A rain garden is a planted depression that allows rainwater runoff from impervious urban areas like roofs, driveways, walkways, parking lots, and compacted lawn areas the opportunity to be absorbed. This reduces rain runoff by allowing stormwater to soak into the ground (as opposed to flowing into storm drains and surface waters which causes erosion, water pollution, flooding, and diminished groundwater). They can be designed for specific soils and climates. Rain gardens can cut down on the amount of pollution reaching creeks and streams by up to 30%.
Native plants are recommended for rain gardens because they generally don’t require fertilizer and are more tolerant of one’s local climate, soil, and water conditions, and attract local wildlife such as native birds. The plants — a selection of wetland edge vegetation, such as wildflowers, sedges, rushes, ferns, shrubs and small trees — take up excess water flowing into the rain garden. Water filters through soil layers before entering the groundwater system.