This rain garden in a Burnsville yard catches and filters runoff from the street.
Rain gardens gain popularity
Landscaping feature helps filter and treat stormwater runoff
Spring is sprung, spouting streams of runoff water that flow across the landscape from melting snow and rain. As the runoff makes its way to local lakes and streams, it absorbs lawn chemicals, animal wastes, automotive products, road salt and other pollutants from streets and yards. Where it moves rapidly, runoff gouges the soil, causing erosion and washing silt into local water bodies.
Lilies and other plants are growing in this rain garden in Maplewood.
As communities develop, they institute large-scale stormwater management projects – like holding ponds, stormwater drains and pipes – to handle the runoff. But homeowners and communities are finding that they can also help nature treat and control runoff through small-scale stormwater projects. One valuable tool in this effort is the rain garden.
Rain gardens are landscape features that soak up rain water, often from a driveway, the roof of a building or other area that cannot absorb precipitation. Landscaped with wild flowers, grasses and other native vegetation, rain gardens capture a few inches of rain. For about six hours after a rainfall, the captured water slowly filters into the ground, and then leaves the garden dry.
Unless specifically added to the design, rain gardens will not create ponds or wetlands; mosquitoes are not welcome! Birds, butterflies and beneficial insects will, however, be attracted to rain gardens.
Rain gardens are becoming more popular as more homeowners learn about them. When the Metropolitan Council helped fund a pilot rain garden program to filter runoff in the City of Burnsville, organizers expected about 30 percent of residents would want to install a rain garden. Instead, 85 percent of homeowners participated.
“The gardens really brought a lot of color and beauty to the neighborhood,” said Daryl Jacobson, Burnsville’s water resources specialist, “and runoff has now been reduced by 82 percent in the pilot project area.”
Burnsville ’s results are not unusual, according to a U.S. Geological Survey study, completed in partnership with the Council. “Properly designed rain gardens enhance infiltration,” said study author Lan Tornes, who reported some sites in the study had no overflow between 2002 and 2004. In addition, Tornes found that when water did overflow from rain gardens, it had lower levels of contaminants than the water coming into the gardens.
The size and shape of a rain garden depends on the soil conditions and the area that will drain into it, including the size of your roof, if you wish to capture water from the gutters. Experts recommend a mix of heights, shapes and textures in plant selection, as well as the use of native plants from reputable dealers. To assure color, select plants with different bloom times, or add colored foliage.
Consult your city, county or watershed office to learn about any grants or matching funds that might be available.