Cutting-edge research at Bay Area wetlands

Sherman Island, anactive research site for wetland scientists. Photo courtesy of Delta Stewardship Council
Sherman Island, anactive research site for wetland scientists. Photo courtesy of Delta Stewardship Council

Wetlands offer us a myriad of benefits, including flood protection, habitat for much-loved wildlife, and beautiful scenery for the public to enjoy.  But did you know they also potentially offer significant carbon sequestration services?

Carbon sequestration occurs when carbon-containing greenhouse gases — specifically carbon dioxide (CO2) and methane (CH4) — are removed from the atmosphere and the carbon they contain is stored in the ground or ocean.  The carbon may be converted into solid, immobile forms that stay in the soil or in biomass for long periods of time.  This carbon is therefore no longer in the atmosphere contributing to the greenhouse effect.  If an ecosystem absorbs more carbon than it emits, it is called a net mitigator of climate change.  (It is important to note that methane is more than 25 times more potent of a greenhouse gas than carbon dioxide over a century).

Wetlands, with their high biological productivity, could play an important role in sequestering carbon, as we progress towards a future with net-zero or even net-negative carbon emissions.  And, if this sequestration can be accurately quantified, it could make wetland restoration projects eligible for financial reimbursement through carbon credits, bringing in additional funds for these efforts.  But what impact do wetlands have on a large scale, and how do factors such as water salinity and the plant species palette influence the ability of wetlands to sequester carbon?

Scientists are busy studying these issues through field experiments and computer models.  Several local researchers presented their findings in December at the 2015 American Geophysical Union (AGU) Fall Meeting in San Francisco.  Here are summaries of three relevant projects:

Water salinity and carbon sequestration

United States Geological Survey (USGS) Biologist Frank Anderson and his colleagues measured the fluxes of methane and carbon dioxide from a brackish marsh in Suisun Marsh, located in the northern part of the San Francisco Estuary. Brackish water is semi-salty, and exists where freshwater from rivers and deltas meets ocean water. The researchers found that saltier waters reduce methane emissions from the wetlands growing there. A class of chemicals present in seawater, called sulfates, is responsible for this inhibition.

However, freshwater wetlands are known to contain a higher density of biomass compared with salty water marshes. More biomass means more carbon dioxide pulled down from the atmosphere to form that biomass.

Therefore, further study is needed to determine if a “sweet spot” exists where the water is salty enough to inhibit methane emissions, but fresh enough to allow for high-biomass species.  One factor to consider is the ability of tidal flows to change a marsh’s salinity, and therefore its emissions, on a short-term timescale. Learning more about these issues could help influence where and how to restore wetlands around the Bay for maximum carbon sequestration benefits.

Estimating the impact of restored wetlands

UC Berkeley graduate student Sara Knox and her collaborators tested the validity of using satellite data and photography to measure vegetative productivity in wetlands.  Part of the motivation for this work is that in order to facilitate carbon credits for wetland restoration projects, reliable yet affordable ways to quantify ecosystem gas fluxes are needed.  Accurate data can currently be obtained from towers installed in wetlands that have wind speed and gas analyzer instruments.  However, they can cost twenty- to seventy-thousand dollars apiece, and may not be able to be deployed on the widespread scale needed.

By contrast, taking pictures on-site and analyzing publicly available satellite data is much lower-cost.  The researchers took photographs of two restored wetlands in the Sacramento-San Joaquin Delta, and obtained land cover satellite data.  They plugged this data into models to estimate biomass creation, also known as gross primary production (GPP). For both methods, their GPP estimates closely correlated with actual figures obtained from towers in the field.  Since plants uptake carbon to create biomass, this suggests that relatively inexpensive techniques may be available to estimate wetland carbon sequestration.

Additionally, they found that of the two wetlands, the more recently restored one was actually a net greenhouse gas emitter, while the more established one was beneficial from a greenhouse gas standpoint in two of three study years. This raises the possibility that greenhouse gas emissions from wetlands decrease over time.

Greenhouse gas variability in restored wetlands

UC Berkeley graduate student Gavin McNicol and his collaborators studied the exchange of greenhouse gases at a restored marsh at Sherman Island, located in the Sacramento-San Joaquin Delta.  They were interested in how and why emissions of methane, carbon dioxide, and a third greenhouse gas called nitrous oxide vary temporally and spatially in the wetland.

The researchers calculated the emissions coming from both vegetated and open-water areas.  Vegetated areas emit gases through pores in plant tissue.  Open-water emissions occur through diffusion, where gases move up gradually through soil and water towards the surface, and ebullition, where accumulating sediment gases form bubbles and eventually burst through the soil to the surface.  For this analysis, they used water samples and computer models, and also collected data on gas concentrations in the air above the marsh and in trapped gas bubbles.

