Flooding from Corte Madera Creek along Kent Avenue in Kentfield (2005)

I live in the flatlands of Kentfield. Yards from my house, the Corte Madera Creek flows through a mile-long concrete channel box connecting Ross Post Office with the salt marsh just beyond the College of Marin.

When my family moved to Kentfield in 1996, I was a little surprised that we were required to purchase flood insurance as a condition of receiving a mortgage, but I didn’t think too much about it. Having grown up in San Francisco, I was used to living in the shadow of imminent peril from an earthquake, so this was no big deal. 

Since I hadn’t done my homework, I had no idea that the Corte Madera Creek had already overflowed its banks many times, with the floods of 1925, 1955, 1982 and 1986 causing significant damage to Ross Valley homes and businesses.

Also unbeknownst to me, the Corte Madera creek had been “contained” in the concrete chute by the Army Corps of Engineers in the 1960s. And yet the careful observer would note that there had been serious floods in 1982 and 1986, after the construction of the chute.

Corte Madera Creek channel in January 2023	Flooding in Ross, 1925 (Source: Marin History Museum)	The Corte Madera Creek widens out when liberated from the channel

All was well until December of 2005, when a month of steady rain followed by a New Year’s Eve deluge caused the creek to spill out of its concrete channel and rush down the street alongside my house. The flood caused more than $100 million in damage countywide, affecting 1,600 homes and 240 businesses. Luckily for me, my house was not seriously damaged because it was built on a low rise (another thing I had failed to notice when we moved in).

At the time I remember assuming that the county would take swift measures to prevent this from happening again. And yet, here I am 18 years later, still perched precariously along the side of a concrete chute and still paying flood insurance! It isn’t exactly the “banks of the mighty Mississippi” so can’t we contain this piddly little stream?

Increasingly, water management experts would say that we can’t and we should stop trying to do so.

So let’s dive (last water pun, I promise) into the current thinking about creek restoration, looking specifically at the Corte Madera and Lagunitas reparation efforts in Marin.

What is Nature-Based Creek Restoration?

In her wonderful book called “Water Always Wins,” Erica Gies argues that we have to find ways of “conserving or repairing natural systems, or mimicking nature to restore some natural functions — not building more concrete infrastructure. These eco-systems can buffer us from bigger rainstorms and longer droughts by absorbing and holding water. When we obliterate them, we make our places brittle, multiplying the intensity of these disasters.”

Advocates of a nature-based approach have been around for a long time. In the 1970s, for instance, following protests from Marin residents, plans were abandoned to extend the Corte Madera Creek’s concrete straightjacket all the way from Ross to Fairfax.

And while this “Slow Water” approach seems sensible, it is of course easier said than done and Marin’s progress toward the goal of nature-based reparation has been slow and uneven.

Plans for Restoration of Corte Madera Creek

One important thing to keep in mind is that the Corte Madera Creek is one of many creeks in the 28 square-mile Corte Madera (or Ross Valley) Watershed, which includes the towns of Larkspur, Corte Madera, Kentfield, Ross, San Anselmo, and Fairfax. There are many small- to medium-sized creeks in the area, totaling a length of 44 miles. The point is that everything is interconnected, and it’s hard to tweak one part of the ecology and ignore all the other parts.

Water water everywhere (most of the time) (Source: MCSTOPP)

This interconnectedness makes “fixing” the channel by my house problematic and explains why finding a good solution to the environmental, fiscal, technical, and property issues has taken a very long time. It has been 15 years since the beginning of the review process and the actual construction work has not yet begun.

	Parts of the channel that are not next to private property can be removed to allow for expansion (Source: Friends of Corte Madera Creek Watershed)

The current plan is to widen the channel where it passes through public land. The high concrete walls will be lowered or removed to create terraced parks with walking paths and native landscaping. These improvements will slow down the water, provide an overflow area for floodwater, allow groundwater absorption, and support a wider variety of plant and animal life.

The portion of the concrete chute closest to the salt marsh will be replaced with a natural earthen channel to improve fish and wildlife habitat. Farther downstream, the plan is to remove the current rip-rap slope protection and restore the naturally vegetated stream banks.

If this all sounds simple and straightforward, think again. If you click here to read the 238-page report describing the project, you will see why the cost of this project is estimated at $14 million. Work is expected to begin in 2024.

