Gilroy, CA Environmental Rules: Stormwater Management (2026)

Chapter 27C, Municipal Storm Water Quality Protection and Discharge Control, implements the federal Clean Water Act and the state Porter-Cologne Water Quality Control Act locally. Section 27C.7's illegal discharge prohibition is broad by design: it reaches any material that causes or contributes to a water quality standard violation, regardless of whether that specific pollutant is separately listed in the chapter. Section 27C.8 fills in a long list of named illegal discharges from commercial and industrial sources, including gas station and vehicle-service wash water, auto body shop rinse water, dumpster leakage, pressure-washing runoff from outdoor surfaces, concrete truck washout, and swimming pool or spa water.

Certain low-risk flows are exempted from the illegal-discharge label under Section 27C.7(a), such as potable water line flushing, uncontaminated groundwater, diverted stream flows, air conditioning condensation, and firefighting flows, so long as they are properly managed and not separately found to violate the Porter-Cologne Act, Clean Water Act, or the chapter itself. The director of public works administers the chapter and, on finding a violation, issues a written notice of violation under Section 27C.28 that can require monitoring, cessation of the discharge, remediation, restoration of affected property, and payment of costs.

A recipient has five days to appeal that notice to the city administrator under Section 27C.29, with a hearing held within 15 days of the appeal. If a violation is not corrected as ordered, the city may enter the property and abate it itself under Section 27C.30, then bill the owner for the cost under Section 27C.31, subject to a 15-day written protest to the city clerk and a public hearing before the city council.