The researchers found that vegetated areas had a smaller net greenhouse effect stemming from their emissions than did open-water areas.  This is because vegetated areas’ higher uptake of carbon dioxide counteracted their higher methane emissions, whereas open-water areas mainly released carbon dioxide.  They also found significant seasonal variation in emissions, suggesting that changing biological productivity, temperature, and other factors make wetlands a dynamic and variable player when it comes to mitigating climate change.

These results could help inform how much vegetated versus open-water area restored wetlands should aim for.  They also provide insight into what factors control the underlying chemical reactions which create and consume greenhouse gases in wetlands.

Save The Bay works to restore wetland habitats around the Bay, increasing our regional ecosystems’ ability to mitigate climate change and its impacts.  We rely on volunteers to make our projects possible.

Taking the Long View at Bair Island

Inner Bair breach
Bay waters flow into Inner Bair Island culminating decades of community activism and wetland restoration.

The modern environmental movement has sometimes focused on responding to sudden, urgent crises.  Think oil spilling into rivers, species plummeting towards extinction, or toxic chemicals sickening people.

Indeed, Save The Bay was founded in 1961 in response to the alarmingly rapid decline of the San Francisco Bay.  Much of this organization’s early work was to stop the imminent destruction of large portions of the Bay for land “reclamation” purposes.  It was natural and even necessary to think in short-term time frames, so as to quickly react to rapid-fire developments and shifting tactics.

Today, with threats of new bay fill largely eliminated, attention is turning towards confronting the long-term threats to the Bay from climate change and sea level rise.  This increases the importance of careful planning and collaboration amongst various stakeholders to achieve successful restoration and protection of the Bay’s wetlands, which form a crucial defense against damage from extreme weather and encroaching waters.

It also requires working with nature itself, which restores degraded landscapes on a (often gradual) timescale of its own.

Persistence pays off at Bair Island

One timely example illustrating this shifting approach is the Bair Island restoration project in Redwood City, which celebrated a milestone on December 10 when a perimeter levee separating the Bay from Inner Bair Island was breached.  This moment is significant because it marks the completion of the nearly decade-long, $7 million project, some 35 years after the land was under threat of residential and business development.

Historically a flourishing wetland, Bair Island by the 1980s had been used for decades for agriculture and salt evaporation ponds.  In 1982, Mobil Oil owned the land, and wanted to construct a new development called South Shores on Bair Island.  A citizen’s group called Friends of Redwood City quickly arose to oppose this project, and through grassroots campaigning helped stop Mobil’s plans at the ballot box that year.

Since then, a long-running, multi-step process has been underway to complete the circle of ecological restoration at Bair Island.  First, the land was purchased by an entity that would ensure this outcome.  In 1997, the Peninsula Open Space Trust (POST), a local land trust, bought the land for $15 million.  In 1999, POST transferred the land to state and federal government agencies for inclusion in the Don Edwards San Francisco Bay National Wildlife Refuge, ensuring its permanent protection.

Then, a restoration plan needed to be crafted and funded.  A key collaborator in this process has been the conservation non-profit Ducks Unlimited, which pieced together much of the funding from government and foundation sources.  Construction began in 2006 and is now finishing up.

Investing for future challenges

Bair Island’s decades-long journey towards rehabilitation shows how complicated restoring ecosystems can be.  Local activists have successfully protected sites like Bair Island from reckless development around the Bay, which now must be restored to wetlands to benefit our region.  Chief among the challenges of accomplishing more projects like this one is finding the needed money.  Funding streams from the government, particularly through federal appropriations, can be unpredictable and inconsistent.  Contributions from foundations and individuals can significantly ebb and flow when the state of the economy changes.

Given this, having a dependable source of money would accelerate the timeline for pending and potential projects.  Like Bair Island, many of these projects could take decades from beginning to end.  So, we need to get to work now to see the benefits by the time sea level rise and climate change becomes more severe later this century, as stated in a recent scientific report.

The San Francisco Bay Restoration Authority (SFBRA) is a regional agency empowered to raise money specifically to fund Bay Area wetland restoration, shoreline improvement, pollution reduction, and flood protection. On January 13, SFBRA will vote on placing a measure on the June 2016 ballot that, if approved, would generate $500 million over two decades through a regional parcel tax.  Passing this measure will allow environmental stakeholders to more quickly and reliably undertake restoration efforts in all nine Bay Area counties.

The main threat to a thriving, productive Bay has changed.  We need long-term plans to address climate change and sea level rise.  Call on the San Francisco Bay Restoration Authority to place the Clean and Healthy Bay measure on the June 2016 ballot.

Planting begins at Oro Loma

Oro Loma
Volunteers planted 3,200 native seedlings at the Oro Loma Horizontal Levee Project. Save The Bay will plant 70,000 seedlings at this site over the coming months.

