Estuary News

March 2023
Estuary News March 2023

An Inclusive Vision for Bouldin Island

Over resistance from local governments and environmental organizations, in 2016 Southern California’s Metropolitan Water District purchased five islands in the Sacramento-San Joaquin River Delta. While it wasn’t immediately clear what the powerful water agency intended for these islands, the move reminded some Californians of the “Wild West” years of water rights claimed by surreptitious land purchases. Now, years later, it appears the District is making good on that purchase by taking a leading role in Delta restoration efforts.

The Delta Islands Adaptations project, funded through a watershed-restoration grant from the California Department of Fish and Wildlife, has zeroed in on Bouldin Island (the other four islands purchased at the same time were Webb Tract, Bacon Island, Holland Tract, and parts of Chipps Island) as the prime candidate for modeling successful restoration.

To Choose an Island

Situated between Rio Vista and Lodi and traversed by Highway 12, Bouldin Island doesn’t stand out much from the surrounding landscape. On a clear day in mid-February when fields lie fallow, puddles and ponds glisten in the sun while flocks of wintering waterfowl pepper the sky. Egrets and herons wade into the shallows and sandhill cranes hop and waggle in their ostentatious courtship dance.

Groundwater seepage makes large swaths of the island too wet to farm. Courtesy MWD
Groundwater seepage makes large swaths of the island too wet to farm. Courtesy MWD

In the five or so minutes it takes to cross the island by car, only a trained eye would notice the environmental challenges it faces. One such eye, Russ Ryan, senior engineer with Metropolitan Water District and Delta Island Adaptations project manager, takes me on a tour of the island. We start by driving up to the northern levee, climbing about twenty feet up a steep dirt road to the levee top. On the other side flows the South Mokelumne River, swollen from the tide and winter storms. 

Bouldin Island currently lies between 20 and 25 feet below sea level and is estimated to have lost nearly half a billion cubic feet of land volume in the last 40 years. “The primary concern is to stop or reverse subsidence,” explains Brett Milligan, professor of landscape architecture at UC Davis and a leading facilitator during the restoration project’s planning process. “The more the land sinks, the more stress it puts on the infrastructure.” 

Historically, farmers have grown corn and alfalfa on Bouldin’s peaty soils. When the peat is drained, it oxidizes, contributing to greenhouse gas emissions and thinning the layer of arable soil so much so that in some places groundwater seeps to the surface. Large swaths of land on the island are already too wet to farm.

Levee boils can cause massive structural damage if not caught quickly. Photo: MWD
Levee boils can cause massive structural damage if not caught quickly. Photo: MWD

Even considering this extreme subsidence, Bouldin’s selection from the five as the target wasn’t made arbitrarily, but rather through a collaborative process with an iterative feedback loop. “There are two broad ways we did that,” Milligan says. The first was a technical advisory committee with representatives from Delta Stewardship Council, California Waterfowl Association, San Francisco Estuary Institute, and indigenous Tribes, among others. The second was a vigorous public process. 

The committee established ten objectives for island selection including subsidence reversal, restoration opportunities, and water quality and supply. Members then ranked each island in order of their preferred choice and weighted the importance of each selection objective. 

The selection process integrated outside feedback into the committee’s recommendations through surveys and a series of public meetings. “We’ve solicited input throughout the process,” says Milligan. “We’ve found a lot of alignment between the advisory committee and the public, including support both for ecological restoration and continued agriculture.”

In June of last year, the project progressed from selecting an island to developing a mosaic model that best addresses the diverse range of land-use needs, both public and private. The technical advisory committee and public meetings, some with 80-90 attendees, continue to inform progress.

Ryan attributes this feedback-heavy style of decision-making to a leadership change at Metropolitan Water District that prioritizes “innovation, inclusion, collaboration, and partnerships.” He points to new instances of cooperation in historically contentious relationships. “Restore the Delta has shown interest in participating in discussions and providing their input to help inform the work we’re doing,” he says. “We’ve traditionally always been on the other side of the fence.”

He recalls an “a-ha” moment that helped him bring down that fence between the District and Delta advocacy groups. “The thing that joins us is that water quality supports supply reliability, agricultural use, and the Delta environment as a whole,” he says. “If we can make a situation that creates better water quality, it is better for everybody.”

A Landscape Mosaic

As we tour Bouldin Island, Ryan points out a line of short and stout cylinders. “Look how well they’re growing,” he says as he admires the tall thickets of tule reed spilling out over the tops. The cylinders house experimental floating wetlands, a research component informing plans for a new mosaic of land-uses for Bouldin. Data gathered on zooplankton populations (fish food) in the containers indicate that floating peat wetlands could be valuable fish habitat while also capturing carbon in a way reminiscent of tidal wetlands of the pre-reclamation Delta.

Experimental floating wetland cylinders offer promise for fish habitat on the island. Courtesy MWD
Experimental floating wetland cylinders offer promise for fish habitat on the island. Courtesy MWD

Ascertaining how best to balance ecological innovation like floating wetlands with demonstrated cultural and economic benefits of agriculture is at the crux of the current phase of Delta Islands Adaptions. 

