Special Notice / Hearing: None__
Vote Required: Majority
To: Honorable Board of Supervisors
From: Jasneet W. Sharma, Director, Sustainability Department
Subject: Introduction of an Ordinance Repealing Chapter 4.100 of the San Mateo County Ordinance Code, Storm Water Management and Discharge Control, and Replacing it with Chapter 4.100 Stormwater Pollution Prevention
RECOMMENDATION:
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Introduction of an ordinance repealing Chapter 4.100 of Title 4 of the San Mateo County Ordinance Code, Storm Water Management and Discharge Control, and replacing it with Chapter 4.100 Stormwater Pollution Prevention, determining that the ordinance is exempt from the California Environmental Quality Act (“CEQA”), and waive the reading of the ordinance in its entirety.
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BACKGROUND:
The Stormwater Pollution Prevention Ordinance (Ordinance) applies to unincorporated areas of the county to implement the state-mandated Municipal Regional Stormwater National Pollutant Discharge Elimination System (NPDES) program. The NPDES program protects and enhances water quality by reducing pollutants and eliminating non-stormwater discharges such as fluids, debris and waste into county storm drain systems, watercourses and waterbodies, including creeks, the Bay, and the ocean. As a permittee, the County is subject to a NPDES state program and the permit issued by the San Francisco Bay Regional Water Quality Control Board (Regional Water Board). In addition to NPDES permit provision requirements, the County is mandated by the Regional Water Board to monitor and improve water quality in five watersheds: Pillar Point Harbor and Venice Beach, Pescadero-Butano, San Gregorio, San Vicente Creek, and San Pedro Creek and Pacifica State Beach.
On February 14, 1995, the Board adopted the Storm Water Management and Discharge Control Ordinance (Ordinance No. 3633) providing the authority for the County to implement the federal Clean Water Act in the unincorporated county area. Periodic updates have occurred with responsibility for administration and enforcement held by the County’s Environmental Health Services Division.
On May 11, 2022, the Regional Water Board revised and reissued the NPDES permit expanding local jurisdiction stormwater pollution prevention management requirements including, but not limited to, increased trash control requirements, lower impervious surface thresholds for private development projects, and annual capital cost reporting. These changes necessitate a comprehensive overhaul of the existing Ordinance.
DISCUSSION:
The primary purpose of the revised Ordinance for unincorporated areas of the county is twofold:
1. To reduce the entry of pollutant discharges from industrial, commercial, agricultural, and municipal operations into county storm drain systems, watercourses, and waterbodies.
2. To treat stormwater locally for pollutants with strategies such as retention basins or permeable surfaces in private developments.
The Ordinance differentiates stormwater quality management from flood prevention and management strategies, focusing on pollution prevention that is mandated through the NPDES program rather than flood control.
This revision is a collaborative effort between the Sustainability Department, Department of Public Works, Planning and Building Department, Parks Department, and Environmental Health Services Division to:
1. Align with current state mandates.
2. Provide authority to the County to implement and enforce new permit provisions to meet state mandates.
3. Reflect the shared roles and responsibilities undertaken by departments to implement and enforce this Ordinance.
Consultation and outreach on the ordinance were conducted with the California Coastal Commission confirming no Local Coastal Program amendment is required, and through presentations before the MidCoast Community Council, Pescadero Municipal Advisory Council, North Fair Oaks Community Council, and Planning Commission. No comments or modifications were requested by these Councils or Commissions.
Roles and Responsibilities
Under the updated Ordinance, the County gains enhanced legal authority for pollution prevention implementation and enforcement to meet state mandates through various departmental roles such as:
• Sustainability Department: Facilitates cross-departmental stormwater coordination and annual reporting.
• Planning and Building Department: Oversees erosion and sediment control review of private and public development projects.
• Department of Public Works: Installs trash capture devices within County-maintained road rights-of-way.
• Environmental Health Services Division: Conducts industrial and commercial site inspections and manages illicit discharge response.
• Parks Department: Installs and maintains pollution control measures in County parks.
Summary of Ordinance Changes
A summary of key Ordinance changes include:
• New and refined definitions for regulatory clarity. Definitions include Area of Special Biological Significance and expansion of Authorized Enforcement Official beyond Environmental Health Services to also include Planning and Building, Parks, Public Works, and Sustainability Departments.
• Strengthened departmental roles for seamless stormwater compliance. To reflect the current organizational structure of the County’s stormwater compliance program, responsibility for stormwater management and compliance is shared across multiple departments with the Sustainability Department leading coordination efforts.
• Incorporation of supporting documents by reference to allow for efficient periodic updates. Supporting documents include the County Drainage Manual, Commercial and Industrial Business Inspection Enforcement Response Plan (ERP), Illicit Discharge ERP, and Construction Site Control ERP, among other state and federal regulations.
• Incorporation of new permit provisions for necessary updates. Provisions from the updated NPDES permit, such as trash reduction, have been integrated into the Ordinance ensuring compliance with updated regulatory requirements.
• Legal authority to enforce and ensure ongoing compliance. The updated NPDES permit requires jurisdictions to have the legal authority to enforce provisions. Language has been updated throughout the ordinance to continue to provide authority and clarification, such as authority to stop construction on a site where adequate controls are not in place.
Additionally, the County Drainage Manual and three Stormwater Enforcement Response Plans were updated. These supporting documents help implement the Ordinance by providing guidance to County staff and the public regarding new development, redevelopment, and enforcement. Supporting documents are incorporated by reference rather than direct inclusion, and may be revised as needed by departments without Ordinance revisions.
Implementation through County Projects
The Sustainability Department partners with County Departments and the Cities of Half Moon Bay and Pacifica to meet water quality standards including bacteria, sediment, and trash load reduction. For instance, a large trash capture device and youth education outreach project in North Fair Oaks was completed with the Department of Public Works in summer of 2025 to reduce trash from entering the San Francisco Bay through a U.S. Environmental Protection Agency grant. An additional $1M grant is anticipated in early 2026 for a sediment reduction project in the Pescadero-Butano watershed. Sustainability continues to seek grant funding for implementation projects since this program is an unfunded state mandate.
The County Attorney’s Office has reviewed and approved the ordinance as to form.
ENVIRONMENTAL REVIEW:
Adoption of the proposed ordinance is categorically exempt from the California Environmental Quality Act (CEQA) pursuant to Section 15308 for Actions by Regulatory Agencies for Protection of the Environment.
COMMUNITY IMPACT:
Stormwater pollution prevention is critical in reducing pollutants of concern and protecting water quality for all County residents.
FISCAL IMPACT:
No fiscal impact. Ordinance adoption does not impose new fees or require additional staffing or funding. Funding for implementation projects on County properties will be secured through grant funding.