysis of land and wetlands draining to Square Lake. As part of this study, they identified numerous locations within Square Lake Park where better stormwater management could help to protect the lake from erosion and runoff pollution. This fall, Washington County is constructing stormwater treatment features, as well as planting trees, adding ADA accessibility to the beach and fishing pier, and rehabbing the entrance and parking lots. A grant from the Minnesota Clean Water Fund is helping to support the water quality components.
“This project has been my hardest project to construct,” said Mike Kline, a Project Manager with Washington County, when I stopped out to visit this week. “Usually I work on roads and you’re pretty limited in what you can do. Here we really had to be creative in ways to reduce runoff.”
The biggest change people might notice when they visit Square Lake Park next summer is a bioretention basin under the trees near the bottom of the north stairs. “Stormwater runoff used to wash-out the sand on the beach every time it rained,” says Dan MacSwain, Natural Resource Coordinator with Washington County Parks. Now, the basin will capture runoff from the gully before it reaches the lake, giving the water time to soak in and be filtered and cleaned by the plants.
As we walk down to the south end of the park near the boat launch, we can see a new stormwater basin at the top of the hill, designed to catch runoff before it goes downhill to the lake. Kline points out a small forebay at the bottom of the hill as well, which will make it easy for public works staff to clear out accumulated sediment from another drainage area. Looking around, I can see large swaths of erosion-control fabric and silt fence in numerous locations, as well as bright orange barriers placed on top of the storm sewer inlets. These features help to prevent soil from eroding and washing into the water during construction before the new vegetation gets established.
Mike Isensee, CMSCWD Administrator, emphasizes the importance of planning and partnership to make projects like this possible. “We were thinking about possible projects five years ago when we launched the subwatershed analysis,” he says. “It was perfect timing when we found out that the County would be updating Square Lake Park this year. I put together the application for a Clean Water Fund grant, passed it to Parks to submit, and now the project is underway!”
Construction at Square Lake Park is expected to wrap-up next week and a crew from the Washington Conservation District will be planting the bioretention basin next spring. By next summer, life at Square Lake should be back to normal – warm sand, clean water, and lots of reasons to stay and play.
East Metro Water 