Lush green willows overhang the banks of the San Francisquito Creek. Credit: Len Materman.
Project Documents
Independent Review HEC-RAS Model, 2024
Valley Water’s Final Draft Technical Memoranda on Stream Hydrology, June 2023.
Project Description, Draft Arborist Report, and Plan Set for Pope-Chaucer Bridge, as provided to Palo Alto, Menlo Park and East Palo Alto, August 2020.
Menlo Park Heritage Tree Permit Application April, 2021
Preliminary Arborist Report, April 2021
Revised Preliminary Arborist Report, April 15, 2021
Final EIR Upstream of Highway 101 - Volume 1. September 2019
Final EIR Upstream of Highway 101 - Volume 2 Appendices A - E. September 2019
Final EIR Upstream of Highway 101 - Volume 2 Appendices F - G. September 2019
The Reach 2 - The “Upstream” or “Urban Reach” Project.
The SFCJPA’s projects use the term “Reach” to describe a specific segment of the San Francisquito Creek, or the Bay shoreline. In the case of the Reach 2 project, this describes the area of the Creek from where Middlefield crosses the creek, downstream to where Highway 101 crosses the creek.
The SFCJPA is the lead agency under the California Environmental Quality Act (CEQA) and has certified an Environmental Impact Report (EIR) for the Reach 2 “urban” project between Middlefield Road and Highway 101. The SFCJPA is also the lead for regulatory permitting for the project elements in this reach.
Better instrumentation and technology was in place on 12/31/2022 than during the 1998 flood. The recent storm and resulting overtopping of the creek’s banks on 12/31/2022 provided a great deal of data about how the watershed and the creek behave during intense storms that was not previously available. This will help to re-calibrate the hydraulic model of the creek and adjust project planning accordingly.
For example, prior to the 2022 flood it was widely believed that the Pope-Chaucer bridge was the primary location of overbanking in this reach, but the creek overbanked at several locations downstream of the bridge. This new information suggests that modifications to the bridge will require larger than previously believed changes to the planned channel and bank-top work downstream. The 2022 flood also demonstrated that changing weather patterns can have greater impacts over a short duration. This suggests that our project planning should consider providing immediate flood risk reduction as well as long term changes to reduce flood hazard exposures.
The Reach 2 project as currently proposed consists of four components, each of which have independent utility but together provide for greater flood risk reduction and ecosystem restoration. Working from downstream to upstream, they include:
Replace Newell Road Bridge
Widen the channel at strategic locations
Repair or replace existing top-of-bank floodwalls
Replace Pope-Chaucer Bridge
NEWELL ROAD BRIDGE
Lead: Caltrans, City of Palo Alto
The City of Palo Alto is leading the replacement of the Newell Road Bridge. Funded by Caltrans and Valley Water, the existing 1911 bridge, which has been categorized as functionally obsolete, will be replaced with a modern bridge that will improve traffic safety and allow for greater creek flow conveyance.
Construction Cost: $15.5 Million
Status: Construction anticipated 2024
Newell Road/San Francisquito Creek Bridge Replacement Project – City of Palo Alto, CA
Project information from a presentation given by Palo Alto staff to East Palo Alto City Council on June 19, 2019 https://www.cityofpaloalto.org/files/assets/public/public-works/engineering-services/webpages/pe-12011-newell-road-san-francisquito-creek-bridge/19_0619-pwtc-newell-road-bridge-cpa-presentation.pdf
CHANNEL WIDENING
Lead: US Army Corps of Engineers (USACE)
The Corps of Engineers is undertaking a Continuing Authorities Program (CAP) Section 205 study for the widening of strategic locations along the channel between Pope-Chaucer Bridge and Highway 101. The creek currently floods at these constriction points and would flood to a greater extent when more flow is allowed to flow down the channel if not modified. Vertical sheet piles will be installed where space is limited for widening. In locations with more space to work, the bank will be laid back to a stable slope and vegetated with native species. Acquisition of temporary and permanent easements from private property owners will be required prior to construction.
Construction Cost: $14.5 Million
Status: Construction anticipated 2025
The channel widening element of the project may be split in two parts. This option is being evaluated. If analysis shows doing this will enable acceleration of the project, the SFCJPA will lead on part, and the USACE will lead on the other.
