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San Francisquito Creek Flood Protection and Ecosystem Restoration Capital Improvement Project East Bayshore Road to San Francisco Bay

Project URL link
Sponsoring Agency San Francisquito Creek Joint Powers Authority
Subregions ('South Bay', 'West Bay')
Counties Santa Clara County, San Mateo County
Watershed Tributary
Public or private land? ()
Location (lat/lon) 37.453139, -122.127270
Start Date 08/01/2015
End Date 12/31/2017
Location Description San Francisquito Creek - San Francisco Bay to Highway 101.
San Francisquito Creek Flood Protection and Ecosystem Restoration Capital Improvement Project East Bayshore Road to San Francisco Bay

The goal of San Francisquito Creek Flood Protection and Ecosystem Restoration Capital Improvement Project, East Bayshore Road to San Francisco Bay is to provide protection against a 1% fluvial event coincident with a 1% tide, with accommodation for 26 inches of projected sea level rise and FEMA freeboard requirements on San Fransciquito Creek between East Bayshore Road and the San Francisco Bay.  If awarded, this grant will fund the removal of abandoned Pacific Gas and Electric pipelines, which is a recently added project component, along with creation of additional marsh habitat.

Drinking Water Supply
Water Quality Improvement
Water Reuse/Recycling
Stormwater Improvements
Groundwater Benefits
Infiltration
Habitat Protection and Restoration
Flood Protection
Water quality benefits attributable to the project include enhanced in-stream water quality and surface water quality protection. The new channel design is expected to result in reduced sedimentation throughout the reach, which will generate a reduction in suspended solids within the reach. The project will completely eliminate flooding through the 100-year fluvial event coincident with the 100-year high tide, taking into account a potential 26-inch rise in sea level over the next 50 years. As such, the project will provide a significant water quality benefit by preventing transport of debris and contaminants from urbanized areas to the San Francisquito Creek during flooding events. The project will create increased tidal marshland habitat (within new channel) at appropriate elevations for intertidal wetland plant and animal species. The project is expected to create approximately 16.1 acres of new or improved Mid-Marsh habitat, and an estimated 4.0 acres of new or improved Low-Marsh habitat. Another benefit will be the restoration of high tide refugial habitat for sensitive wildlife species at the ecotone between tidal wetland and upland habitats. The project will protect more than 1,100 properties from creek flooding, and when coupled with future tidal levee improvements, will remove these properties from the FEMA floodplain. The downstream reach of San Francisquito Creek between East Bayshore Road and San Francisco Bay is at the highest risk of severe flooding in the system, due to undersized channel capacity and sub-standard levees. Flooding risk is exacerbated during high tides. The creek in this area runs through communities that have experienced severe damage during previous flood events, which includes the Disadvantaged Community of East Palo Alto.

Part 2 - Detail

Following years of effort to address environmental issues, and a 45-year flood in 1998 that damaged approximately 1,700 properties, five local agencies from two counties—the cities of Palo Alto, Menlo Park, and East Palo Alto, the County of San Mateo, and the Santa Clara Valley Water District—joined together to create a new regional government agency, the San Francisquito Creek Joint Powers Authority (SFCJPA). The Authority’s multi-jurisdictional approach to solving problems is reflected in this project; which serves to address the interrelated water quality, habitat protection and restoration, and flood protection needs of the region.

The goal of San Francisquito Creek Flood Protection and Ecosystem Restoration Capital Improvement Project, East Bayshore Road to San Francisco Bay (Project) is to provide protection against a 1% fluvial event coincident with a 1% tide, with accommodation for 26 inches of projected sea level rise and FEMA freeboard requirements on San Fransciquito Creek between East Bayshore Road and the San Francisco Bay. 

