One rain garden and two stormwater pond renovations were completed in November to treat stormwater before it reaches Martin and Coon Lakes. The projects will collectively treat 39 acres of residential development that previously were draining to the lakes with little or no treatment. They will keep 2,100 pounds of sediment and 5 pounds of phosphorus from reaching the lakes each year.

These waterbodies were priorities because both lakes are surrounded by homes and heavily used for recreation. Martin Lake is nearing the criteria for being removed from the State's list of impaired waters. Coon Lake has good water quality but is under pressure.

The rain garden was constructed in cooperation with a residential landowner along Hupp Street. Their property is a key location where drainage from 8 acres converged and entered a catch basin that piped stormwater to Coon Lake. Curb cuts on each side of the catch basin now intercept that water, allowing it to soak into the ground within the rain garden. Pollutant removal is estimated to increase by 52% compared to the pre-project condition. Mulching and planting of the gardens will be delayed until spring 2021 due to cold temperatures early in fall 2020. The property owners will maintain the garden.

The stormwater pond projects are redesigns and renovations of older ponds. Both ponds are on Martin Lakeshore within township-owned property. Both basins had filled with sediment over time and were providing little water quality treatment. Now, the basins are even larger than originally constructed to maximize pollutant removal. Pollutant removal is estimated to increase by 84% and 104%, respectively, at the two ponds. Linwood Township will own and maintain the basins.

These projects are part of a State Clean Water, Land and Legacy grant to the Sunrise River Watershed Management Organization. The Anoka Conservation District is managing the projects. Additional funds remain and will be used for similar projects in 2021.

Collaborators on these projects included the ACD, SRWMO, Martin Lakers Association, Linwood Township, and the City of East Bethel.

By the end of September 2020, both Coon and Martin Lakes will have new treatment of stormwater before that water reaches the lake. Two stormwater ponds at Martin Lake are being renovated. One new rain garden at Coon Lake is being constructed.

The two stormwater ponds already exist on the shores of Martin Lake at 228^th Place and 230^th Avenue (see map). Like a full vacuum cleaner bag, they have captured as much sediment and nutrients as is possible. To call them "ponds" today seems generous. Each will be made deeper than the original design, like replacing an old, full vacuum cleaner bag with an empty, bigger bag. Pollutant removal will be more than 50% greater than when the ponds were originally designed and new. Water reaches the ponds by pipes that capture water from several acres of surrounding neighborhood, including roads.

The rain garden at Coon Lake will capture curbside water that today is piped to Coon Lake without treatment. The curb will be cut creating entrances to the approximately 1 ft deep basin. Sandy soils allow quick infiltration of the water. A special underdrain ensures no standing water. Native plants create a garden appearance. The owner of the property on Channel Lake has agreed to maintain the garden.

Images show project locations and condition of the stormwater ponds before renovation.