Last weekend, over fifty volunteers gathered at the Oro Loma Sanitary District treatment plant in San Lorenzo to kick off an ambitious burst of planting activity in a soon-to-be restored wetland.  Participants included a contingent of local college students, parents and their teenage children, and a few veteran helpers.  Equipped with trowels and picks, attendees placed 3,200 plants into a plot of soil next to the sewage treatment plant.

Though the plants were all put in the ground in about an hour, an enormous amount of planning went into how they were selected and configured.  Save The Bay’s habitat restoration team has been working for over a year to cultivate several palettes of wetland plants that will be planted next to each other.  They will become part of a scientific experiment exploring what combination of plants and soils can best filter excess nutrients from the treated wastewater that will be pumped in from the adjacent sewage plant.

A new kind of levee

This is exciting, because if this pilot project is successful, it could be replicated elsewhere as a means of naturally improving water quality, providing needed habitat for sensitive species, and forming a more durable barrier to flooding from storms and sea level rise.  This horizontal levee is an alternative to steep earthen or rock walls that traditionally separate the Bay from vulnerable land — this marsh will gently slope upwards, enabling it to better adapt to rising tides.

After the planting was completed, participants joined the public open house being hosted by the Oro Loma Sanitary District.  Horizontal levee project scientists and treatment plant workers were on hand to give tours, and Save The Bay staff answered questions about their work.  Also present were local elected officials, representatives of the Castro Valley Sanitary District, which co-owns the treatment plant, as well as UC Berkeley researchers who will analyze the filtering capacity of the wetland once it is operational.

Over the next two months, our goal is to put in 70,000 plants at this site.  If this project sounds interesting and you’d like to pitch in, you’re in luck!  Save The Bay will be hosting 3 more volunteer planting workdays at Oro Loma, on November 21, December 5, and December 12.  Click here to volunteer!

Tide Rushes in at Sears Point: A Great Example of what Measure AA Can Do

The Sonoma Land Trust captured this dramatic video of the Sears Point levee breach.
More than a decade of planning, permitting, and restoration work culminated on October 25 with the breaching of a levee that had separated San Francisco Bay from a newly restored marshland at Sears Point, located near San Pablo Bay in Sonoma County.  For the first time in over 120 years, tidal flow is now occurring between the Bay and the 960 acre site, which was historically a wetland but had been diked, drained, and used for farming for decades.

The successful restoration at Sears Point illustrates the many benefits of regional Measure AA, which will fund similar crucial projects around the Bay Area.

The new marshland will filter excess nutrients from runoff and prevent them from reaching the Bay.  It will be a carbon sink, sequestering carbon dioxide from the atmosphere.  It will serve as habitat for species like the endangered Ridgway’s rail and salt marsh harvest mouse.  And it will serve as a natural bulwark against flooding caused by future storms and sea level rise.

Previously, the Sears Point Ranch property was proposed to be developed into a casino owned by the local Federated Indians of Graton Rancheria.  However, the Graton Tribe ultimately dropped its purchasing rights for the site in 2003.  The Sonoma Land Trust, which preserves environmentally significant land in Sonoma County, bought the property in 2005 and began working with several funders and stakeholders to restore the ecosystem to its natural state.

The wetland restoration project broke ground in June 2014.  Agricultural hayfields were replaced with a grid of specially designed dirt mounds.  The mounds will help slow the speed of incoming water, causing the sediment contained in the water to drop out and settle into the marshland, where it can help anchor ongoing plant growth.  Additionally, a new levee was constructed to protect adjacent property and infrastructure.  The levee will double as new habitat for species that inhabit the ecological transition zone between the tidal marsh and the upland.

On October 25, hundreds of spectators came to observe the removal of the levee separating the Bay from the future wetland.  Within moments of an excavator crane scooping away the earthen barrier, water began pouring down into the site, to sustained cheers and applause from the gathered crowd.  Attendees were given small pods containing pickleweed seeds in order to participate in the re-seeding of the marshland.  I had the pleasure of witnessing the breach, along with Save The Bay’s habitat restoration director, Donna Ball, and our communications director, Cyril Manning.

The project also demonstrates the value of governmental and non-governmental entities working together towards a common environmental goal.  The Sonoma Land Trust partnered with the US Fish and Wildlife Service, California Department of Fish and Game, and Ducks Unlimited, among others, in funding and planning this $18 million restoration effort.

The work at Sears Point Ranch is by no means complete.  In the coming years, more investments will be made to improve the newly constructed levee, enhance public access, and fully reestablish tidal action and hydrology at the site. However, it is already contributing to a region-wide movement to reverse the damage caused over the past 150 years by wetland degradation and destruction.

According to scientists, the Bay needs to see accelerated action on more projects like Sears Point in next few decades. You can help ensure that the 36,000 acres of baylands awaiting restoration are given the funding they deserve by voting YES on Measure AA this June 7th.