Rain gardens are small depressions, vegetated with shrubs, grasses and flowering perennials, which promote infiltration of rainwater. They are specifically located to catch rainwater in the form of runoff from urban and/or impervious surfaces.
HOW DOES A RAIN GARDEN FUNCTION?
Lawn fertilizer, pesticides, oil and other car fluids, and other harmful substances wash off roofs and paved areas flowing into streams and lakes as urban stormwater runoff. Nearly 70% of urban runoff is polluted*.
A rain garden is designed to “catch” runoff from a roof, driveway, parking lot or other impervious surfaces. It helps to reduce the polluted runoff that would otherwise flow directly into a local stream. The rain garden fills up with runoff which then slowly filters pollutants prior to soaking into the ground. A rain garden allows about 30% more water to soak into the ground compared to a patch of lawn.** These benefits help to improve water quality and local aquifer recharge.
Rain gardens also bring beauty to urban landscapes, can incorporate recycled materials and provide habitat for birds and butterflies, while acting as “mosquito cemeteries.
*Rain Gardens of Western Michigan; http/www.raingardens.org/FAQ.php
** Bannerman, Robert and Ellen Considine. 2003 Rain Gardens: A How-To Manual for Homeowners. Univ of Wisconsin Extension. Learningstore.uwex.edu/assets/pdfs