TOP-OF-BANK FLOODWALLS
Lead: SFCJPA
Aging floodwalls are present along much of the top of the creek banks on both sides of the creek downstream of Newell Road. These structures must be replaced before additional flows are able to be conveyed through the channel because upstream constrictions have been removed. Construction Cost Estimate: $10 Million Status: Construction anticipated 2025
POPE-CHAUCER BRIDGE
Lead: SFCJPA
The Pope-Chaucer Bridge has an undersized culvert that backs up flow in large events and causes overtopping upstream of the bridge. The bridge will be replaced or modified to reduce flood risk upstream. Project elements downstream of the bridge will need to be completed first to prevent a transfer of risk. Construction Cost: $17 Million
Status: Construction anticipated 2026
Page updated on April 2, 2024
Rough sketch map of the Reach 2 Project elements.
FREQUENTLY ASKED QUESTIONS
Frequently Asked Questions (updated March 2024)
What has been learned about the creek after the winter storms and flooding of 2022/2023?
The SFCJPA’s member agency, Valley Water, performed a detailed analysis of the creek’s behavior to understand why observed events did not correlate well with predicted results from the hydraulic model (HEC-RAS model). This model was used as the basis of design for the proposed Reach 2 Project components. This evaluation determined that the creek capacity was underestimated in the model- and that observed water surface elevations were up to two feet higher than predicted (Valley Water, June 2023).
The SFCJPA commissioned an independent evaluation of the HEC-RAS model, as well as an updated survey of the channel at locations of observed creek overtopping from the New Year’s Eve 2022 flood event. We also asked our consultant to review the USGS methodology of validating data at their stream gage in San Francisquito Creek located in Stanford’s Golf Course. The full analysis and evaluation can be found on the SFCJPA website: https://www.sfcjpa.org/s/Independent_Review_RASModelUpdateReport_02282024.pdf
The New Year’s Eve 2022 event was the second highest flow in recorded history. During previous flood events monitoring instrumentation, observations, and flow models were not as detailed or complete as we have now. We learned that:
· An updated flood frequency analysis indicates that the New Years’ Eve storm was approximately a ‘30-year’ event.
· The channel has approximately 25% less capacity than we thought it had.
· We always understood that the Pope/Chaucer Bridge is a choke point and water spills upstream of the bridge – BUT - it also prevents a lot of trouble by restricting flow downstream, protecting certain areas of Menlo Park and East Palo Alto. So, we must be very careful with this part of the project to avoid making a bigger problem somewhere else (It is against the law to transfer risk.)
Is Stanford University’s Searsville Dam responsible for the flooding?
No. There have been rumors and inaccurate information circulating that Stanford has already removed the Searsville Dam, causing sediment or high flows during storms, that have caused flooding. This is wrong. Stanford University is considering how best to restore fish passage by creating a hole in the Searsville Dam. They are still working on their environmental analysis. The Searsville Dam is still in place. Nothing has changed. You can learn more about Stanford’s proposed project on their project website here: https://searsville.stanford.edu/
What about sediment from behind the dam? Will that cause a problem?
The potential exists for sediment that has accumulated behind the dam to reduce creek capacity downstream once the Searsville project is built. However, Stanford must mitigate sediment impacts as part of their project. Stanford has already built plans for sediment traps in the upper watershed into their design.
Was flooding caused by overgrown vegetation?
No. Valley Water’s evaluation indicates that even if aggressively managed, removing vegetation will not be the solution to prevent flooding on the San Francisquito Creek. This was corroborated by the Independent Review.
The SFJCPA is drafting an invasive species management plan to help address some of the over-growth and this will help a little bit to maintain creek habitat and capacity - but vegetation is neither the cause of nor is its removal a solution to flooding along the creek.
Why doesn’t the SFCJPA fix the issues with the trees and erosion everywhere?
The rights, and rules, of private property ownership limit what public agencies can do. Access to the creek is limited by a patchwork of private ownership and access easements with cities, counties, and other agencies. Typically, those easements are only for specific purposes, such as flood control feature maintenance.
A useful guide to creek bank restoration and maintenance, “The San Francisquito Creek Bank Stabilization and Revegetation Master Plan” is available on the SFCJPA website https://www.sfcjpa.org/jpa-documents-archives.
Can upstream detention solve the flooding problem?
Not as a stand-alone action - we must do what we can downstream first. We have some preliminary information about costs, and how we might design and build such a project. As we consider approaches and options for increasing flood protection, this may be explored in more detail.