March 29, 2024
Alev Bilginsoy, Outreach Coordinator
US Army Corps of Engineers
San Francisco District
Transmitted via email: shorelinestudy@usace.army.mil
Re: South San Francisco Bay Shoreline Sunnyvale Project Feasibility Study
Dear Ms. Bilginsoy,
The Sierra Club Loma Prieta Chapter’s Bay Alive Campaign welcomes this opportunity to provide comments to the Public Scoping Meeting presentation on the South San Francisco Bay Shoreline (Sunnyvale) Feasibility Study Permanente Creek to Guadalupe River. We do so on behalf of tens of thousands of local Sierra Club members who share our commitment to protect the health of our communities, our wildlife and our Earth by promoting living shorelines, healthy waters, and just, equitable solutions to sea level rise in the San Francisco Bay Area.
Our Bay Alive Campaign advocates for the multi-layered benefits of natural and nature-based adaptation to sea level rise, for regional coordination, and for equitable strategies to build community resilience. We contribute to plans, guidance, and actions under consideration at local, regional and State levels and we serve as members of both the Bay Conservation and Development Commission’s (BCDC) Advisory Working Group and Implementation Group for the new guidelines being developed for the Regional Shoreline Adaptation Plan. In addition, the Sierra Club has stayed involved, for more than a decade, in Specific Plans for the four reaches in the study area: North Bayshore in Mountain View, Google’s Bayview, Moffett Field, Moffett Park in Sunnyvale; we have closely followed the proposed project connecting the mouths of Calabazas and San Tomas Aquino creeks with the Bay and enhancing the the Harvey (CalTrans) marsh.
We attended the public scoping meeting and appreciate the time spent by Alev Bilginsoy, Anne Baker and Lexi Karon of USACE to present information about this project to the Conservation Council on March 6, 2024. We also appreciate their willingness to communicate with the Sierra Club Loma Prieta Chapter and with other environmental organizations on the first phase of USACE’s study in order to understand current conditions, problems, and opportunities. We welcome the opportunity to contribute our insights at this early project stage and look forward to communicating with the US Army Corps of Engineers (USACE) throughout the feasibility study phases and subsequent project phases.
Overview
Presently, a pivotal opportunity exists to integrate habitat protection and restoration into planning for sea level rise (SLR) adaptation. Recent research underscores the efficacy of nature-based solutions in safeguarding coastlines and providing a myriad of ecosystem services.1 The Adaptation Atlas2 serves as a valuable reference and is a starting point for appropriate nature based solutions within the Bay Area. Further studies would be needed to develop appropriate strategies based on a closer study of the shoreline conditions by a science-based organization such as San Francisco Estuary Institute.3
Natural infrastructure typically offers 'no-regret” or “low-regret' options due to their incremental implementation and monitoring requirements, potentially yielding lower upfront costs and greater flexibility over time. Moreover, they provide invaluable ecosystem services that safeguard important wildlife habitats and create new and restored habitats, while simultaneously reducing our communities’ vulnerability and enhancing resilience.
Project area opportunities
Flexibility: In the future, as sea levels rise, shallow water habitats will slowly drown, or adapt by rising using new sediment accumulation, or migrate upland if migration is facilitated. The potential migration of tidal wetlands in response to sea level rise depends on a variety of factors including topography, sediment availability, land use policies, existing infrastructure, and planned or potential actions occurring prior to levee construction. Therefore it is important that specific alternatives be considered and developed so that the feasibility study (hereafter called the Study) builds in flexibility in the face of an uncertain future. In addition, the Study needs to include management processes for monitoring the progress of sea level rise, groundwater rise, and flooding experiences of storm events in the project period.
Groundwater and stormwater: The Study should consider alternatives to address groundwater rise (which can be caused by the pressure of rising seas forcing salt water below shallow groundwater aquifers). In addition, levees can create barriers to storm water drainage to the Bay. Alternatives to the alignment that have been considered so far should be considered with this in mind.
The project area, outboard of the conceptual levee line in your presentation, encompasses two Operational Landscape Units (OLUs) as delineated in the Adaptation Atlas - #22 Santa Clara Valley and #23 Stevens Creek. It includes large stretches of open space and protected areas separating the Bay from urban development. These open areas, comprising mudflats, marshes, and subsided polders are largely safeguarded. There remain some undeveloped areas, inboard of the levee conceptual line indicated, that should be earmarked for potential marsh migration.
We have the following specific suggestions.