The project will protect more than 1,100 properties from creek flooding, and when coupled with future tidal levee improvements, will remove these properties from the FEMA floodplain.  The downstream reach of San Francisquito Creek between East Bayshore Road and San Francisco Bay is at the highest risk of severe flooding in the system, due to undersized channel capacity and sub-standard levees.  Flooding risk is exacerbated during high tides.  The creek in this area runs through communities that have experienced severe damage during previous flood events.  The completion of the East Bayshore Road to San Francisco Bay reach is a necessary first step to provide comprehensive flood protection farther upstream. 

The Project will remove fluvial flooding risks from San Francisquito Creek for over 1,000 properties (primary residences) within the City of East Palo Alto.  The Median Household Income in East Palo Alto is $44,000 annually, which is approximately 58% of the Median Household Income (MHI) for the State of California, qualifying East Palo Alto as a Disadvantaged Community (DAC) as defined by the California Department of Finance Population Research Unit. 

The Project would increase stream flow capacity in San Francisquito Creek from the downstream face of East Bayshore Road to San Francisco Bay. It would reduce local flood risks during storm events, as well as provide the capacity needed for upstream flood protection projects being planned by the San Francisquito Creek Joint Powers Authority (SFCSFCJPA).  Increasing the Creek’s flow capacity from San Francisco Bay to Highway 101 would be achieved by widening the Creek channel within the reach to convey peak flows for 100-year storm events, removing abandoned PG&E pipelines, and configuring flood walls in the upper part of the reach for consistency with structure for Caltrans’ enlargement of the Highway 101/East Bayshore Road Bridge over San Francisquito Creek.  Project elements include flood walls, levee setbacks and creek widening in the middle reach between East Palo Alto and the Palo Alto Municipal Golf Course.

The Project addresses ecosystem restoration, flood management, recreation and public access, wetland enhancement and watershed planning. 

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Climate Change: This project will improve marshland resiliency, through improved sediment transport, enhancing shoreline sustainability. By reducing fluvial aggregation and providing a source of sediment to build up high-marsh, the result will be an enhanced marshland resilience, which will combat rising sea levels.   Health of the Bay and Creeks: The project will create increased tidal marshland habitat (within new channel) at appropriate elevations for intertidal wetland plant and animal species. The project is expected to create approximately 16.1 acres of new or improved Mid-Marsh habitat, and an estimated 4.0 acres of new or improved Low-Marsh habitat.  The conversion of low quality floodplain terrace habitat to higher quality marshplain habitat dominated by native tidal salt and brackish marsh species is the key element to the restoration goals of the project. This will be accomplished by increasing the tidal prism, thereby increasing the summertime salinities in the project reach and via the excavation of new marshplains to elevations that will facilitate colonization by tidal salt marsh plant species and deter colonization by ruderal species. Another benefit will be the restoration of high tide refugial habitat for sensitive wildlife species at the ecotone between tidal wetland and upland habitats. This will be accomplished via a combination of grading (e.g. levee lowering and grading of stable inboard levee slopes), topsoil preparation, and active revegetation. Invasive Species Management: The conversion of low quality floodplain terrace habitat (dominated by non-native, perennial pepperweed) to higher quality marshplain habitat dominated by native tidal salt and brackish marsh species is the key element to the restoration goals of the project. This will be accomplished by increasing the tidal prism, thereby increasing the summertime salinities in the project reach and via the excavation of new marshplains to elevations that will facilitate colonization by tidal salt marsh plant species and deter colonization by ruderal species (e.g. perennial pepperweed). Sediment Management: The new channel design is expected to result in reduced sedimentation throughout the reach, which will generate a reduction in suspended solids within the reach resulting in enhanced in-stream water quality.   The project will protect surface water quality by completely eliminate flooding through the 100-year fluvial event coincident with the 100-year high tide, taking into account a potential 26-inch rise in sea level over the next 50 years.  As such, the project will provide a significant water quality benefit by preventing transport of debris and contaminants from urbanized areas to the San Francisquito Creek during flooding events. In addition, sediment transport will be improved throughout the project reach, reducing fluvial aggregation and providing a source of sediment to build up high-marsh. The result will be an enhanced marshland resilience, which will combat rising sea levels.   Riparian and Fisheries Restoration: San Francisquito Creek is unique because it remains one of the only San Francisco Bay streams that is not confined to a concrete channel. As a result, San Francisquito Creek largely retains its natural character despite its urban setting, and is home to many rare and threatened native species, including steelhead trout. The project will result in lower velocity flows during migration season, improving the conditions for the native Steelhead species. 

