Municipal Phase I Program
The Municipal Storm Water Permitting Program regulates storm water discharges from municipal separate storm sewer systems (MS4s). Storm water is runoff from rain or snow melt that runs off surfaces such as rooftops, paved streets, highways or parking lots and can carry with it pollutants such as: oil, pesticides, herbicides, sediment, trash, bacteria and metals. The runoff can then drain directly into a local stream, lake or bay. Often, the runoff drains into storm drains which eventually drain untreated into a local waterbody.
Additionally, municipal or urban areas commonly include large impervious surfaces which contribute to an increase in runoff flow, velocity and volume. As a result, streams are hydrologically impacted through streambed and channel scouring, instream sedimentation and loss of aquatic and riparian habitat. In addition to hydrological impacts, large impervious surfaces contribute to greater pollutant loading, resulting in turbid water, nutrient enrichment, bacterial contamination, and increased temperature and trash.
Under Phase I, which started in 1990, the Regional Water Boards have adopted NPDES storm water permits for medium (serving between 100,000 and 250,000 people) and large (serving 250,000 people) municipalities. Most of these permits are issued to a group of co-permittees encompassing an entire metropolitan area. These permits are reissued as the permits expire. The Regional Water Board has one Phase I Municipal Separate Storm Sewer System (MS4) permit for the Whitewater River Watershed, the permittees include: Riverside County Flood Control and Water Conservation District (RCFC&WCD), Riverside County, Coachella Valley Water District, Cities of Desert Hot Springs, Palm Desert, Banning, Indian Wells, Palm Springs, Cathedral City, Indio, Rancho Mirage, and La Quinta.
Board Order R7-2013-0011 was adopted on June 20, 2013 and is the Phase I MS4 Permit for the Whitewater River Watershed.