Photo Credits: Micha Salomon (L), Dee Shea Himes (R)

The Healthy Watersheds Resilient Baylands project will enhance resilience to climate change through the implementation of several multi-benefit environmental projects by the San Francisco Estuary Partnership, SFEI, and 15 other organizations. The project has two major components: Multi-benefit Urban Greening and Tidal Wetlands Restoration. Through both components, we are developing science-based strategies that inform the design of innovative implementation projects. By building cutting-edge science into land management approaches, we will demonstrate how green infrastructure and tidal wetlands redesign can improve water quality and ecological resilience in cities, creeks and downstream baylands. Once installed, urban greening projects will reduce stormwater runoff in the cities of Sunnyvale, Mountain View, and East Palo Alto. In addition, construction of a horizontal levee through partnership with the South Bay Salt Pond Restoration Project and realignment of Calabazas and San Tomas Aquino creeks through partnership with the Santa Clara Valley Water District will create transition zone habitat and reconnect watersheds to the baylands, reducing flood risk and delivering necessary sediment to marshes.

 

Multi-benefit Urban Greening

     Photo Credit: Dee Shea Himes

Over the past few decades, interest in greening our cities has grown dramatically following two major developments. Scientific evidence from around the world is showing that despite their reputation as biological deserts, cities support a surprising amount of biodiversity, much of it thriving unnoticed in our midst. This finding has led to the recognition that cities can benefit nature, and that helping nature can be good for people too. In addition, green infrastructure and trees have proven very effective at reducing runoff to stormwater systems, leading to widespread installation along streets and in parking lots. As cities continue to upgrade and green their infrastructure, an opportunity has emerged to achieve better ecological outcomes alongside benefits for people and stormwater. However, to capitalize on this opportunity will require developing coordinated strategies that are regional in scope and that can address how to integrate ecological benefits with other ecosystem services.  

In partnership with the Peninsula Open Space Trust, we are creating a forward-looking, comprehensive strategy for Silicon Valley that integrates water quality benefits with multiple ecological functions to achieve greater ecological resilience. To develop the strategy, we are synthesizing scientific evidence from around the world to develop guidance for how integrated actions can maximize benefits for water quality and biodiversity. Drawing on this guidance, we are identifying opportunities across the region to improve habitat and connectivity and creating recommendations for how to coordinate urban greening activities so that they are synergistic. In addition, we are building links between stormwater management and urban ecological improvements by evaluating how complementary urban greening activities, including green infrastructure and urban tree canopy, can be integrated and improved to reduce runoff and contaminant loads in stormwater systems.

The science-based guidance developed through this project will be used to shape three key implementation projects for stormwater management and urban greening:  

  1. The City of Sunnyvale will demonstrate how bioretention features can create habitat for native pollinators while also reducing runoff. The Caribbean Drive Green Street Demonstration Project will retrofit an existing arterial street with bioretention rain gardens planted with native plants to create habitat for native species, reduce impervious surfaces, provide treatment and infiltration of runoff, calm traffic, and improve the streetscape for pedestrians and cyclists.
  2. Through Google’s Ecology program, Google will integrate ecological design into landscape planning through four innovative projects on their campuses in the bayshore areas of Sunnyvale and Mountain View. Over the past three years, Google’s Ecology Program has sponsored the development of the Resilient Silicon Valley project and the Landscape Resilience Framework by SFEI and partners to catalyze ecological improvements throughout the region. Google will collaborate with the Healthy Watersheds, Resilient Baylands team to maximize the ecological and hydrological benefits of new projects. These projects will highlight how ecologically designed landscaping can create habitat while reducing runoff and improving the human experience.
  3. The City of East Palo Alto, Canopy, and Grassroots Ecology will integrate street tree planting with landscaping and riparian restoration to expand riparian areas along San Francisquito Creek, create willow groves, and connect oak habitat to riparian corridors through adjacent neighborhoods to create more functional wildlife habitat. As part of these installations, the projects will improve soil conditions and understory habitat to maximize water retention, pollution capture, rainfall infiltration, and ecological value of the existing streetscape and parkways. This project will include training of students and other volunteers who will be engaged in native plant stewardship and through tree care events carried out with Teen Urban Foresters from the local community.

Tidal Wetland Restoration

     Photo Credit: Erica Spotswood

Tidal marshes and mudflats in the Bay depend on sediment inputs from surrounding creeks and rivers. Healthy sediment supplies are essential to maintaining resilient marshes that can persist as sea level rises. Suspended sediment in the Bay also controls algal blooms, which can decrease water quality and impact fish and other aquatic species. Currently, sediment trapped behind water supply reservoirs and in flood control channels cannot reach the Bay, creating a deficit that is expected to worsen over the coming decades as sea level rises and inputs from the Central Valley decline. As sediment becomes an increasingly precious resource, the need to develop an integrated strategy for science, management, and monitoring becomes ever more pressing.  

To address this need, we are developing a science-based regional sediment strategy to inform decisionmaking for the resilience of San Francisco Bay wetlands and to improve Bay water quality. The strategy will assess projected bayland sediment demand, sediment supply, and long-term resilience for scenarios that integrate climate change projections with expected restoration and land-use change. Developing boundaries on the minimum and maximum predicted supply and demand for sediment is a key step in this process, enabling managers to anticipate and plan for the most extreme outcomes. We will use predicted sediment supply and demand estimates to develop guidelines and a monitoring strategy that can inform management of sediments for Bay shoreline resilience. The monitoring strategy will be developed in close partnership with the San Francisco Bay Regional Monitoring Program (RMP).

Calabazas-San Tomas Aquino-Pond A8 Implementation

Calabazas Creek and San Tomas Aquino Creek drain parts of Sunnyvale, Santa Clara, and other cities, entering the Bay just east of Alviso. The creeks were realigned in the mid 20th century to make sharp 90° turns at the Pond A8 levee, where they are diverted into Guadalupe Slough. This artificial alignment decreases tidal prism and leads to the deposition of a large amount of sediment upstream, necessitating regular maintenance dredging and some of the highest estimated annual dredging costs in the South Bay. A portion of the sediment dredged from these channels is currently manually excavated and delivered by truck for placement along the shoreline of Pond A8.

SFEI worked with the Santa Clara Valley Water District, the South Bay Salt Pond Restoration Project, and team of science advisors to develop a science-based vision for this complex site. This vision provides a suite of measures that benefit both flood management and bayland habitat restoration under a changing climate. The proposed creek-bayland reconnection that is central to the vision would allow sediment delivery to help facilitate tidal marsh restoration, create a pathway for marsh migration with sea-level rise, reduce the risk of landfill erosion and associated water quality impacts, and improve ecosystem functioning and resilience through the creation of estuarine-terrestrial transition zones. The vision is divided into a first phase with measures that could be implemented over the next decade and a second phase with measures that could be implemented over a longer planning horizon. Upon implementation of the vision, Calabazas and San Tomas Aquino creeks could be the first creeks in San Francisco Bay to be realigned to discharge directly into their historical tidal marshlands— a case study that could be used to inform future reconnection projects in similar landscapes around the Bay and guide responsive policies to climate change challenges.

Dates: 
2016 to 2020
Funders: 
Programs and Focus Areas: 
Resilient Landscapes Program
Landscape Ecology
Integrative Geomorphology
Location Information