By Mary K. Miller
The drive down Fire Truck Road to the Montezuma Wetlands Project, where the Delta and Suisun Bay converge with the Sacramento and the San Joaquin rivers, feels out of place from much of the Bay Area, sparsely dotted as it is with farms, cattle and wind turbines rather than housing tracts. Stopping for a closer look, I see that part of this desolate grassland 20 miles from the city of Fairfield is undergoing a radical transformation. Adjacent to Fire Truck Road is low marsh with intertidal channels and ponds surrounded by tall swaths of tule, cattails and bulrush, while towards the foothills grow clumps of salt grass and pickleweed in high marsh.
What took tens of thousands of years for nature to build–the foundation of an ecosystem that is almost equal parts water and muddy ground–took two decades to recreate using a bit of ingenuity, a good business plan and a lot of sediment. The essential ingredient is mud transplanted from places in the Bay where it mucks things up and impedes ship traffic to places where it can be put to good use.
Twenty years after the first barge-full of sediment dredged from the Oakland harbor arrived, the Montezuma site has deployed eight million cubic yards (CY) of the material to raise the subsided pastures and diked baylands back to tidal levels and create 550-acres of healthy wetlands. In the process, endangered mice and young salmon that once thrived here have returned in measurable numbers. Today, the ambitious project continues to demonstrate how the beneficial reuse of dredged sediment can help the region’s wetlands keep pace with rising sea levels.
“We’re probably going to take a million and a half cubic yards this year alone, which is our biggest year ever,” said Jim Levine, director of the privately owned Montezuma Project.
Montezuma Wetlands’ ambitious design, sustainable funding and industrial-level infrastructure are badly needed if the Bay Area is to meet the challenges of coastal resilience and climate change. Like coastal and bay communities across the country, wetlands restoration in the San Francisco Bay and Delta is on a collision course with sea level rise and flooding from extreme storms. According to the San Francisco Bay Conservation and Development Commission (BCDC) and other agencies, the Bay Area needs to restore 25,000 acres of tidal marsh by 2050 to buffer and protect communities and valuable infrastructure (estimates from a recent inventory put the value of at-risk parcels and roadways at $236 billion). That means fast-tracking new and existing restoration projects like the Montezuma Wetlands, which I visited recently on a warm fall day with its director Jim Levine.
No Mucking About
Owned and operated as a private LLC, the heart of Montezuma Wetlands project looks like an industrial harbor with a hulking electric Liberty offloader snorkeling a slurry of sediment and water from a dredge barge docked alongside. At pressures of 200-300 psi, the mud is pumped from the barge through a complex of pipes and valves to deliver it inland and build up land that had subsided 10 feet below sea level after being diked and drained in the late 1800s. Nearby, earth movers shape berms to form enclosed cells with space between them for water to flow, like veins in a leaf. Each cell is individually filled with the mud pumped a mile or more by Liberty.
Within an hour, 2500 CY of sediment is offloaded (the equivalent of 250 dump trucks) and the dredge barge is ready for a tugboat to push it back to the Port of Oakland where a clam-shell dredging rig can fill it again with mud scooped from the bottom of the harbor. At Montezuma, another barge takes its place at the dock, water is sprayed and pumped into the load to make a slurry and the offloader lowers its snorkel and starts pumping again. The project had a record year of sediment offloading, but had additional capacity for even more material which prompted Levine to explore other options. “We’ve even started bringing in construction dirt from the South Bay by barge. It’s all the same, we just have to add more water [to the drier material] to make it flow.”
Permitted to run 24/7, 365 days a year with skilled union operators, Montezuma is a model of efficiency and infrastructure. It has a stable and sustainable source of funding through fees paid by the U.S. Army Corps of Engineers and other dredging operations and contractors to accept material dredged to keep shipping channels, ports and harbors open to vessel traffic. It was also one of the first projects to receive funds from the Bay Area’s Measure AA, a voter-backed parcel tax passed in 2015 to increase habitat restoration in the Bay. In 2018 it was awarded $1.6 million in funds and recently got an additional $2.1 million for Phase II restoration. Since beginning operations in 2003, the Montezuma Wetlands project has accepted 8 million CY of sediment, completing the first 550-acre phase of the 1100-acre wetlands restoration in October 2020. Montezuma is well into Phase II on a parcel adjacent to the Sacramento River with about 15% filled from an expected 300,000 cubic yards of sediment. That the project puts dredged sediment to “beneficial use” by creating new wetlands makes this a unique public-private partnership.
Starving for Sediment
Mud wasn’t on his mind in 1989 when Levine gazed out the window at the Emeryville office of his environmental engineering company, Levine-Fricke, and wondered why he didn’t see more birds. Instead, he often saw barges loaded with sediment from dredging at the Port of Oakland and realized that it was the missing ingredient to create the shallow-water tidal habitat that wading birds prefer. He met with company geologists and biologists to search a restoration site and they found a neglected 1800-acre parcel that would become the Montezuma Wetlands. Owned by Southern Pacific railroad with tracks that were no longer used, it included a deep-water port with a tidal slough cutting through it. What he really needed, after purchasing the land and getting permits in 1992, was mud to fill the site to raise it to above current sea level. That turned out to be more challenging than just diverting barges from the Oakland Harbor to his site.
