Costa Mesa, CA Environmental Rules: Stormwater Management (2026)

Chapter III of Title 8, Water Quality, implements Costa Mesa's NPDES stormwater permit obligations as one of 31 municipal co-permittees with the County of Orange and the Orange County Flood Control District. Section 8-31 flatly bars three things: constructing, maintaining, operating or using any illicit connection to the stormwater drainage system; causing, allowing or facilitating any prohibited discharge; and directing an employee, agent or contractor to do either. The prohibition reaches connections that predate the ordinance too. A pre-existing 'legal nonconforming connection' only stays legal for five years after adoption for structural improvements, or six months after the city sends written notice for nonstructural ones, unless the director of public services grants a reasonable extension after weighing the effect on receiving waters, the discharger's economic investment, and the financial impact of shutting the connection down.

Liability for illicit discharges attaches whether or not the violator acted negligently or intended to cause the discharge (§ 8-31(c)). Beyond the connection ban, Section 8-32 requires every new development and significant redevelopment project in the city, defined to include rehabilitation or reconstruction exceeding 2,000 square feet or half the existing building area, to comply with the Orange County Drainage Area Management Plan and any pollutant-reduction conditions imposed by the development services and public services departments before the city issues a grading permit, building permit, or non-residential plumbing permit.

Single-family detached homes are exempt from Development Project Guidance compliance unless the department finds the construction could discharge a significant pollutant level. Section 8-32 also bans discarding litter or waste material anywhere it can reach a street, gutter, or storm drain inlet.