A swale is a grassy depression that controls stormwater velocity and infiltrates runoff where feasible. Swales are typically used to channel stormwater from a street or sidewalk to a rain garden or basin.

A stormwater swale at Womrath Park

Stormwater swales are vegetated channels that transport stormwater runoff. Swales are typically designed to control stormwater runoff velocity and infiltrate it where feasible.The systems are often used as pretreatment for another downstream stormwater tool, such as a rain garden or stormwater basin. They’re most often planted with turf grass and maintained as lawn areas. Stormwater swales may be located adjacent to roadways and parking lots, upstream of other stormwater tools, or in areas prone to overland flooding.

Diagram of a stormwater swale
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