More Mud Please for Novato Baylands

Sediment



Techniques used to add sediment to the Montezuma Wetlands included hosing it from a sediment laden barge. Photo: Darren Graffuis
21
Mar

More Mud Please for Novato Baylands

Imagine a complex of tidal wetlands skirting San Pablo Bay unbroken from China Camp to Mare Island, providing vital wildlife habitat and protecting inland communities from storm surge and sea-level rise. With stretches of this shoreline formerly diked and drained (or in Hamilton Wetlands’ case, converted to a military airfield), reconnecting it may have once seemed unlikely. Yet today just two gaps remain, one of which is included in a restoration project that’s already underway: Bel Marin Keys. And it’s a doozy. The problem is one of scope—and more specifically of mud. The project site, currently partitioned into fields for agricultural use by a grid of berms and drainage ditches, is so large (1,900 acres), and the land so subsided...
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17
Jun

Three Ways to Feed the Marsh

Seal Beach is drowning. As a result of sea-level rise, subsidence, and limited sediment supply, much of the 920-acre National Wildlife Refuge in Orange County can no longer keep its head above water. Pacific cordgrass, normally exposed at low tides, is being completely inundated. Rare nesting habitat for the endangered light-footed clapper rail is disappearing at high tides. It’s a marsh manager’s worst nightmare, and a potential harbinger of things to come later this century for tidal wetlands up and down the state, including those in San Francisco Bay. The problem at Seal Beach has been building for decades, and by 2016 managers knew they had to act—fast. But options for saving the existing marsh were limited. So on an...
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28
Apr

Science-in-Short ~ Marsh Sediment Podcast

Drift, Drop or Floc? Tailing Sediment as it Moves Through Marsh Margins This June two USGS scientists will be trying to get as close as they can to the edge of the South Bay’s Whale’s Tail Marsh to lay out their tools: tiles, filter paper, current profilers, and other sediment accretion measuring instruments. Estuary Reporter Ariel Rubissow Okamoto interviews reseachers Jessie Lacy and Karen Thorne about what they’re looking for at the marsh edge, and how it may help us answer burning questions about the future of the region’s wetlands. Is there enough sediment in the system to help them keep pace with sea level rise by buildng up their elevations naturally, or do humans need to sprinkle some sediment...
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23
Mar

Sediment Paparazzi

As the Estuary faces drowning marshes due to rising seas, people want to see action – acres saved, walls built, marsh mice whisked to safety after crawling to the tip of the tallest gumplant. In terms of action, “sediment monitoring” doesn’t come immediately to mind. Monitoring is something you do after all the action is over, isn’t it? And as for “sediment,” well what’s all the fuss over some dirt and mud? In fact, there is quite a fuss. The Bay region has a sediment management strategy and a sediment monitoring and modeling strategy, and later this month it will have a new sediment supply and demand analysis. Indeed, six different workgroups of Bay scientists, managers, and regulators are now...
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15
Jun

Alameda Creek: Harnessing a Watershed for Public Sediment

In Resilient by Design team Public Sediment’s effort to unlock Alameda Creek, the key lies in sediment--raw material needed to build levees and raise marshes so shorelines can withstand sea level rise. “We’re designing a suite of special structures, a mix of living and constructed features, to move more sediment and create a dynamic new equilibrium for the creek,” says team leader Gena Wirth. To get a conversation about sediment going, Wirth’s teammate Claire Napawan will often start by talking about trout. “Lots of the seniors around here remember fishing in the creek,” says Napawan. “We’re looking for ways to make the watershed culturally relevant to the residents.” When RbD first began working various bayshore sites, Alameda County flood control...
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15
Jun

Supply Side Synthesis

“Small sensors are the foundation of big science,” says Phil Trowbridge, director of the Bay’s Regional Monitoring Program which has just released a new synthesis report on sediment science. The report, combining the results of eight bodies of work, yielded some surprises concerning how much sediment moves from the Sierra and Bay watersheds to the Golden Gate. “The system is calming down after two huge disruptions,” says David Schoellhammer of the U.S. Geological Survey, referring to hydraulic gold mining and dam building. While the supply remains somewhat stable, how much stays in the Bay and how much ends up in the ocean remains an enduring question. In any case, the sediment supply spotlight is slowly shifting from the Central Valley...
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14
Dec

After the Burn Comes the Rain

When fire strikes upper watersheds like it did last October, responses can vary widely depending on land use and ownership. “We view wildfire as a natural process,” says Cyndy Shafer of California State Parks. Wildlands and backcountry areas have largely been left alone, but it’s a different story when lands are managed not for ecosystems but for drinking-water quality. “You want to minimize the erosion that occurs on site,” says Scott Hill of the East Bay Municipal Utility District, “we don’t want sediment in our storage reservoirs.” What’s best must be considered on a case-by-case basis.
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Bridges - public shore
01
Dec

Public Sediment Favors Mud

“We’re finally seeing a change in paradigm,” says Brett Milligan regarding how sediment is treated in the Bay Area. What was once considered waste is now considered a resource, and a group called “Public Sediment,” part of the Bay Area Resilient by Design Challenge, are proposing mud rooms, mud berms, mud pathways, and top-to-bottom mud management to better build up Bay Area shorelines and keep them above rising water.
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16
Dec

No Drought of Dirt

With its massive environmental and economic costs, it’s hard to see a bright side to the California drought. Consider mud, though. According to US Geological Survey scientist David Schoellhamer, the long dry spell may be giving tidal wetland restoration efforts an unexpected boost by promoting the buildup of sediment in the South Bay where former salt ponds await conversion to tidal marsh.
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19
Jun

Hamilton Done, But More To Do

Breaching the outboard levee near Marin County’s Hamilton community this May is cause for both a whoop of celebration and a sigh of relief. Celebration because it was an ambitious wetland restoration project with a complicated design and multiple partners that wasn’t easy to pull off, yet in just a few months it’s become a beautiful landscape filled with blue water, green shoots, yellow flowers, quacking ducks, and happy neighbors. Relief because at times the costs and challenges of moving so much mud to the site, in order to the raise the elevation of subsided wetlands, seemed overwhelming to those in charge. But they did it. And now they need to do it again; only this time they hope it...
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