At the time, the U.S. Army Corps of Engineers, responsible for maintaining shipping channels and harbors in the Bay, had a federal mandate to dispose of dredge sediment in the least-costly manner possible without harming the environment. That meant dumping it at in-bay disposal sites (40%) or, when those reach capacity, 50 miles out of the Golden Gate Bridge at the Deep Ocean Disposal site (20%) with the rest going to beneficial reuse (40%) including marsh restoration. All total, the USACE dredges about 2 million cubic yards a year from San Francisco Bay.
Some ocean disposal is necessary for dredge sediment that is too contaminated for ecological projects, although the design of the Montezuma Wetlands allows for the safe use of sediment containing low levels of contaminants. (Contaminants in bay bottom sediments derive from industrial and wastewater discharges and urban and agricultural runoff.) The project team received permits to use contaminated sediment as a foundation layer at the bottom of each cell with cleaner sediment on the sides and top. Water quality tests at the site show that the design works: contaminants from the soils are sequestered and not entering the ecosystem.
“We need more suitable dredge sediment going towards beneficial reuse if we want our tidal marshes to stand a fighting chance against a rising sea level,” said Scott Dusterhoff, Managing Director and Senior Scientist at the San Francisco Estuary Institute (SFEI) and an expert on geomorphology and sediment.
In their Sediment for Survival report (2021), SFEI did the math on how much sediment is available through beneficial reuse of dredge and natural flow from rivers and streams. The sediment supply fell far short of demand for maintaining and restoring marsh wetlands under sea level rise scenarios of almost two feet by mid-century and another five feet by 2100.
“We calculated that we’ll need 450 million cubic yards of sediment, two times as much as was dug to build the Panama Canal or about 45 million dump trucks worth,” said Scott. “We only have a third of what we need with beneficial reuse and what nature provides.”
The good news from the study, he said, is that the sediment we need is in the region, “We just need to be smart about getting it onto our tidal marshes.” (See also Three Ways to Feed a Marsh.)
That includes reconnecting streams and rivers to wetlands to increase natural sediment flow. There is also sediment locked behind dams where it fills up reservoirs rather than flowing to the Bay. Another largely untapped supply is sediment from flood control and construction projects, where landfill disposal is more cost-effective than transporting the material to restoration projects. “Two million tons of sediment from construction projects are taken to landfills in the Bay Area every year,” said Scott. “We need to find places to stage the material until projects are ready to take it.”
The amount of dredged sediment going to restoration is also increasing. In 2020, the US Army Corps received new guidance to explore “cost-sharing” agreements encouraging the Corps to support more projects that put sediment to beneficial use rather than ocean disposal (their new mandate is for 50% beneficial use). At Eden Landing, part of the South Bay Salt Pond Restoration Project, the Corps is piloting the potential of strategically placing material just offshore and allowing the tides to move sediment into the marsh rather than pumping or dumping it inland.
Reuse Gets Results
After our tour of the sediment offloading operation, we drove past earthmovers and excavators finishing up the day’s work constructing levees and cells to receive sediment for Phase II restoration of the Montezuma Wetland. We stopped along Fire Truck Road to see the results of all that earth moving, dredging, and pumping. The sun was setting on the restored high and low marsh, a quiet landscape of blue ponds and channels surrounded by soft green and gold bulrush. A snowy egret winged overhead while a pair of ruddy ducks paddled in a nearby pond. While I didn’t see them, a herd of tule elk have apparently taken up residence along the high marsh. A team of biologists hired by Montezuma Wetlands have been tracking the return of species, including the endangered salt marsh harvest mouse.
“After restoration, we detected the mouse in really high numbers relative to the rest of the [unrestored] site,” said Montezuma lead ecologist Cassie Pinnell. The biologists she works with monitor special status species at Montezuma including the salt marsh harvest mouse, the Western Pond Turtle and several species of birds, the California least tern and the western snowy plover in particular. In partnership with UC Davis, they also monitor fish in the channels and ponds. Pinnell says they’ve detected a lot of fish at the site, including young salmon. “It’s both a feeding ground and a protective area with lots of hiding places for little fish,” she says. The restored wetland is also expected to benefit several state and federally listed species including Delta smelts and longfin smelt found in this region of the estuary. Tests of water quality show the site at par with the adjoining Montezuma slough. All of which points to a successful tidal marsh restoration and a beautiful place to visit.
Wetlands like Montezuma provide additional benefits that will continue to build as sea level rise and extreme storms threaten the built landscape surrounding San Francisco Bay. When properly connected to rivers and streams for natural sediment flow, wetlands grow vertically and maintain themselves, unlike seawalls and other hard infrastructure that break down over time. The Bay Area needs to identify and set aside more land for future marshes and rebuild those ecosystems in ways that are cost-effective, efficient and non-polluting. It’s a grand challenge for our times, an effort that Jim Levine reflected on as we gazed on the restored wetland. “It’s a beautiful thing,” he said. “It took 26 years to turn this farmland back into wetland but now it’s forever.”
Reporter Mary K. Miller is an independent writer specializing in ocean, environment and climate solutions. She is emeritus program director for environmental science at the Exploratorium where she worked for 30 years. Mary lives in Sonoma Valley and enjoys scuba diving, bicycling, hiking and observing local wildlife on her trailcam.
The story was produced by Estuary News Group for Maven’s Notebook with funding from the Delta Stewardship Council.
