CITY OF SAN MATEO
CITY OF SAN MATEO
Agenda Report
City Hall
330 W. 20th Avenue
San Mateo CA 94403
www.cityofsanmateo.org
Agenda Number: 14 Section Name: OLD BUSINESS Account Number: 10-4679 File ID: 26-11524 TO: City Council
FROM: Alex Khojikian, City Manager
PREPARED BY: Public Works Department
MEETING DATE: October 5, 2026
SUBJECT:
Storm Drain Master Plan Update — Adoption
RECOMMENDATION:
Approve a Resolution to adopt the updated Storm Drain Master Plan.
BACKGROUND:
Introduction
This staff report provides a brief summary of the background, findings and recommendations, Council and Commission feedback, and next steps related to the Storm Drain Master Plan (SDMP). The SDMP and appendices are available for the City Council’s review on the following website: https://www.cityofsanmateo.org/4953/Storm-Drain-Master-Plan Background
The City’s storm drain system was last comprehensively evaluated under the 2004 Storm Drain Master Plan, where system improvements were largely limited to levee improvements and coastal flood risk reduction due to a lack of dedicated funding for interior drainage upgrades. The New Year's Eve 2022 storm, an approximately 200-year event that overwhelmed the City's stormwater conveyance system and led to overtopping of San Mateo Creek, demonstrated the need for improvements at the Marina Lagoon Pump Station, and ultimately underscored the need for an updated plan.
In November 2023, following a 2023 property-owner ballot, Council adopted the Community Flood and Storm Protection Fee (Storm Fee), effective Fiscal Year 2024-25. The Storm Fee generates approximately $4 million annually, and this new revenue source enabled the City to commission an update to the SDMP. Following a January 2024 Request for Proposals (RFP), Schaaf & Wheeler (S&W) was selected to update the SDMP.
S&W subsequently collected LiDAR elevation data, conducted a Citywide condition assessment, built a hydraulic and hydrologic model of the City's entire storm drain system, and simulated how the model performs in various storm events.
The model was also used to simulate anticipated 2050 and 2100 climate change impacts. The results of the condition assessment and simulation were used in concert to identify portions of the City’s stormwater infrastructure in need of repair and replacement, as well as identify capacity deficiencies which require either upsizing existing improvements or constructing new projects. S&W worked with City staff to establish a set of criteria to score all identified improvements and generate a prioritized list of capital improvements projects (CIPs).
Findings and Recommendation
The prioritized CIP list includes gravity system capacity projects, creek and channel capacity projects, condition-related projects, and pump station improvement projects. The list includes 138 total projects, of which 11 are categorized as “Very High” priority projects. The “Very High” priority long-term project to address Marina Lagoon Pump Station is estimated as
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$100 million alone. The table below summarizes the prioritized CIP list.
Priority Number of
Projects
Estimated Cost
(in Millions)
Estimated Cost without
Marina Lagoon Pump
Station (in Millions)
Very High 11 $148.3 $48.3
High 34 $25.3 $25.3
Medium 35 $26.6 $26.6
Low 58 $24.3 $24.3
Total 138 $224.5 $124.5
S&W additionally evaluated the potential effects of climate change and estimated that addressing projected conditions in 2050 and 2100 could add approximately $30 million to $50 million to the estimated CIP cost, either by incorporating additional resiliency measures into existing or proposed projects or by implementing new projects altogether.
Potential Funding Sources
The very high-priority capital improvement projects, excluding the Marina Lagoon Pump Station long-term improvements, total $48.3 million. With currently available funding, it is anticipated that these projects can be delivered within 15 years.
As the stormwater program develops, staff will pursue multiple funding sources, including internal funding sources discussed below, as well as federal and state grant opportunities and partnerships.
The City has reviewed potential funding options to accelerate delivery of the very high-priority projects and is considering a combination of funding sources based on project size, timing, and available resources. Bond financing was evaluated as one potential option; however, current market conditions are not favorable for issuing bonds at this time. The City may also evaluate an interfund loan from the Sewer Enterprise Fund, which could provide access to borrowing capacity at a lower cost than external financing.