Residential Flood Damage Assumptions without Project

It is estimated that approximately 703 homes, 914 homes, and 1090 homes would be inundated in the 25-year, 50-year, and 100-year flood, respectively.  In 2011, the total residential damages, including damages to structures and content, was estimated to be $18,655,865, $24,255,278, and $28,925,879 for the 25-, 50-, and 100-year flood events, respectively.  Data related to cleanup and debris removal costs are not available, and have therefore been excluded from this analysis. The majority of residences impacted by this project are located in East Palo Alto, a DAC.

Commercial Flood Damage Assumptions without Project

In 2011, it was estimated that approximately 8 office buildings, 14 office buildings and public facilities, and 18 office buildings and public facilities would be affected in the 25-year, 50-year, and 100-year events, respectively.  In summary, the total commercial damages, including damages to structures and content, is estimated to be $1,216,000, $2,128,000, and $2,736,000 for the 25-, 50-, and 100-year flood events, respectively. 

Road Inundation Damage Assumptions without Project

Costs associated with road inundation were estimated using the default values within the Department of Water Resources’ Flood Rapid Assessment Model.  These default values assume the cost per mile of highway / arterial, major, minor, and unsealed roads to be $250,000, $100,000, $30,000, and $10,000, respectively.  These assumptions are based on estimates developed for the San Francisco Bay Area.  The inundation areas identified in the project area are also located within the San Francisco Bay Area.  As such, it was determined that these values reasonably reflect the costs associated with road inundation in the project area.  In total, these costs sum to $250,000, $330,000, and $475,000 for the 25-year, 50-year, and 100-yaer floods, respectively.

Description of Without-Project Conditions

Under existing conditions, tidal marshland habitat and pickleweed habitat are present but are limited to small spatial in-channel elevations due to accumulated fluvial sediments within the leveed channel throughout the project reach.  The ideal elevation for these habitats is at mean higher high water, or a range between the average daily high tides.  The channel also serves as a migratory corridor for adult and smolt steelhead.  The narrow channel and resulting high velocities limit the opportunity for adult steelhead to pass upstream to spawning areas in the upper watershed during high flow events, the very events that provide for passage upstream of the project reach.

Project Beneficiaries and Distribution of Benefits

This Project will benefit stakeholders at the local and regional levels.  This Project benefits local residents by virtually eliminating the risk of levee overtopping in storm events up to and including the 100-year flood coincident with the 100-year high tide.  In addition, this Project will benefit regional stakeholders by eliminating the risk of flooding to Highway 101.  This Project will provide appreciable statewide benefits by preventing water quality impacts to the San Francisco Bay resulting from flooding.

It is estimated that approximately 703 homes, 914 homes, and 1090 homes would be protected from the 25-year, 50-year, and 100-year flood, respectively. It is estimated that approximately 8 office buildings, 14 office buildings and public facilities, and 18 office buildings and public facilities would be protected from the 25-year, 50-year, and 100-year events, respectively.

Flood Damage Reduction Costs and Benefits

The Project would increase stream flow capacity in San Francisquito Creek from the downstream face of East Bayshore Road to San Francisco Bay. It would reduce local flood risks during storm events, as well as provide the capacity needed for upstream flood protection projects being planned by the San Francisquito Creek Joint Powers Authority (SFCSFCJPA).  Increasing the Creek’s flow capacity from San Francisco Bay to Highway 101 would be achieved by widening the Creek channel within the reach to convey peak flows for 100-year storm events, removing abandoned PG&E pipelines, and configuring flood walls in the upper part of the reach for consistency with structure for Caltrans’ enlargement of the Highway 101/East Bayshore Road Bridge over San Francisquito Creek.  Project elements include flood walls, levee setbacks and creek widening in the middle reach between East Palo Alto and the Palo Alto Municipal Golf Course.

