Estuary News

March 2021

York Creek Uncorked

York Creek free flowing at last. Video: Daniel McGlynn.

Over the summer, while most of the Bay Area was figuring out how to navigate the COVID-induced shelter-in-place orders, 1,933 heavy truckloads laden with 22,000 yards of material wound their way away from Napa County’s York Creek, and were dumped into two nearby landfills. Extracting these spoils was the last step in the York Creek Dam removal project, the culmination of decades of effort by the city of St. Helena to take down a small earthen dam with a big ecological impact. The dam blocked fish from spawning in the creek’s 4.4-square-mile-watershed.

Though the project seemed straightforward, no one involved in its conception could have imagined the convoluted path to its completion forty years later, nor just how difficult and expensive it would turn out to be for a small city to tackle a heavily regulated dam removal project and watershed.

The former dam site is to the southwest of Spring Mountain Road, which tightly wends its way up a grape growing valley snuggled in the Mayacamas Mountains. The descent of the creek is steep and fast — at its head its banks are lined by a cool redwood-dominant mixed evergreen forest, which, by the time it arrives at the elevation of the dam site, becomes more of a transitional chaparral forest that smells like summer where the sun hits the manzanita. What’s as notable as the soft gurgle of the creek washing its way through the dam site on the way downstream, is that most of the watershed is still heavily singed as a result of the Glass Fire last fall, which consumed 67,484 acres in Napa County. All along Spring Mountain Road, piles of burnt logs and other debris are stacked along the guardrails. At the dam removal site itself, bright green willow shoots are popping out of black, scorched earth.

Today, York Creek flows freely from its headwaters in the hills above the Napa River, which the creek feeds. The dam site is about two-and-a-half-miles upstream from that confluence and was first constructed in 1900 to create a reservoir for residents of St. Helena and the surrounding vineyards. Amber Manfree, a Napa Valley native and geographer, remembers as a kid in the 1980s that the reservoir still kind of looked like a reservoir.

By the time the dam was removed in 2020, a forest of alder, willow, and invasive ivy had grown in the sediment infill behind the barrier, rendering it useless for water storage. There are hundreds of obsolete, small dams just like York Creek’s scattered across California’s watersheds. These aging dams show the same issues — they no longer provide water supply, they trap increasingly scarce sediment upstream, and they obstruct fish passage to spawning grounds.

Restoration work along York Creek channel post dam removal. Photo: Daniel McGlynn.

Talk of removing the dam on York Creek first started in 1992, after routine maintenance on the dam’s reservoir outlet went wrong and enough fine silts washed downstream to the Napa River to choke the water and cause a noticeable fish kill. The California Department of Fish and Wildlife (formerly Fish and Game) filed a legal complaint. The city studied the prospects of removing the dam but was unable to obtain the necessary federal and state permits.

In 1997, the California Central Coast steelhead was listed as a federally threatened species. That left York Dam blocking access to 1.5 miles of prime steelhead spawning habitat, which only ratcheted up calls for action. In 2001, St. Helena officials started working with a handful of regulators and permitting bodies that would eventually need to stamp the project so it could move forward.

If the funding, design, and actual construction of any infrastructure project are challenging, the number of permits required to move the York Creek project forward were more so. In the end, permits had to be procured from eight agencies, each requiring expensive planning and documentation, including the California Department of Fish and Wildlife, U.S. Fish and Wildlife Service, National Marine Fisheries Service, U.S. Army Corps of Engineers, San Francisco Bay Regional Water Quality Control Board, State Historic Preservation Office, Napa County Public Works, and Bay Area Air Quality Management District.

The project languished in a permitting quagmire until 2010, when the National Oceanic and Atmospheric Administration started fining St. Helena $70 a day because of lack of compliance with earlier agreements to remove the dam.

By 2020, the total amount paid by the city in daily fees exceeded $190,000, wrote consultant Amber Manfree in a California Water Blog post. Permitting issues continued for another decade until a grant funding expiration deadline loomed.