In September of last year, the project team presented six visions of a redesigned Bouldin Island to the technical advisory committee. They ranged from near-term scenarios (5-10 years) emphasizing agricultural production to long-term scenarios (25-50 years) focused on habitat restoration, leveraging climate adaptation incentives to make the transition economically viable.

After a five-month process of advisory and public feedback, the project team settled on one near-term proposal with several potential long-term contingency plans. “I think the most significant change is in the collective acknowledgement that we can’t know what the long-term scenario should or could be at this point in time,” says Milligan of the most recent developments. “So we moved towards a range of future scenarios: an adaptive playbook based on a set of if-then propositions.”

While the plan sets aside 50% of the island for continued agricultural uses, farmers currently practicing dry farming will have to come around to some new techniques and ideas to adapt to an increasingly wetter Delta due to both subsidence and sea-level rise. Corn and alfalfa will have to give way to rice and other wet agriculture on a new Bouldin.

Proposed near-term land use scenario for Bouldin Island presented at a technical meeting on February 15th, 2023. These plans will be revised for a public workshop schedule for April 25, 2023. Drawings: UC Davis Metamorphic Landscapes Lab & DIA team
Proposed near-term land use scenario for Bouldin Island presented at a technical meeting on February 15th, 2023. These plans will be revised for a public workshop schedule for April 25, 2023. Drawings: UC Davis Metamorphic Landscapes Lab & DIA team

“You would expect pushback,” says Ryan about proposing sweeping changes to farmers. But he has found otherwise when presenting the benefits of wet agriculture. While rice may not be able to match corn for raw yield, the carbon-capture economic benefit from rice, a crop that doesn’t contribute to subsidence and greenhouse gas emissions, offsets the loss from reduced total production.

A novel type of wetland farming, paludiculture, could also gain a foothold in the Delta through Bouldin Island. Through farming on wet or rewetted peat soils, paludiculture would minimize CO2 production while also producing harvestable biomass. A pilot project on Bouldin could provide a blueprint for larger-scale peatland carbon farming, according to the project website. 

Boiling Over

Ryan stops his car on the levee along the western side of Bouldin Island and shows me a half-circle of sandbags piled three-high with the open end facing the levee slope. A PVC pipe extends from within the circle then down and away from the levee. “We call this a boil,” he says. A boil is when water from outside the island finds its way through a weakness in the levee structure and begins bubbling through on the other side. If the water is murky, it indicates that the surfacing water is bringing levee material with it. If it’s caught quickly, the material can be collected within the sandbag barrier while the water is drained through the pipe. If it’s not, the boil can turn into a major levee breach.

At Bouldin and many other Delta islands, land managers are racing to develop a more sustainable design before sea-level rise and acts of nature turn them into artificial lakes. “Time is critical,” says Ryan. 

To move the project along, the team has relied on both transparency and participation from Delta communities and stewardship groups. “[The Metropolitan Water District] wants a long-term strategy for these islands,” says Milligan. “They will make the final decision, but they’re interested in being a good neighbor and retaining some of those aspects of the Delta that are valued by local communities.”

A public meeting about the future of Bouldin Island. Courtesy Brett Milligan
A public meeting about the future of Bouldin Island. Courtesy Brett Milligan

Public support for the project is broad, and majority opinion aligns well with the technical advisory committee’s stated priorities. Even so, mistrust of the outsider water district remains. Public comments like, “I don’t trust [Metropolitan Water District] at all,” and “how can the Metro. Water Dust. [sic] of L.A buy and own our Islands?” checker the public survey results.

“By bringing these people together you are hopefully initiating a social learning process,” says Milligan. “It’s very different from how we did things in the past: privilege one objective over the others. Generally, I think the benefit is in trying to integrate.”

A final public webinar is scheduled for April 25th, where the designs will be showcased for public input. After that, a Metropolitan Water District decision-maker’s meeting in July will give the final word on the future of Bouldin Island. It’s difficult to say what goes on behind closed doors, but, if the past is any guide, the collaboration and consideration that have defined the project so far should mean there won’t be any surprises.

Then it’s time to hit the ground running on remaking Bouldin Island before the levee boils over.

Top Photo: Aerial view of Bouldin Island. Courtesy MWD

Prior Estuary News Stories

Other Links

Delta Island Adaptations Workshop, April 25

About the author

Michael Hunter Adamson was born and partly raised in the Bay Area and spent his childhood balancing adventure with mischief. As an equally irresponsible adult he has worked for The Nature Conservancy, the arts and education nonprofit NaNoWriMo, taught English in Madrid-based High School equivalent, and volunteers with The Marine Mammal Center. As a writer for Estuary and the editor of the Bay Area Monitor, Michael employs his love for nature and his interest in people to help tell the unfolding story of the living Earth.

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