The term "rain garden" refers to a constructed depressional area that is used as a
landscape tool to improve water quality. By providing infiltration and water storage for stormwater
runoff, rain gardens minimize the volume and improve the quality of runoff entering conventional
storm drains and nearby streams. Rain gardens should be placed strategically to intercept the
"first flush" of runoff, which contains the highest concentration of pollutants from impervious
surfaces. Once runoff is ponded in the rain garden, organic matter and soil particles will remove
pollutants, and vegetation will remove nutrients. In size, the rain garden should be 5% of the area
drained, and it should contain the following components: a grass buffer strip, a ponding area,
planting soil, a mulch/organic layer, and riparian plants.