Broken fish ladder in Ross

Don’t Forget the Fishies!

To me it has always seemed amazing that a fish can be born in a stream in Fairfax, swim to the Pacific Ocean as a Twix-sized juvenile, spend 18 months in the ocean growing into a two-foot-long adult, and swim all the way back to Fairfax to spawn. 

The Corte Madera Creek used to be home and transportation corridor for adult steelhead, coho, and chinook salmon travelling to and from the ocean. The coho and chinook salmon have given up entirely, and although steelhead can sometimes make it up the concrete channel, they can’t get past the decrepit fish ladder by the Ross Post Office. The proposed restoration plan includes removing this ladder as well as creating larger fish resting pools in the channel.

Juvenile coho salmon (Source: Press Democrat)	Coho salmon swimming upstream to spawn (Source: Center for Biological Diversity)

In the past, the premiere spot for coho in Marin was the Lagunitas Creek. Fully 5,000 nesting females used to lay eggs in the Lagunitas Creek watershed each year, but the number has dropped to only 500 fish in recent times. However, thanks to the combined effort of the Salmon Protection and Watershed Network (SPAWN) as well as local, state, and federal agencies, significant restoration of the Lagunitas Creek appears to be giving the coho a second chance.

Restoration work has been ongoing for over five years, including the removal of over a dozen residences, outbuildings, and wells remaining from two long-abandoned towns bordering the creek. These structures were replaced with native trees and plants, allowing the creek to meander slowly along curving banks and form pools created by small islands and carefully placed logs. This new habitat is paradise for juvenile coho, who like cool, shady pools where they can rest for several months after hatching and fatten up (kinda) before embarking on the 33-mile trip to the sea. Click here to read more about the project. 

Work on the restoration of Lagunitas Creek will continue indefinitely now that the county — under pressure from a lawsuit by SPAWN and the Center for Biological Diversity — has adopted a Stream Conservation Area Ordinance mandating improvement of the riparian habitat and water quality for coho and steelhead in the San Geronimo Valley and Lagunitas Watershed.

	Before and after images of Lagunitas Creek restoration (Source: Turtle Island Restoration Network)

Water Always Wins!

Sometimes it can seem impossible to solve the complex problems we have created by unrealistically attempting to divert, dam, bury, and contain waterways. And indeed, after first learning about all these problems I decided to avoid writing about urban creek restoration and instead did a Notebook post on how to repair watersheds in nonresidential areas by throwing a few beavers into the local stream and calling it a day. So much easier to write about and so much cheaper to do!

But challenging though it may be, careful restoration of waterways in urban areas will ultimately cost less than the expenses incurred by the flooding, drought, fire, and biodiversity loss attendant to old-fashioned methods.

Interested in Learning and Doing More?

I highly recommend Water Always Wins: Thriving in an Age of Drought and Deluge by Erica Gies. Gies has traveled the world to learn about the innovative ways that “water detectives” prompt us to abandon the fruitless quest to control water with levees, drains, and aqueducts and allow it to move slowly through wetlands that hold water, carbon, and life.

Another great book is Sacrament: Homage to a River by Geoff Fricker and Rebecca Lawton. Fricker’s amazing photographs of the Sacramento River takes the reader from prehistoric ammonite fossils to weekend revelers floating downstream in outsized inner tubes. Lawton’s thoughtful commentary extols the beauty of the river and outlines the steps we can take to ensure its survival.

Friends of the Corte Madera Watershed was founded in 1994 to advocate for the watershed by encouraging residents and businesses to adopt creek-friendly practices and by working with local governments and public agencies to develop policies that benefit natural ecosystems. You can participate in their creek clean-ups and habitat enhancement projects on public property.

SPAWN (Salmon Protection and Watershed Network) is another local group devoted to enhancing the wellbeing of local waterways. Focused on Lagunitas Creek, SPAWN offers opportunities to learn about the endangered salmon, restore watershed habitat, raise native redwood trees, and study salmon health.

If you live near a waterway, a lovely book called the Creek Care Guide, published by the Marin Countywide Stormwater Pollution Prevention Program (MCSTOPP), will help you learn how to maintain the health of nearby creeks by making sustainable choices in terms of landscaping and home maintenance.

That’s it for this installment of the Environmental Forum of Marin Notebook!
Learn more about EFM and the Notebook at marinefm.org.