Collaboration yields rain garden

A new 1,500-square-foot rain garden will provide water quality benefits to the Kinnickinnic River watershed and an educational resource to Humboldt Park students.

Groundwork Milwaukee partnered with Humboldt Park K-8 Charter School, Milwaukee Community Service Corps, and the Bay View Neighborhood Association to plant the rain garden at the school in September. Thirty neighborhood volunteers and 75 students planted over 1,000 native plants and grasses on what used to be asphalt playground.

On the surface, a rain garden simply looks like any garden. Its importance lies in how it gets its water and what happens to the water once it arrives. Stormwater runoff is precipitation that does not infiltrate into the ground or evaporate due to “impervious” surfaces like roofs, driveways, and sidewalks. Rain gardens provide shallow depressions that mimic the natural absorption and pollutant removal abilities of a forest by allowing stormwater runoff to be collected and slowly absorbed into the soil. 

“Rain is not the problem. It’s the pollution that the rainwater picks up as it runs over manmade surfaces,” says Mary Beth Driscoll of Groundwork Milwaukee. “Rain gardens capture rainwater, hold it, and then slowly release it into the soil. The rush of a storm is slowed and cleaned-quickly, neatly, and naturally.”

Humboldt Park’s rain garden will allow rainwater and snowmelt running off the dirty adjacent playground to slowly soak into the ground. Native plants in the garden will have deep roots to absorb the water.

Project funding came from grants from the National Fish and Wildlife Foundation, Bay View Neighborhood Association, Greater Milwaukee Foundation, and fundraising efforts by Humboldt Park School. Groundwork Milwaukee has also partnered with the Milwaukee Community Service Corps (a job training program) to build three other Milwaukee area rain gardens, with a special focus on the Kinnickinnic River watershed.

“Focusing on the KK River watershed has been our goal because the area is very urbanized-or built out. Over 90 percent of the watershed is hard surfaces, such as rooftops, roads, or parking lots, which means more polluted stormwater runoff because the water isn’t absorbed on site. This runoff directly contributes to the poor water quality in the KK River, and to flooding problems. Monitoring at a rain garden the team built at Cleveland Park has provided scientific data that rain gardens make a difference,” said Cheryl Nenn of Milwaukee’s Riverkeeper, whose staff conducted the monitoring. “Runoff from the rain garden site was cleaner than an adjacent paved control site, which contributed more sediment, bacteria, and pollutants to the KK River during several rain events this summer.”