MS4 Permit

Stormwater and non-stormwater runoff generated within City limits is transported through the municipal separate storm sewer system (MS4), and then discharged, untreated, into local waterbodies such as the Santa Clara River, Ventura River and Pacific Ocean. The City’s MS4  consists of:

  • Roads with drainage systems
  • Municipal streets
  • Catch basin
  • Curbs
  • Gutters
  • Ditches
  • Man-made channels
  • Storm drains

MS4s in Ventura County typically rely upon gravity to move runoff away from urban areas as quickly as possible to reduce flooding and human health and safety risks associated with high water. These systems are owned and maintained by a state, city, town, village or other public entities that discharge to local waterbodies. These systems are not part of a combined sewer system meaning they are not connected to a sewage treatment plant or publically owned treatment works (POTW).

To prevent harmful pollutants from being washed or dumped into the MS4 and ending up in local waterbodies, cities are required to obtain National Pollutant Discharge Elimination System (NPDES) permit coverage and implement programs to reduce and eliminate pollutants from entering the MS4. The Ventura Countywide NPDES MS4 Permit regulates MS4 discharges from City of Ventura, Ventura County Watershed Protection District, County of Ventura and incorporated cities of Camarillo, Fillmore, Moorpark, Ojai, Oxnard, Port Hueneme, Santa Paula, Simi Valley and Thousand Oaks.

The City of Ventura stormwater programs focus on improving, protecting and preserving regional water quality and includes activities such as public outreach and education, business inspections, green building and low impact development strategies, construction site management and illicit connection/discharge elimination. City of Ventura with the other Ventura County MS4 Permittees work together to collectively improve stormwater quality, monitor the health of our watersheds and meet requirements set forth in the Ventura County NPDES MS4 permit. If you are aware of any materials being discharges to storm drains, please call the City of Ventura illicit discharge hotline at (805) 667-6510.

For additional information about the Ventura County MS4 Permit, please visit the Los Angeles Regional Water Quality Control Board stormwater page and the Ventura County MS4 Permit.