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Stormwater Management Plan

Stormwater is water from precipitation (such as rain or snowmelt), over-irrigation from sprinklers, wash water from hoses or hydrants, or any other water that flows over the ground surface and enters a drainage way. This water picks up debris, sediment, nutrients, bacteria, and other pollutants that eventually flow, untreated, into creeks, streams and rivers. Impervious surfaces such as sidewalks, driveways, rooftops, and streets prevent storm water from soaking into the ground and therefore produce runoff.

Mission Statement

To protect the quality and quantity of stormwater runoff entering Rapid Creek, Canyon Lake, Box Elder Creek, Roosevelt Pond, Lime Creek, the Cement Plant Pond and all tributaries, resulting from Rapid City's urban growth. The City will accomplish this mission through public education and participation; illicit discharge detection and elimination; construction site and post-construction site runoff controls; and improved pollution prevention and good housekeeping within all city operations.

Since 1972, the Clean Water Act and its amendments have prohibited the discharge of any pollutant to a water of the United States unless it has been authorized by a national pollutant discharge elimination system (NPDES) permit. The NPDES program is designed to track point sources (single identifiable sources that discharge pollutants into the environment) and require the implementation of controls necessary to minimize the discharge of pollutants.

The NPDES program initially targeted easily detected sources of water pollution such as municipal sewage and industrial process wastewater and was successful in improving water quality. However, the NPDES program was not addressing stormwater runoff. The Clean Water Act was amended in 1987 to address the environmental impact of stormwater by adding section 402(p), which established a two-phase approach to stormwater control.

Phase I was promulgated on November 16, 1990. Phase I required medium and large (serving populations of 100,000 or greater) municipal separate storm sewer systems (MS4s) to obtain NPDES permit coverage. An MS4 is defined as a conveyance or system of conveyances (including storm drains, pipes, ditches, etc.) that is owned by a public entity and that discharges to waters of the United States.

Phase II was promulgated on December 8, 1999. Phase II expanded the scope of the NPDES program to require small municipal separate storm sewer systems (MS4s) to obtain NPDES permit coverage. A small MS4 is a separate storm sewer system that is operated by a local government and serves a population of less than 100,000.

The City of Rapid City is categorized as a small MS4.In South Dakota, the Department of Environment and Natural Resources (SDDENR) is authorized to run the NPDES program. On March 7, 2003, the City of Rapid City submitted a Notice of Intent (NOI) as required by the Phase II Stormwater Regulations and was issued a General Permit from SDDENR on April 25, 2003.

As part of the General Permit, the City of Rapid City is required to develop and implement a Stormwater Management Plan. The plan must address and implement the following control measures: