Storm Water

Storm Water System


The storm sewer system refers to important infrastructure that prevents flooding when it rains. The system, also known as a Municipal Separate Storm Sewer System or MS4, works to move water away from an area to a local water body, such as a creek or river. The storm sewer system includes the inlets (storm drains) and gutters on your street as well as pipes and outfalls, where the storm water enters the water body. Because the MS4 flows directly into water bodies without any treatment it is critical to keep it pollutant free.

The City's storm drain system includes over 75 miles of open channels/ditches, over 320 miles of public underground pipes, and over 18,000 structures representing over $200 million in storm drain infrastructure investment.

To protect residents and our local creeks the Storm Water Team monitors water quality to assess local creeks and focus on local pollutants of concern including elevated temperatures, sediment, and bacteria. Monitoring includes chemical and biological sampling during storm events and the low flow season. Chemical monitoring provides concentrations of constituents while biological tests show the response of actual living organisms to creek samples or conditions.

Review our NPDES Permit Annual Report (PDF) for sampling results.

Permits & Regulations


The work the City of Santa Rosa does to prevent storm water pollution is regulated under the jurisdiction of the North Coast Regional Water Quality Control Board (Regional Board), the enforcement arm of the State Water Resources Control Board (Water Board).

The Regional Board issues a National Pollutant Discharge Elimination (NPDES) Storm Water Permit (PDF) jointly to the City of Santa Rosa, County of Sonoma and the Sonoma County Water Agency. The permit governs a variety of activities in the City of Santa Rosa such as industrial and commercial businesses, new and redevelopment projects, construction sites, storm drain operation and maintenance, creek monitoring, pesticide applications, and illegal dumping of water and other pollution in the City's storm drain. Visit our pollution prevention page for more information.

The City enacted a storm water ordinance (Ordinance No. 3272) on July 30, 1996 to obtain legal authority needed to implement the provisions contained in the NPDES permit for storm water discharges.

Annual Report


Under the permit, Santa Rosa has a Storm Water Management Plan outlining proposed activities necessary to protect our creeks and rivers from polluted storm water runoff. The City also prepares an Annual Report (PDF) that evaluates progress during that fiscal year. Both documents are approved by the City Council prior to their submittal to the Regional Board.