Climate-Smart Conservation in the San Francisco Bay

Integrating climate science into marsh restoration and conservation efforts

Its pre-dawn and the gate to the Oro Loma marsh in San Leandro, California is locked. On the metal latch hangs a necklace of about ten U-locks, which grant scientists and land managers access to the marsh. I have the key to one of the locks and am here this morning to collect data on birds in the ecologically restored tidal marshes that lie beyond the gate as an intern biologist with Point Blue Conservation Science.

Photo of Don Edwards MarshPhoto by JKehoe_Photos A marsh in the Don Edwards San Francisco Bay National Wildlife Refuge.

The sun has risen, and I stand motionless at my first survey point, watching and listening for birds. North of here, San Francisco looks like a ghost-city in the fog, only the tops of the tallest buildings visible and wavering in the light. My surveys are focused on species of birds that tend to indicate healthy marsh habitat in the Bay Area, including song sparrows, marsh wrens, and the endangered Ridgway’s Rail. Land that was described to me by one biologist as being mostly mud flats in the mid-1990s is now teeming with marsh vegetation and birds. The data I am collecting today will help assess what changes have occurred here since restoration work began, part of Point Blue’s long-term study of marsh birds in San Francisco Bay.

Thought to have once covered nearly 200,000 acres, San Francisco’s tidal marshes saw a drastic decrease in area during the late nineteenth century and much of the twentieth century due to dredging, infilling, and diking. Beginning with the amendment of the Clean Water Act in 1972, development of wetlands in the San Francisco Bay mostly ceased. Since then, a host of organizations have been working to restore ecological function through tidal marsh restoration at the landscape scale. The 365 acres of marshes at Oro Loma were restored in 1997 by breaching the levee that had held back tidal water of the San Francisco Bay. It is one wetlands restoration project among many in the San Francisco Bay Area, which is currently under the transformative gaze of conservation organizations interested in restoring ecological function of the San Francisco estuary at the landscape scale.

Unfortunately, despite restoration efforts, sea level rise caused by climate change is an emerging threat to these marshes, including the one I’m surveying. In the San Francisco Bay, rising sea levels may drown the vegetation that serves as the foundation for tidal marsh habitat and has the potential to essentially undo much of the ecological restoration that is currently underway. With sea level rise of up to 1.65 meters anticipated over the next century, significant work is being done to understand how the tens of thousands of acres of restored Bay Area wetlands will respond to rising water.   

In an endeavor that is increasingly known as climate-smart conservation, scientists, conservation organizations, and managers are working together to prepare for these types of climate-related challenges. Climate-smart conservation is a set of conservation practices that connect climate change scientists with those doing conservation work, and integrates climate research into on-the-ground management solutions. “Climate-smart” may sound like a buzzword, but the term is allowing a diverse range of actors to quickly speak the same language as they produce research and develop management strategies for dealing with climate change.

At the Oro Loma marsh, climate-smart conservation is already being implemented. As I survey for birds, the Oro Loma Sanitary District is constructing a novel structure that may help protect marshes and urban infrastructure from the impacts of climate change. Known as a horizontal levee, the structure is designed to treat wastewater from the wastewater treatment plant directly adjacent to the Oro Loma marsh. In this design, treated wastewater passes through the subterranean layers of the levee and is filtered by the microbes and material within the levee and by the roots of plants growing on the levee’s surface. The levee itself can protect the treatment plant from inundation — which will be more and more important as sea levels rise — much like a normal levee would. It will also provide a more gradual slope for upland habitat than a typical levee would, which will allow wetland species to migrate upwards as sea levels rise. Additionally, the levee’s filtration system allows treated freshwater to enter the estuary at its surface where it can be used by wildlife, instead of being pumped irretrievably into deeper waters. 

While still an experiment, the horizontal levee at Oro Loma is an innovative approach to climate-smart conservation because it incorporates ecological restoration while also addressing climate-related changes that will impact infrastructure. In an interview posted online, California state Senator Bob Wieckowski said of the horizontal levee, “I see the horizontal levee project fitting into the state’s overall effort to respond to sea level rising, because…it’s a terrific example of the state’s need for adaptation projects,” and called the project an “environmentally friendly way” of responding to sea level rise.

Efforts like these to link conservation and flood management may prove to be an important opportunity for Bay Area conservation organizations involved in marsh restoration. Storm surges corresponding with high tides in the San Francisco Bay have caused destructive flooding in the past and will increasingly threaten urban areas as sea levels rise. In fact, a 2013 report by the Bay Institute recommends incorporating the restoration of marshes into the region’s flood management plan.

The question remains as to how marsh restoration and long-term management can be improved in a way that establishes marshes that are more resilient to sea level rise. A few ideas are on the table. Mangers are increasingly looking at dredged material as a possible sediment source for building and maintaining marsh elevation, and are more frequently incorporating upland areas into marsh restoration design. Currently undeveloped uplands adjacent to marshes, though scarce, could be prioritized for land conservation to allow marshes to migrate upwards in response to rising sea levels. 

Conservation organizations are also creating tools, reports, and recommendations for managers to help facilitate climate-smart conservation. The California Landscape Conservation Cooperative (CLCC) hosts a climate commons, a digital library of tools for integrating climate science into conservation work and climate-related initiatives across the state. The CLCC has funded 25 projects in California that actively integrate climate science into landscape conservation. One such project, Point Blue’s Future Marshes online tool, allows users to easily model changes to all of San Francisco’s marshes given user-set variables for the amount of sea-level rise and sediment input.

Tools like these could prove useful in the Bay Area, where scientists think that many marshes have a good chance of keeping pace with sea level rise for the next 50 years through the process of accretion. Scientists also acknowledge the large degree of uncertainty surrounding the two variables that best allow marshes to cope: the amount of sediment-rich water entering the San Francisco estuary over the next century, and the degree to which sea levels will actually rise.  Increases in salinity across the estuary will also affect marshes in the bay.

Climate change poses a unique challenge to place-based conservation because of the drastic changes it brings to the landscape. As temperatures warm and sea levels rise, climate-change will challenge managers in new and interesting ways and demand updated, long-term management strategies for wilderness areas, parks, and ecological restoration projects. Across the globe, it is clear that conservation organizations and managers alike must look towards future climatic conditions, as opposed to merely historical conditions, in order to meet their goals. 

I finish my final survey in the marsh and walk back towards the entrance. The tide has changed, the activity of birds has shifted, and human activity beyond the borders of the marsh is increasingly loud as people begin their day. As the city wakes up in full force, the marsh seems to me even more important, as a way to maintain balance in a complex urban landscape and support the ongoing health of the people, plants and wildlife that live here. 

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