For smaller projects, the City will utilize storm drainage fee revenues to self-fund improvements, with a current fund balance of approximately $2.6M and an additional $2-3 million annually available for capital projects. The 42nd Avenue (4000 Pacific) pump station improvements are anticipated to be an initial example of this approach.
For the Marina Lagoon Pump Station long-term improvements, however, the scale of the project, currently estimated at approximately $100M, exceeds the City's ability to self-fund through the storm drainage fee at this time. Significant federal and other outside funding will therefore be necessary to advance this critical project.
S&W recommends that the 11 “Very High” priority projects be completed over the next ten years.
Improvement Project Project Type Score Cost Improvement Type Marina Lagoon PS - Short-term Pump Station 88 $7,250,000 Maintain Reliability Marina Lagoon PS - Long-term Pump Station 82 $100,000,000 Increase Capacity - Climate Resiliency 4000 Pacific PS - Long-term Pump Station 70 $3,680,000 Increase Capacity 4000 Pacific PS - Short-term Pump Station 66 $960,000 Maintain Reliability Laurel Creek - Curtiss Bypass Creeks 64 $4,650,000 Flood Reduction - FIRM Revision 16th Avenue Channel – Hwy 101 Creeks 62 $23,400,000 Increase Capacity Grant at Sunnybrae Pipes 58 $430,000 Increase Capacity
Newbridge Ave Pipes 58 $2,250,000 Replacing Damaged Assets 42nd Ave Underpass Pipes 56 $230,000 Increase Capacity
Bettina-Kingridge Pipes 50 $647,000 Replacing Damaged Assets Norton Street Pipes 48 $4,800,000 Increase Capacity - Reduce Maintenance
CITY OF SAN MATEO
The CIP listed in the Very High Priority projects typical fall under 4 types of general improvements, with the exception of Laurel Creek – Curtiss Bypass project.
• Maintain Reliability – These projects are typically associated with pump stations, as demonstrated by the Marina Lagoon and 42nd Avenue Pump Station short-term projects. They primarily focus on repairing existing equipment, modifying existing structures, and extending the useful life of the asset until long-term improvements can be implemented.
• Increase Capacity – These projects are associated with increasing storm flow capacity and allowing the system to better accommodate upstream drainage. In the case of the “very high” priority projects, these projects typically rank higher because they are connected to several upstream projects within the system. Improvements at these locations allow future upstream improvements to be implemented and provide the necessary capacity to convey additional flows.
• Replace Damaged Assets – These projects were identified through City-specific site and field investigations, including CCTV inspections using remotely operated systems to identify structural or maintenance deficiencies.
These projects do not necessarily increase system capacity but require replacement of existing pipelines due to years of deterioration.
The Laurel Creek – Curtiss Bypass project is unique because it provides flood reduction benefits while also providing the additional benefit of potentially reducing and/or removing properties from the Special Flood Hazard Area (SFHA), as designated by the Federal Emergency Management Agency (FEMA).
Council and Commission Feedback / Public Engagement
Staff presented the preliminary findings and recommendations from the SDMP to the Sustainability and Infrastructure (S&I) Commission and to City Council in January 2026. On January 14, 2026, the S&I Commission supported continuing investment in projects to address local ponding and requested additional public engagement.
On January 26, 2026, City Council supported the prioritization framework and concurred that the Marina Lagoon Pump Station should be treated as a standalone project given its cost and complexity. City Council further supported exploring financing strategies and requested additional details at a future Council date and supported maintaining $250,000 annual allocation for localized flooding projects. Additional information about funding and financing strategies has been added to Chapter 8 of the SDMP. Both S&I Commission and City Council supported strengthening stormwater management requirements for private developments and directed staff to keep the stormwater mapping tool available long-term to support continued public engagement.
Based on S&I Commission and City Council feedback, staff augmented public engagement efforts. Staff organized an additional community meeting for a total of three community meetings and also published a stormwater mapping tool.
While the community meetings were not strongly attended, the stormwater mapping tool generated over 50 reports.
