The City of Tucson operates a Municipal Separate Storm Sewer System (MS4), which means the storm drain system is distinct from the sanitary wastewater system. Unlike wastewater, stormwater is not processed at a treatment plant. Instead, stormwater runoff enters our streets and washes, flowing through various parts of the storm drain system. This runoff ultimately reaches regional watercourses, such as Pantano Wash, Rillito Creek, and the Santa Cruz River, where it rapidly recharges our groundwater aquifers.
It is crucial to maintain the cleanliness of our surface water to ensure the purity of our groundwater, particularly in the Tucson area, which is characterized by a high concentration of both private and public drinking water wells. The City of Tucson is governed by the Arizona Pollutant Discharge Elimination System (AzPDES) program, in addition to the City's Stormwater Ordinance.
The Arizona Department of Environmental Quality has prepared a 5-year renewal permit draft for our City of Tucson Municipal Separate Storm Sewer System (MS4). The current 5-year Tucson MS4 permit expires June 30, 2026. You can view the Public Notice at the ADEQ website. Public comment period is open from April 17, 2026 through May 18, 2026.
Tucson City Code, Chapter 26, Floodplain and Erosion Hazard Management
Tucson Code, Chapter 29, Article VIII, Watercourse Amenities, Safety, and Habitat (WASH)
Tucson Code, Chapter 23, Land Use Code (LUC), Article II, Division 8, Section 2.8.6, Environmental Resource Zone (ERZ)
City of Tucson Water Harvesting Guidance Manual, adopted in 2005