Levee Failure Assumptions With Project

The Project has been designed to prevent flooding in a 100-year fluvial event that coincides with the 100-year high tide, taking into account a potential 26-inch rise in sea level over the next 50 years.  As such, there is zero probability of overtopping during a 25- year, 50-year, or 100-year event.

Description of Expected Water Quality and Other Benefits with Project

The Project will generate significant water quality and ecosystem benefits, including reduced sedimentation, creation of new habitat for sensitive species, and improved recreational opportunities.  These benefits are described in further detail below.

Water Quality Benefits

Water quality benefits attributable to the Project include enhanced in-stream water quality and surface water quality protection.  These benefits are described in the following paragraphs.

Enhanced In-Stream Water Quality

The new channel design is expected to result in reduced sedimentation throughout the reach, which will generate a reduction in suspended solids within the reach.  The magnitude of this benefit is currently unclear; as such, this benefit has not been monetized.

Surface Water Quality Protection

Implementation of this Project will reduce flood-related debris and pollutant loading in San Francisquito Creek and the San Francisco Bay.  Currently, flood waters leaving the creek channel pass through urbanized areas, where they are likely to become degraded and contaminated with debris, as well as water quality parameters including bacteria, nutrients, floating material, mercury, oil and grease, pesticides, salinity, sediment, settleable material, suspended material.  The O’Connor Pump Station forebay is located within the inundation area.  During flood events, water in this forebay receives increased loading of a variety of contaminants.  The O’Connor Pump Station pumps water from the forebay back to San Francisquito Creek.  As such, the debris and contaminants introduced into the flood waters as they flow through an urbanized area are then returned to San Francisquito Creek, where they may degrade creek water quality and pose a threat to aquatic species and sensitive habitats.  The Project will completely eliminate flooding through the 100-year fluvial event coincident with the 100-year high tide, taking into account a potential 26-inch rise in sea level over the next 50 years.  As such, the Project will provide a significant water quality benefit by preventing transport of debris and contaminants from urbanized areas to the San Francisquito Creek during flooding events.

Further, the Project will provide water quality protection for the San Francisco Bay.  According to Volume II of the Final Report on San Francisquito Creek Hydraulic Modeling and Floodplain Mapping (Floodplain Modeling and Mapping), which was prepared for the U.S. Army Corps of Engineers in January of 2010, during the 250- and 500-year flood events, significant volumes of flood waters leave the floodplain and are discharged to San Francisco Bay (385 acre-feet and 974 acre-feet, respectively).  As described previously, these flood waters flow through urbanized areas, where they are likely to become degraded and contaminated with debris as well as water quality contaminants such as bacteria, nutrients, floating material, mercury, oil and grease, pesticides, salinity, sediment, settleable material, suspended material. 

Although the Project is not designed to the 250- or 500-year storm, it is conservatively designed for the 100-year event.  Even if overtopping does occur during these events, the quantity of water leaving the channel is expected to be significantly less than under the without Project condition, and it is possible that the floodwaters may be contained within the floodplain.  As a result, the Project is expected to reduce pollutant loading – including mercury, copper, and other constituents of particular concern - to the San Francisco Bay during major flood events. 

Other Benefits

In addition to improving water quality in San Francisquito Creek by reducing sedimentation, the Project will provide important ecologic and recreational benefits, as described below.

Habitat Creation and Restoration

The Project will create increased tidal marshland habitat (within new channel) at appropriate elevations for intertidal wetland plant and animal species. The Project is expected to create approximately 16.1 acres of new or improved Mid-Marsh habitat, and an estimated 4.0 acres of new or improved Low-Marsh habitat. 