These reports were used to validate the simulated results from the hydraulic and hydrologic model. The mapping will also be maintained beyond adoption of the SDMP. Locations identified through the reporting tool that are not associated with a proposed capital improvement project will be evaluated on a case-by-case basis to determine whether they should be incorporated as separate standalone improvements or included in the City’s annual program.
Next Steps (Following Adoption)
Following adoption of the SDMP, funding for design and construction for a subset of “Very High” priority projects will be incorporated into upcoming fiscal years. Staff will also continue evaluating supplemental funding and financing mechanisms for “Very High” priority projects, including the long-term Marina Lagoon Pump Station project.
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Staff is already working to procure design consultants to develop plans and construction documents for the 42nd Avenue (4000 Pacific) Pump Station improvements (Projects 2 and 7, below), as well as mainline improvements at Bettina and Kingridge (Project 9) and Grant Street at Sunnybrae (Project 5). To advance implementation of several “Very High” priority projects, the SDMP includes planning-level cost estimates for the following projects in Appendix N:
1. Marina Lagoon Pump Station Improvements
2. 4000 Pacific Pump Station Improvements
3. Laurel Creek – Curtiss Bypass Improvement Project
4. 16th Avenue Channel – Highway 101 Culvert Improvement Projects
5. Grant at Sunnybrae Capacity Improvement Project
6. Newbridge Capacity Improvement Project
7. 42nd Avenue Underpass Improvement Project
8. Norton Street Ditch Improvement Project
9. Bettina Kingridge Rehabilitation and Replacement Project Of these, a subset (4, 5, 6, and 8) include conceptual plans in Appendix O of the SDMP.
Beyond the City’s SDMP update, a major aspect of the City’s flood management efforts has been removing residential properties from FEMA-designated Special Flood Hazard Areas (SFHA). These efforts have focused on providing greater protection for homeowners during 100-year flood events while also reducing the financial burden associated with mandatory flood insurance. This has been an ongoing goal that staff intends to continue as part of the SDMP update.
In previous presentations to City Council and the S&I Commission, staff noted that with more robust data sets and improved engineering models, additional properties could potentially be removed from the flood zone without requiring additional capital investment. Previous discussions identified a handful of properties in and around the Palm Avenue area that could potentially benefit from this effort.
Staff is now pleased to report that additional homes along the Hillsdale Corridor may also be eligible for removal from the FEMA-designated flood zone. Staff is actively working with the design team and consultants to further evaluate and advance this effort. Staff would like to emphasize that these potential flood zone removals are not guaranteed and will be subject to further engineering analysis and FEMA review and approval.
Staff Recommendation
Staff recommends City Council approve the Resolution to adopt the SDMP.
BUDGET IMPACT:
There is no direct fiscal impact associated with adoption of the SDMP itself. The SDMP is a planning document; individual capital improvement projects identified within it will be independently evaluated, budgeted, and brought forward for funding authorization through the City's annual operating and capital budget process, and/or through future financing actions (e.g., inter-fund loan, assessment district, bond issuance, grant award) as applicable.
ENVIRONMENTAL DETERMINATION:
Adoption of the 2026 Storm Drain Master Plan is exempt from the California Environmental Quality Act (CEQA) since it is a feasibility or planning study for possible future actions which the City of San Mateo has not approved, adopted, or funded.
The individual projects in the Plan are not yet funded, and each project will require a separate CEQA analysis at time of design and construction. (CEQA Guidelines Section 15262.) Very high priority and other individual capital improvement projects identified in the SDMP will be required to comply with CEQA prior to implementation. The City will satisfy applicable CEQA requirements through the preparation of the appropriate environmental documentation, such as an Environmental Impact Report (EIR) or Mitigated Negative
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Declaration (MND), unless the project qualifies for a categorical exemption under CEQA.
STRATEGIC PLAN ALIGNMENT
This staff report supports the Infrastructure and Climate Resiliency initiatives.
NOTICE PROVIDED
All meeting noticing requirements were met.
ATTACHMENTS
Att 1 – Proposed Resolution
STAFF CONTACT
James Yang, Senior Engineer
[email protected]
(650) 522-7575