Rain Gardens Contribute to Clean Water

by Cindy Gilberg

Water is a precious resource and clean water is even more valuable. Studies show that a significant percent of water pollution is the result of stormwater runoff – rain that runs off of rooftops, pavement and other impervious surfaces. Down it flows, carrying with it chemicals and trash from roadways and parking lots along with silt from soil erosion, eventually ending up in our major rivers and the Gulf of Mexico. Property damage along the way due to flash flooding and erosion can be catastrophic.

Rain gardens are a simple, relatively inexpensive solution to this complex and global problem. If each property owner were to plant a rain garden to intercept rainfall, it would have a huge impact on reducing stormwater runoff and ultimately provide an increase in overall water quality. Rain gardens are shallow basins that mimic natural watersheds by slowing down runoff and holding it temporarily—long enough to filter out pollutants and allow rainfall to be absorbed by the soil and plants. A rain garden can absorb 30-40% more rainfall than the same size area of lawn and can be designed to filter and treat up to 90% of all the rainfall events during a year in St. Louis (1.14 inches or less in 24 hours).
Missouri has an abundance of wetlands, streams and rivers and thus is blessed with a long list of reliably hardy native wetland plants for planting in rain gardens. These deeply rooted species make the soil more porous and absorbent. Many have great garden merit and fit into any landscape style. Rain garden designs using native plants range from naturalistic to traditional and even formal.
A wonderful resource on rain gardens close to home is Shaw Nature Reserve (a division of Missouri Botanical Garden) in Gray Summit, just 40 minutes from downtown. The Native Plant School offers classes on native landscaping and Chapter 2 of SNR’s Native Landscaping Manual is devoted to rain gardens, from design to planting and maintenance (www.shawnature.org).

Many regional organizations and companies are working together to provide education, expertise and support for rain gardens in St. Louis, including the Metropolitan Sewer District (MSD), Shaw Nature Reserve, Missouri Botanical Garden-Deer Creek Watershed Alliance, the Missouri Department of Conservation and MO Department of Natural Resources. Washington University is providing water quality testing on many of the pilot projects around town. MSD has been instrumental in assisting with many projects in St. Louis such as the rain gardens recently installed in a Habitat for Humanity neighborhood project and a series of rain gardens in a University City neighborhood. To show off these newly installed rain gardens, a Rain Garden Block Party is planned for May 15 from noon to 3 pm. (see www.deercreekallince.org for more info).

Rain gardens are sprouting up everywhere in residential neighborhoods, corporate campuses and public places. St. Louis’s City Garden incorporated a number of formal rain gardens as part of their overall design. Missouri Botanical Garden recently completed a large rain garden in their east parking lot. Another pilot project of Deer Creek Watershed Alliance and MSD is planned in Creve Coeur and one was just completed at the Mount Calvary Lutheran Church in Brentwood. When added up, all of these rain gardens together will make a significant difference in the future of our region’s water quality.

You can contact Cindy Gilberg at 314-630-1004 or email cindy.gilberg@gmail.com.

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