The conversion of low quality floodplain terrace habitat (dominated by non-native, perennial pepperweed) to higher quality marshplain habitat dominated by native tidal salt and brackish marsh species is the key element to the restoration goals of the Project. This will be accomplished by increasing the tidal prism, thereby increasing the summertime salinities and via the excavation of new marshplains to elevations that will facilitate colonization by tidal salt marsh plant species and deter colonization by ruderal species (e.g. perennial pepperweed).

Another benefit will be the restoration of high tide refugial habitat for sensitive wildlife species at the ecotone between tidal wetland and upland habitats. This will be accomplished via a combination of grading (e.g. levee lowering and grading of stable inboard levee slopes), topsoil preparation, and active revegetation. 

It is difficult to assign a value for habitat creation and restoration.  The San Francisco Bay area is home to 500 species of wildlife, 128 of them threatened or endangered, like the California clapper rail and salt marsh harvest mouse. The Bay is a crucial resting spot for millions of migrating birds, and its sheltered waters provide critical nurseries for fish. (www.savesfbay.org/greening-bay).  Estuary wetlands sustain over 60 plant and animal species that are listed as rare, threatened or endangered or are candidates for such listing.  Of the animal species, the California clapper rail, California least tern, and salt marsh harvest mouse are best known due to their presence on several bayshore properties proposed for development; this Project would provide suitable habitat for the salt marsh harvest mouse and the California clapper rail. 

A well-regarded technique for assigning value to habitat for wetlands is Willingness to Pay.  A 2009 report prepared by EPA entitled The Economic Value of Coastal Ecosystems in California (Raheem et al, 2009) summarizes ecosystem service values found by surveying available willingness-to-pay information and studies worldwide.  This summary presents ecosystem service values for individual ecosystem functions (where available), as well as for bundled services (assumed aggregate value) for estuarine and beach environments.  The range of values for estuarine environments was found to range from $50,000 - $80,000 per acre per year, and beaches range from $36,000 - $83,000 per acre (2008 USD).  Specific values for marsh habitat were not provided.  

Based on these data points, the value of the wetlands created and restored by this Project is conservatively estimated at $50,000 per acre per year (2009 USD).  This translates to an ecosystem services benefit of $1,005,000per year with project implementation, or approximately $14,227,936 over the 50-year project life.

Enhanced Recreational Opportunities

The Project will replace the without-project pedestrian and bicycle trails along the length of the levees to be replaced or modified, but the new levees will accommodate higher traffic due to increased width (16ft) along the crown of the levees.  Additional width of the paved or gravel trails will be created at strategic locations to provide pull out points for pedestrians or bicyclists to let maintenance vehicles travelling along the levee to pass.  Benches and interpretive panels will be placed at the footing of the existing Friendship Bridge on the East Palo Alto side, on the new “island” created at the existing south footing of the Friendship Bridge, and on the new levee on the Palo Alto side.

Information related to current use of existing recreational facilities is limited; as a result, the economic value of enhanced recreational opportunities cannot be quantified.

Enhanced Public Health Protection

In addition to providing water quality, habitat and recreation benefits, this Project will improve public health protection by eliminating exposure to degraded flood waters.  Currently, this disadvantaged community experiences periodic severe flooding.  According to the World Health Organization (WHO), there is an increased risk of infection of waterborne diseases when direct contact occurs with polluted flood waters through wound infections, dermatitis, conjunctivitis, and ear, nose and throat infections.  One epidemic-forming disease that may be contracted from body contact with flood waters is leptospirosis, a bacterial disease.  Leptospirosis may be transmitted through contact of the skin or mucous membranes with contaminated water, damp soil or vegetation or mud contaminated with rodent urine.  Flooding following rainfall assists in spreading the organism due to the proliferation of rodents which shed large amounts of leptospires in their urine.  Leptospirosis outbreaks have occurred throughout the world, with a recent (2007) outbreak on a college campus in Oahu, HI following a flood event.