- Reserve Migration Space for Tidal Wetlands and Re-Align Levee
Marsh migration space is a high priority and is needed all around the Bay.4 The study area includes potential areas for upland migration space for marshes. These include Harvey Marsh, Baylands Park, Twin Creeks Sports Complex, Lockheed wetlands, Moffett Field Golf Course, the area north of Google’s Bayview Office Complex east of Stevens Creek and west of Moffett Field’s runway.
The proposed levee alignment should be to the landward edge of the above listed spaces. One advantage of moving the levee to the south edges of these spaces is that the levee will be built on a sound foundation of dirt rather than on bay mud. A levee built on unstable bay mud is susceptible to subsidence over time, requiring levees to be built higher and wider. This results in higher costs and more space required for the levee structure in order to spread the weight over a wider footprint. A levee built on bay mud also has a higher probability of damage due to liquefaction of bay mud during seismic events.
- Preserve Stormwater Wetlands landward of levees for natural infrastructure
The City of Sunnyvale recently adopted a Moffett Park Specific Plan Update, that includes preservation of 87 acres of wetlands in the northwest corner of Moffett Park (Lockheed area) and the addition of 17 acres of terrestrial buffer inboard of the wetlands to protect them from development impacts and to create a flood water retention area and space for ecosystem migration. We ask that maintaining and protecting the viability of this essential local ecosystem be prioritized in the Study so that it can be sustainable, providing natural infrastructure, until such time as the levee alignment is moved to the landward side of these wetlands.
- Other stormwater retention areas and pump stations
The study area slated to be safeguarded by proposed levees is predominantly low-lying and areas are already subject to stormwater pumping for flood water control, channeling water into higher-level creeks that ultimately flow into the Bay. Therefore significant retention areas are needed in all four reaches of the project and retention areas adjacent to the levee may need to be expanded. The study needs to take into consideration sufficient storm water accumulation areas for green infrastructure and pumping station locations as part of the sea level rise resilience plan.
- Enhance new marsh opportunities at creek mouths outside of levees
Enhancing connections between creeks and their floodplains in order to increase freshwater and sediment flow into baylands is essential for the much needed increase of tidal marsh and wetlands.5 Stevens Creek provides a significant opportunity. All the creeks should be similarly studied for restoration of their alluvial fans with sediment brought downstream to the creek mouths. In addition to mitigating storm surge, new marshes provide critical ecosystem services including much needed stormwater nutrient reduction, carbon sequestration as well as nurseries for fish and hundreds of other creatures in the food chain.
More new marsh areas are especially critical as they will also provide much needed habitat, with a focus on the endangered Ridgway's Rail. Because Ridgway's Rail habitat is restricted almost entirely to the marshes of the San Francisco Bay, it is considered a good umbrella species for other elements of marsh-dependent biodiversity.6
- Address potential mobilization of contaminants by ground water rise (GWR)
In addition to emergent flooding, the Study should address the potential for shallow groundwater rise to mobilize soil-borne contaminants associated with former landfills, waste treatment plants, and Moffett Field armed forces activities and active airfield. Both the Department of Toxic Substances Control and the Regional Water Quality Control Board have recently taken action to strengthen their oversight of SLR and GWR impacts.
- Consider Ecotone Levees for Sunnyvale Water Pollution Control Plant
The San Francisco Bay Regional Water Quality Control Board is working towards new guidelines that will be require the wastewater treatment plants all around the bay (37 plants) to remove 40% more nitrogen and other pollutants before discharging treated wastewater to the Bay in order to protect Bay water from the damaging algae blooms experienced in the last two years.7
Using a nature-based solution such as “Ecotone “ Levees is one effective natural approach to treat sewer water, and studies show this can remove as much as 97% of nitrate and other pollutants.8 However, the circuitous layout of channels and berms in proximity to the plant make effective Ecotone levees adjoining the plant difficult. Ecotone levees could be possible if landowner jurisdictions pursue revision and/or removal of circuitous channels, opening up room for ecotone construction. or for a significant stretch of Ecotone Levees accessible to the plant for treating waste water. Ecotone Levees provide multiple ecoservices and habitat benefits, as well as providing flood control and potential recreation trails on the levee.
- Alternative using Nature-based Adaptation measures
Among the alternatives considered, one alternative at least should include a suite of nature-based adaptation strategies, that allows, potentially, for a phased adaptation approach, with adaptation pathways, built-in monitoring and specific trigger points for further actions.9 This will allow for a comparison of the value added using nature to capture and enhance the ecoservices provided by such strategies and a more hybrid solution including “grey” infrastructure and hardened or armored shorelines.
