The multi-jurisdictional authority charged with preventing San Francisquito Creek from overflowing onto city streets is aiming for a consensus on a flood control plan by the end of this year.
The San Francisquito Creek watershed encompasses approximately 45 square miles extending from the Santa Cruz Mountains to San Francisco Bay. The center of the creek lies on the boundaries of the five member cities and agencies of the San Francisquito Creek Joint Powers Authority. They include the cities of East Palo Alto, Palo Alto and Menlo Park, as well as the Santa Clara Valley Water District and the San Mateo County Flood Control District, also known as One Shoreline.
The San Francisquito Creek channel is being reengineered in phases, from the Bay to the mountains. The first span between U.S. Highway 101 and the Bay was completed in 2019.
The second span of the creek, called Reach 2, extends upstream from Highway 101 along the border between San Mateo and Santa Clara counties. The Reach 2 span of the creek rests on an elevated ridge, so water in the channel travels above the urbanized areas.
When floodwater tops the creek, it rushes downhill for miles, sometimes flooding communities nowhere near the creek. It becomes everybody’s problem. The authority’s job is to find everybody’s solution.
What Reach 2 could change
On Tuesday, SFCJPA executive director Margaret Bruce discussed several scenarios with the East Palo Alto City Council. Bruce presented a suite of options for the redesign of Reach 2, including canal widening, building flood barriers, removing obstacles from the creek and reconstructing bridges that are too small to handle the flow rates from increasingly intense storms that come with climate change.
Special focus was directed to the reconstruction of a bridge at the junction of Pope and Chaucer streets. The bridge opening is too small. High waters bottleneck there and overtop the channel, flooding neighborhoods in Palo Alto, East Palo Alto and Menlo Park, as it did on the last day of 2022. But the Pope-Chaucer Bridge is not the only trouble spot. Bruce displayed a map that shows seven locations where the creek is pinched by natural or man-made elements that will need to be removed or rebuilt. The pattern of flooding was represented in pink.
“And, looking at your map with the little fuchsia-colored thing, it looks like a lot of that flooding is coming from that Pope-Chaucer Bridge,” said Councilmember Carlos Romero, noting that 83% of the homes that would be protected by the redesign of the channel lie in East Palo Alto and Palo Alto.
Romero asked Bruce about her perceived willingness of Menlo Park to build flood barriers. The SFCJPA research estimated that just 857 properties in Menlo Park would be protected by redesigning the creek channel, versus 1,252 in East Palo Alto and 2,943 in Palo Alto.
“I don’t know at this moment what Menlo Park would be content with,” said Bruce. “I think our board is committed to working with their board members to make sure that we have a workable project that meets everyone’s needs.”
The next steps include continuing to evaluate alternatives, selecting project components and moving into design, permitting and cost-sharing frameworks, Bruce said.
Funding, timelines and cost
What is the cost estimate?
It is too early to speculate on the real cost of the project, said Bruce, especially after President Donald Trump’s administration canceled funding to cities for disaster-resilient infrastructure projects.
“We have about $8.5 million in a grant from the (state) Department of Water Resources,” said Bruce. “That is not going to be enough to complete it, but it’s a healthy good start.”
Other potential funding sources include $10 million from the U.S. Army Corps of Engineers, depending on the corps’ cost-benefit analysis.
“What’s left over is the part that needs to be divvied up between the beneficiaries,” said Bruce. “Once we count all the parcels that are in all of the flood areas, we can do an assessment of which jurisdictions benefit from which elements of the project.”
Each SFCJPA member contributes an equal amount to the authority’s annual operations budget, which covers regular administration. On Aug. 12, Valley Water approved their portion, $329,097, but it stopped short of approving an additional $604,000 in capital expenditure for the Reach 2 project planning and design. Valley Water will hear the updated SFCJPA presentation at their Sept. 23 meeting before committing the capital contribution.
This is the authority’s second pass at finding an engineering solution for Reach 2. In 2022, there was a finalized design based on digital modeling. Permits were submitted. But on Dec. 31, 2022, a large storm caused the creek to flood in unexpected ways and overflow into the Woodland Avenue area of East Palo Alto.
“We thought the creek channel had more capacity than it actually does,” said Bruce in a conversation before Tuesday’s meeting. “Our project designs went from being sufficient to being 25% insufficient literally overnight.”
Lessons from 1998 and 2022
The only silver lining that came from the 2022 flood is that it generated real-world data for design engineers to use, rather than a computer-generated projection.
The SFCJPA was created in 1999, following a devastating flood in 1998 that damaged hundreds of homes. Approximately 70,200 cubic feet of water per second rushed down the creek and overflowed at the pinch points in the channel. That 1998 event was considered a 70-year storm, which means there is a 1-in-70 chance of a storm that size occurring in a given year, or about a 1.4% chance.
As the largest “flood of record,” bigger than the 2022 storm, the data from the 1998 flood is being used as a guide to design fixes for Reach 2.
“You’re assuming that you’re going to get to a preferred alternative by the end of this year that would require bringing all partners to the table?” Romero said.
“I would say, going back to one of my favorite catchphrases, we live in an infinite universe as far as the human experience,” said Bruce. “Therefore, in theory, there are an infinite number of possible solutions. We just have to find the right ones.”