Even accidental ingestion of flood waters, or of water contaminated with flood waters, can cause a host of infections, ranging from mild to severe.  A well-known example of disease outbreak following drinking water contamination occurred in Walkerton, Ontario in 2000 in which seven people died after consuming drinking water contaminated with E. coli.  In 1999, a dormitory sewage pit on County Fairgrounds in New York caused a major outbreak of waterborne disease, killing two people and hospitalizing 71 others. 

The risk of infection posed by contacting and / or ingesting flood waters is severe.  By protecting this disadvantaged community from floods up to the 100-year event, this Project will remove the real and immediate public health risks posed by exposure to degraded flood water quality.

Reduced Road Maintenance Requirements

As floodwaters recede, a significant volume is left behind in temporary ponds. The Project will reduce ponding on streets and minimize the effect of moisture in creating potholes and cracks, which make up a significant portion of street maintenance costs.

 

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Increases Water Supply Reliability
Advances/ Expands Conjunctive Management of Multiple Water Supply Sources
Increases Water Use and/or Reuse Efficiency
Provides Additional Water Supply
Promotes Water Quality Protection
Reduces Water Demand
Advances/Expands Water Recycling
Promotes Urban Runoff Reuse
Addresses Sea Level Rise
Addresses other Anticipated Climate Change Impact (e.g. through water management system modifications)
Improves Flood Control (e.g. through wetlands restoration, management, protection)
Promotes Habitat Protection
Establishes Migration Corridors
Re-establishes River-Floodplain Hydrologic Continuity
Re-introduces Anadromous Fish Populations to Upper Watersheds
Enhances and Protects Upper Watershed Forests and Meadow Systems
Other (Please Describe)
Increases Water Use Efficiency or Promotes Energy-Efficient Water Demand Reduction
Improves Water System Energy Efficiency
Advances/Expands Water Recycling
Promotes Urban Runoff Reuse
Promotes Use of Renewable Energy Sources
Contributes to Carbon Sequestration (e.g. through vegetation growth)
Other (Please Describe)
(low) - (high)
Drought Preparedness
Use and Reuse Water More Efficiently
Climate Change Response Actions (Adaptation to Climate Change, Reduction of Greenhouse Gas Emissions, Reduce Energy Consumption)
Expand Environmental Stewardship
Practice Integrated Flood Management
Protect Surface and Groundwater Quality
Improve Tribal Water and Natural Resources
Ensure Equitable Distribution of Benefits
Reduce Reliance on the Bay-Delta
Reduce Water Demand
Improved Operational Efficiency and Transfers
Increase Water Supply
Improve Water Quality
Improve Flood Management
Practice Resources Stewardship
Other Strategies (Please Describe)
Groundwater Management Plan
Urban Water Management Plan
Water Meter Requirements
Groundwater Monitoring Requirements
AB 1420 Compliance
BMP Compliance
CEQA Compliance
Water supply reliability, water conservation and water use efficiency
Stormwater capture, storage, clean-up, treatment, and management
Removal of invasive non-native species, the creation and enhancement of wetlands, and the acquisition, protection, and restoration of open space and watershed lands
Non-point source pollution reduction, management and monitoring
Groundwater recharge and management projects
Contaminant and salt removal through reclamation, desalting, and other treatment technologies and conveyance of reclaimed water for distribution to users
Water banking, exchange, reclamation and improvement of water quality
Planning and implementation of multipurpose flood management programs
Watershed protection and management
Drinking water treatment and distribution
Ecosystem and fisheries restoration and protection
Reduced Reliance on the Bay-Delta
Projects that directly address a critical water quality or supply issue in a DAC
Urban water suppliers implementing certain BMPs as on page 17 of Guidelines
Be designed to manage stormwater runoff to reduce flood damage (PRC §5096.827)
Be consistent with the applicable Regional Water Quality Control Plans (Basin Plans) (PRC §5096.827)
Not be a part of the State Plan of Flood Control (SPFC) (PRC §5096.827)

Project team

Part 3 - Benefits