- Align with BCDC’s Regional Shoreline Adaptation Project (RSAP)
Please note that the Bay Conservation and Development Commission (BCDC) is currently developing their Regional Shoreline Adaptation Plan guidelines and plan to complete these guidelines by the end of December 2024. These guidelines will dictate the requirements for adaptation plans for all bayshore communities and require these plans to be submitted to BCDC by the end of 2034. Consequently, it is imperative that adaptation of the South San Francisco Bay Shoreline Sunnyvale Project from Permanente Creek to Guadalupe River, for sea level rise, be consistent with these guidelines and its goals.
Hard engineering has traditionally been employed to protect communities in shoreline low lying communities, but as this alternative becomes less sustainable and more costly, with sea level rise projections, flood control managers around the world are increasingly turning to land use planning strategies, such as setback zones or resilience zones to allow for transformation of the shoreline. Burlingame is the first city in the Bay Area to pass a sea level rise ordinance requiring new development to be resilient to sea level rise and includes a 100’ setback “buffer zone” from the bay shoreline in order to provide space for resilience strategies.10 Currently, San Mateo County is in the process of preparing policy guidelines, for use by all cities in the County, that include setbacks for sea level rise resilience for new construction. Please note that Santa Clara County and other counties may need to take similar actions by 2034 in order to meet BCDC’s RSAP guidelines for sea level plans which include “Put Nature First whenever possible”.
We look forward to continuing an ongoing productive exchange of ideas with the USACE on this project.
Sincerely
Susan DesJardin
Bay Alive Campaign Steering Committee
Sierra Club Loma Prieta Chapter
Chair Gita Dev
Chair, Conservation Committee
Sierra Club Loma Prieta Chapter
Cc James Eggers, Chapter Director, Sierra Club Loma Prieta Chapter
Jenny Binstock, Sierra Club Senior Campaign Representative for the Lands, Water, Wildlife initiative of the Our Wild America campaign. jenny.binstock@sierraclub.org
1 A.D.Guerry et al, Protection and restoration of coastal habitats yield multiple benefits for urban residents as sea levels rise. Nature (2022)
Shepard, C. C., Crain, C. M. & Beck, M. W. The protective role of coastal marshes: a systematic review and meta-analysis. PLoS ONE 6, e27374 (2011).
Gedan, K. B., Kirwan, M. L., Wolanski, E., Barbier, E. B. & Silliman, B. R. The present and future role of coastal wetland vegetation in protecting shorelines: answering recent challenges to the paradigm. Clim. Change 106, 7–29 (2011).
2 San Francisco Bay Shoreline Adaptation atlas a collaborative effort between the San Francisco Estuary Institute and SPUR
3 Protection and restoration of coastal habitats yield multiple benefits for urban residents as sea levels rise Study of San Mateo Shoreline 2022
4 Incorporate the San Francisco Bay Joint Venture’s Baylands Habitat Goals Project - to achieve 125,000 acres of tidal marsh, restore and enhance 16,500 acres of transition zone, and protect 14,000 acres of adjacent uplands for marsh migration
5 Same as footnote 4 above.
6 Shorebirds-driven trophic cascade helps restore coastal wetland multifunctionality
Ecosystem restoration has traditionally focused on re-establishing vegetation and other foundation species at basal trophic levels, with mixed outcomes. (This study shows) that threatened shorebirds could be important to restoring coastal wetland multifunctionality
7 Mountain View Voice, March 16, 2024 “The Fight to Rid the Bay of Red Algae may cost 11b” “Ten years. That’s how much time the Bay Area’s 37 wastewater treatment plants will have to reduce fertilizer and sewage in their water by 40%.........The San Francisco Regional Water Quality Control Board plans to adopt the change as part of its new discharge permit requirement beginning June 12 (2024)......”
8 https://oroloma.org/does-the-horizontal-levee-work/ “The removal of nitrate and trace organic contaminants was particularly sensitive to hydrology; rapid and near complete removal (>97%) of these contaminants was observed in water flowing through the subsurface, whereas surface flows did not exhibit measurable contaminant removal.”
9 Dynamic adaptive policy pathways: A method for crafting robust decisions for a deeply uncertain world Global Environmental Change, April, 2013.
10 Burlingame Ordinance 25.12.050 – Public Access, Flood and Sea Level Rise Performance Guidelines