Estuary News

March 2017

Corte Madera’s Flood Fight Goes On and On

If you peek through the chain link fence behind the Ross Post Office in Marin County, you will see a suburban creek that looks much like any other. Some sections of bank are armored with riprap and wire, others with concrete, and others not at all. Scattered alders grow at the edge of water that riffles over stone and around muddy bends.

If you peek through the chain link fence behind the Ross Post Office in Marin County, you will see a suburban creek that looks much like any other. Some sections of bank are armored with riprap and wire, others with concrete, and others not at all. Scattered alders grow at the edge of water that riffles over stone and around muddy bends.

The fate of this stretch of Corte Madera creek has been the subject of fierce debate since the 1960s, when the U.S. Army Corps of Engineers slated it for a flood-control design converting the stream bed to a deep, rectangular concrete channel. Before construction stalled, several downstream miles were modified, channelized, or reshaped to remove meanders or fill marshes. Nearly a mile of the creek was straightened and replaced with a concrete box channel that begins just a few hundred feet south of the Ross Post Office, at the entrance to Frederick S. Allen Park.

Half a century and reams of fix-it proposals later, the creek is still flooding. Mud-brown and swollen, the Corte Madera creek threatened to overtop its banks at least twice this winter. Forecasts of heavy rain sent owners of nearby homes and businesses scurrying for sandbags and rainboots, keeping their ears open for flood sirens.

“The incredible winter we’ve had has really put some sunshine on the need for Ross Valley and Marin County to deal with known flood issues,” says County Supervisor Katie Rice. “The rain stepped up public awareness about the need for flood mitigation and revealed that the Corps project, both the finished and unfinished parts, can’t handle a storm of any significant size.”

What’s also different this winter is that for the first time in decades, both public agencies and local advocates are in agreement that more can be done than just keeping the water at bay.

“We see significant opportunities here to not only improve flood performance but also make the creek an amenity for the community and the local ecosystem,” says Christina Toms, Senior Environmental Scientist with the San Francisco Bay Regional Water Quality Control Board.

Toms is one of those responsible for issuing state permits for any flood control fixes for the creek and as a Marin resident she’s watched the creek for years. The concrete portions of the creek are “legendary” in Bay Area flood control circles for their shortcomings, she says.

When designed, engineers assumed the concrete portion could contain the kind of flood that would occur once in 250 years but recent studies suggest it might be barely up to the challenges of a 5- to 10-year flood. In the last century, the creek has had eight floods that caused major damage, six of which occurred since the Corps improvements. The 2005 – 2006 New Years flood was one of the largest on record.

“This project has a unique place in national history, both from a technical perspective and a political perspective,” says Ann Riley of the nonprofit California Urban Streams Partnership, who was formerly with the regional water board and has written two books on urban stream and river restoration. “First, it began the discussion among engineers about the inherent flaws in the designs of these kinds of channels. And second, it inspired the first political protests in California against these kinds of projects.”

The original 1960s plan to extend the concrete channel through Fairfax—over five more miles—was scrapped decades ago. At one point, Marin residents faced down bulldozers to stop the project from moving forward.

One Marin resident at the time, Barbara Boxer, got particularly upset about project. “People say it was responsible for her entry into politics,” says Riley, adding that later Boxer became chair of the Senate Environment and Public Works Committee. The committee oversees the Corps, and Boxer was very focused on Corps reform.

Photo Credit: Jacoba Charles

Work on the undeveloped stretch of the project that is called “Unit 4”was put on hold in 1972, and since then planning has stopped, started, and been revised many times—but no consensus has yet been reached, and no ground has been broken.

Now the project is moving forward again, but still at a snails pace. The environmental review process began in 2008, and is now at the evaluation and design stage. Digging parts of the channel deeper, building up walls or berms to keep the water contained, elevating vulnerable homes, or some combination of these are options being considered. The plans don’t call for more concrete channel to be built, and some might be removed.

Over the years, the Army Corps has modernized many projects so they also promote ecosystem services such as habitat and fish passage. But the Corte Madera Creek project has been going on for so long that it is still operating under an old, narrowly-focused federal authorization issued in the 1960s.

“The challenge we are having is that it’s hard for the Corps to propose project design measures that [my agency and other resource agencies] would be able to permit,” Toms says. “We’ve been working really proactively with the Corps [to overcome the] considerable environmental shortcomings of the proposed alternatives.”

Different stakeholders prefer different aspects of the alternatives being discussed. Some homeowners have said they prefer the occasional flood to a wall or other change intruding on their backyard. Others feel the opposite. Environmental groups, along with agencies such as the water board, would like to maximize habitat and improve fish passage and see as much as possible of the existing concrete channel removed, says Sandy Guldman, of the nonprofit group Friends of Corte Madera Creek Watershed.

“It’s outlived its life. It’s got rusty rebar. It doesn’t work. It is a disaster aesthetically, environmentally, and however you look at it,” says Guldman.

Historically, Corte Madera Creek and its tributaries were home to steelhead, coho, and chinook salmon. Steelhead can still sometimes make it up the concrete channel, but most are stymied where the concrete ends at a poorly functioning fish ladder.

“Even though there is some pretty decent habitat upstream, the fish simply find it really hard to get there,” Toms said. “Right now that channel is a mile-long gantlet for fish. Literally it’s like American Gladiators.”

Removing the entire existing concrete channel isn’t feasible, Guldman acknowledges. However, she hopes that intermediary stretches of the channel might be returned to a more natural state, modeled on urban creek corridor restorations such as the Prince Memorial Greenway in Santa Rosa. Guldman says it would be realistic to widen areas of the creek that are flanked by public property. Terraced public parks, with walking paths and landscaping, could double as a place for floodwaters to go.

“It wouldn’t be like a real floodplain, but it would provide some structure, some little eddies,” Guldman says. “It would really improve fish passage.”

About the author

Jacoba Charles is a naturalist and science writer. Her first article, at age eight, was about the behavior of ducks as observed from the roof of her family’s barn. It went unpublished. She later graduated from the Columbia School of Journalism (2007). In addition to writing for Estuary News, her work has appeared in The New York Times, Salon, and Modern Farmer, Bay Nature, Marin Magazine, and various literary publications. Her botany blog can be found at and her website is She lives in Petaluma with her family.

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