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About the Practice

Bioswales are installed as an alternative to underground storm sewers and consist of vegetation that is usually native prairie species, permeable soil, a perforated subdrain, and berms. A bioswale is engineered to treat runoff from a 1.25" rainfall event and conveys larger rainfall events.

Bioswales differ from biocells in that they are in sloped areas so that when larger storms occur they are safely conveyed to flood management practices such as constructed wetlands, retention or detention basins before draining into the nearest stream or waterbody. It is critical that bioswales are inspected and maintained periodically to ensure their continued performance.

The Iowa Storm Water Management Manual provides design guidance and specifications.