Rain gardens can substantially reduce the impact on the environment from stormwater and building rain gardens is an easy way for homeowners to help minimize their contribution to water pollution.
When rain falls on natural areas, such as a forest or meadow, it is slowed down, filtered by soil and plants, and allowed to soak back into the ground. When rain falls on impervious surfaces like rooftops, roads, and parking lots, rain does not soak into the ground, and storm water runoff is created. An acre of impervious area results in approximately 26,000 gallons of runoff from a one-inch rain as compared to little or no run-off from a natural area. Stormwater runoff picks up pollution such as fertilizer, pesticides, sediment, motor oil, litter, and pet and yard waste. It delivers these pollutants to local streams and rivers.
In most cities, stormwater runoff does not go to a treatment plant. Instead, the contaminated runoff flows directly into streams and rivers. Upstream from you, stormwater runoff goes into source of your drinking water. Downstream, other cities use your stormwater runoff for drinking water. During large rainfall events, stormwater runoff can cause flooding. Further, excess water flowing into streams will cause bank erosion problems.
Backyard rain gardens are a fun and inexpensive way to improve water quality and enhance the beauty of your yard or business. Rain gardens are placed between stormwater runoff sources (roofs, driveways, parking lots) and runoff destinations (storm drains, streets, streams).
A rain garden is a shallow depression in the ground that captures runoff from your driveway or roof and allows it to soak into the ground, rather than running across roads, capturing pollutants, and delivering them to a stream. Plants and soil work together to absorb and filter pollutants and return cleaner water through the ground to nearby streams. Rain gardens also reduce flooding by sending the water back underground, rather than into the street. Besides helping water quality and reducing flooding, rain garden plants provide habitat for beneficial insects and wildlife.
The rain garden fills with a few inches of water after a storm, and the water slowly filters into the ground. Because water is only in the rain garden for a day or two, it doesn’t become a breeding ground for mosquitoes.
Information about constructing a rain garden
- North Carolina Extension Service information (very complete and specific to the Catawba-Wateree region)
- University of Nebraska publication on rain garden design