On a sunny summer’s day in 2020, my son and I headed to Carver Lake Park in Woodbury to try out the new bike park playground, ride the single-track trails, and hide clues for a Water Pollution Mystery Game. Carver Lake Park is an urban gem, filled with towering trees, paved walking trails, multiple playgrounds, a public swimming beach, and 5.5 miles of mountain bike trails. Unfortunately, on the day that we arrived, we discovered that the beach was closed due to a blue-green algae bloom.
This summer, visitors to Carver Lake Park will discover a newly renovated parking lot, complete with a 5220 sq ft raingarden and 8000 sq ft of native plantings designed to filter and treat polluted runoff, as well as create habitat for birds and pollinators. The raingarden will capture 0.7lb of phosphorus, which is enough to prevent 350 pounds of algae from growing in the lake!
“The City of Woodbury planned to do a parking lot improvement at Carver Lake Beach parking lot and wanted to incorporate stormwater treatment and native plantings as part of the project,” says Paige Ahlborg, Watershed Project Manager at Ramsey-Washington Metro Watershed District (RWMWD). “They approached us with the idea and we provided technical and financial assistance through our stewardship grant program. We were also able to apply about $8,000 in Clean Water Funds through a watershed based funding grant to the cost of the rain garden.”
Andy Novak, a landscape designer at Washington Conservation District, worked with RWMWD and City of Woodbury to design the Carver Lake raingarden and create a planting plan. Some of the plants in the raingarden include Monarda fistulosa, commonly known as bee balm or wild bergamot, Panicum virgatum “switchgrass,” Baptisia australis “blue false indigo,” Eryngium yuccifolium “rattle-snake master,” and Dalea purpurea “purple prairie clover.” You won’t see much if you head there this spring, however. “It was planted in the fall,” explains Novak, “so all one can see is mulched patches in the parking lot.”
Carver Lake is a small, deep lake in Woodbury that outlets to Fish Creek, a tributary to the Mississippi River. The lake is officially listed as impaired due to chlorides from winter road salt and mercury from atmospheric deposition. It is usually safe for swimming, but anglers are advised to limit the amount of fish that they eat from Carver Lake. Ramsey-Washington Metro Watershed District has classified the lake as “at risk,” due to elevated phosphorus levels which sometimes cause blue-green algae blooms, as seen last summer. When this happens, the water turns bright green like pea soup and it is not safe for people and pets to swim.
As with most urban lakes, the phosphorus in Carver Lake comes from stormwater runoff. Rain and melting snow pick up dirt, leaves, grass clippings and other debris and carry it to the lake via stormwater pipes that are buried beneath roads and parking lots. In addition to building the new raingarden last summer, RWMWD and Woodbury have worked to reduce the impacts of stormwater runoff by narrowing residential streets, installing raingardens along roadways to capture and infiltrate runoff, re-designing existing stormwater ponds to filter out more phosphorus, installing porous pavement in a residential cul de sac near Carver Lake, and stabilizing a wooded ravine within Carver Lake Park.
The public also plays an important role in helping to protect area lakes from runoff pollution. The Adopt-a-Drain program – www.adopt-a-drain.org – encourages people to sweep dirt and yard waste off of sidewalks, driveways and curb-lines throughout the year and adopt local storm drains in their neighborhoods. Residents are also encouraged to limit the use of road salt, fertilizer, and lawn chemicals to avoid polluting lakes and streams.
To find updates on mountain bike trail conditions at Carver Lake Park, go to: https://trails.morcmtb.org. The trails and bike playground are maintained by volunteers from the Minnesota Off-Road Cyclists (MORC). Currently, trails are closed until the spring thaw is complete.
To learn more about water quality in the Ramsey-Washington Metro Watershed District and find stewardship grants for projects at your home, go to: www.rwmwd.org.
If you stop by Carver Lake for a picnic, bike ride, or day at the beach this summer, take a moment to stop and smell the flowers in the new parking lot gardens while you are there.