E5: San Francisquito Creek Flood Protection*

Flooding History

San Francisquito Creek can cause severe flood damage with very little warning and has overflowed eight times since 1910, including during the December 31, 2022, storm event.

During the February 1998 El Niño event, record flooding caused an estimated $28 million in damages in Palo Alto, East Palo Alto, and Menlo Park. More than 1,100 homes were flooded in Palo Alto, and Highway 101 was closed, as were numerous other roadways. The largest flood on record before 1998 occurred in December of 1955 when the creek overtopped its banks in several locations, inundating about 1,200 acres of commercial and residential property. Damages were estimated at nearly $2 million in 1956 dollars. Total damages from a 1% flood event are estimated at $300 million in Santa Clara and San Mateo Counties, as calculated by the U.S. Army Corps of Engineers (USACE) in 2011.

Project Background

After a serious flooding event in 1998, the San Francisquito Creek Joint Powers Authority (SFCJPA) was formed in 1999 to lead projects that mitigate the risk of flooding along San Francisquito Creek and the Bay. The cities of East Palo Alto, Palo Alto, Menlo Park, the San Mateo County Flooding and Sea Level Resiliency District, and Valley Water formed the SFCJPA.

The San Francisquito Creek Flood Protection Project was initially part of the voter-approved Clean, Safe Creeks and Natural Flood Protection Plan (CSC Plan) that came into effect in Fiscal Year 2001-2002 (FY02). The project aimed to plan and design a project to protect 3,000 homes and businesses from a 1% flood event along the San Francisquito Creek, spanning from San Francisco Bay to Searsville Dam.

Due to a lack of federal funding, on March 27, 2012, the Valley Water Board directed staff to make project changes to ensure that Valley Water met the program commitment of completing planning and design. Valley Water completed a Planning Study Report and proceeded with the design of the project. To comply with the new Civil Works guidance for feasibility studies, the USACE held a planning charette in August 2013, resulting in rescoping the project to focus on Reach 2 (Highway 101 to El Camino Real) for a  flood risk management project only.

Voters Approve 2012 Safe, Clean Water Program

In November 2012, voters approved the Safe, Clean Water and Natural Flood Protection Program (2012 Program), which replaced the CSC Plan. The project was carried forward into the 2012 Program with two new key performance indicators (KPIs). The preferred project with federal and local funding entailed providing 1% flood protection to more than 3,000 parcels. The local-funding-only project focused on protecting approximately 3,000 parcels from flooding (100-year or 1% protection downstream of Highway 101 and 50-year protection upstream of Highway 101.)

In 2014, the Valley Water Board modified the project due to lack of federal funding and the availability of insufficient state and local funding in the foreseeable future. Downstream of Highway 101, the preferred project remained the same, while upstream modifications focused on channel capacity and bridge adjustments to handle floodwaters up to 7,000 cubic feet per second (cfs), equivalent to a 30-year flood event. This modification aimed to protect approximately 3,000 parcels in Palo Alto. If additional funding were to become available, further enhancements for a 1% (100-year) flood protection project upstream of Highway 101 could be considered. Details about the modification can be found at https://www.valleywater.org/sites/default/files/SCW_Public%20Hearing%20on%20San%20Francisquito.pdf.

In 2019, Valley Water completed the construction of the San Francisco Bay to Highway 101 reach of the project to provide 1% flood protection and ecosystem benefits to the neighboring communities. Major improvements included the construction of approximately 4,000 feet of floodwall and the creation of a significantly wider creek marsh plain. The completion of this stretch protects approximately 3,000 parcels in Palo Alto from a flood event close to the February 1998 flood, the largest on record.

Voters Approve the Renewed Safe, Clean Water Program

In November 2020, voters approved the renewed Safe, Clean Water and Natural Flood Protection Program, replacing the 2012 Program. The project has continued in the renewed Safe, Clean Water Program.

About the Safe, Clean Water and Natural Flood Protection Program

In November 2020, voters in Santa Clara County overwhelmingly approved Measure S, a renewal of Valley Water’s Safe, Clean Water and Natural Flood Protection Program.

The program was first passed by voters in 2000 as the Clean, Safe Creeks and Natural Flood Protection Plan, then again in 2012 as the Safe, Clean Water and Natural Flood Protection Program. The renewal of the Safe, Clean Water Program will continue to provide approximately $47 million annually for local projects that deliver safe, clean water, natural flood protection, and environmental stewardship to all the communities we serve in Santa Clara County.

While evaluating ways to improve the 2012 program, Valley Water gathered feedback from more than 21,000 community members. That helped Valley Water create the six priorities for the renewed Safe, Clean Water Program, which are:

Priority A: Ensure a Safe, Reliable Water Supply

Priority B: Reduce Toxins, Hazards and Contaminants in our Waterways

Priority C: Protect our Water Supply and Dams from Earthquakes and Other Natural Disasters

Priority D: Restore Wildlife Habitat and Provide Open Space

Priority E: Provide Flood Protection to Homes, Businesses, Schools, Streets and Highways

Priority F: Support Public Health and Public Safety for Our Community

Each year, Valley Water prepares a report providing a progress update for each of these program priorities, along with fiscal year accomplishments.

To ensure transparency and accountability to the voters, the ballot measure also created an Independent Monitoring Committee, appointed by the Santa Clara Valley Water District Board of Directors. The Independent Monitoring Committee annually reviews the program’s progress to ensure the outcomes are achieved in a cost-efficient manner and reports its findings to the Board. Additionally, the IMC also reviews each proposed 5-year implementation plan prior to its submittal for Board approval.

In addition, the program requires three independent audits.

View the Safe, Clean Water Program’s annual reports, annual IMC audit reports, and independent audits, including a staff response, on the Valley Water website.