Stormwater runoff is any water that is not soaked into the ground after a rain storm.

Consequently, stormwater runoff can pick up pollutants while flowing into local streams and rivers. The Stormwater Management Program (SWMP), launched in 2003, is ODOT's inter-agency effort to control pollutants in storm water discharge. By unifying a cross section of ODOT programs, such as training, planning, maintenance, construction and facilities management with a common focus on water quality issues, ODOT complies with the Clean Water Act requirements administered by the Ohio EPA while reducing pollutants from Ohio's storm sewer system.

ODOT created the SWMP in response to being regulated as a Municipal Separate Storm Sewer System (MS4). The MS4 designation invokes federal legislation that mandates all municipalities reduce the quantity of pollutants from stormwater runoff.