Like the permitting struggles, the price tag of the dam removal project grew over the years.
The York Creek dam removal project was funded by a 2015 $987,876 grant from the U.S. Environmental Protection Agency’s San Francisco Bay Area Water Quality Improvement Fund, which was matched by the same allocation from the city’s general fund, and an $800,000 Proposition 84 Round 2 Integrated Regional Water Management (IRWM) Implementation Grant. (IRWM’s role in water infrastructure improvement and cross-jurisdictional action often occurs out of the limelight, but since 2002 the program has allocated a total of $1.5 billion to many of California’s more pressing projects.)

“If you look at the funds spent in 2020 by the city for consultants and contractors for this project it adds up to $4.5 million, which was 68 percent of the [city of St. Helena’s] water department’s total budget,” says Jenn Hyman, director of engineering at EKI, the Oakland-based engineering firm that took over in the last year of the project and got the final project design approved and completed. “For the city to take this on was immense financially, so the grant funding was really important.”

An expiration date on the IRWM grant spurred York Dam forward. “We knew we needed to finish the project, the funds were not going to be available indefinitely,” says Natasha Dunn, IRWM grant manager and environmental planner at San Francisco Estuary Partnership.

The project’s lengthy funding and permitting phase brought with it a train of different design consultants over the decades — each offering their own design suggestions to the city. These ranged from minor improvements all the way to a complete reimagining of the creek’s channel through the project area. Eventually, the city settled on removing half of the historic sediment deposits and then creating a “notch” to guide the creek through the remaining sediment. The idea is that over time, the creek will gradually transport the sediment to the decades-starved lower reaches of the creek.

“Originally, we were going to take everything out,” says Erica Ahmann Smithies, St. Helena’s director of public works, city engineer, and York Creek project lead for the past four years. “Then we changed the design to let nature take over.” This process will help improve both overall riparian habitat and steelhead-specific habitat. Rather than leave to chance where all of that sediment will end up (the uncertainty was an issue for permitters), 36 logs were strategically slung across downstream locations to catch sediment and create pools. The logs are bolted to trees still growing along the creek’s banks — and how best to anchor them (they are connected with long steel bolts) was also a topic of permitting talks.

Log sediment structure anchored to tree and burned in fire. Photo: Daniel McGlynn

The vision of trying to keep things simple and use local materials installed in natural forms, like log catchments, was in part informed by the permitting process and in part by a recent high-profile dam removal project on the Carmel River. After years of study and an $83 million dollar investment, San Clemente Dam (18 miles inland from the coast in Monterey County) was removed in 2015.

A massive fire subsequently swept through the area, followed by winter rains that created 30-year flood type events, wiping out restoration efforts. “They did everything by the book according to the regulators and then had mother nature come in and wipe everything out,” says St. Helena’s Ahmann Smithies. “So the permitters wanted to take a less aggressive approach with the construction and engineering on this project.”

Singed forest at York Creek. Photo: Daniel McGlynn

Officially, the York Creek deconstruction began in late June and ended three days before the Glass Fire in September, all of which was within the grant-funded window. The Glass Fire burned 67,484 acres in Napa County and most of the watershed, and damaged six of the new log structures. Contractors worked 12-hour days through COVID-induced restrictions in order to hit deadlines. In some regards, working through the pandemic was beneficial because there was less traffic congestion in Napa Valley, which meant trucks removing sediment could move back and forth from the dam site to the dump site relatively easily (traffic concerns were one of the major issues addressed in the project plan). Contractors revisited the site post-fire to fix the log structures, wrapping up by early November.

Today the creek meanders through the newly created channel on its way to Napa River. A team of engineers and biologists contracted by St. Helena will now monitor the restoration efforts, including how the remaining sediment travels through the watershed. And they will be on the lookout for the return of the steelhead.

“It just took too long,” says Ahmann Smithies while recounting the history of the project. “Everyone wanted to get to the finish line, but it was like the environmental two-step trying to get everyone to agree that their needs were being met.”

Dam outfall before removal. Photo: California Water Audit

Related Prior Estuary Stories

Calaveras Dam Tweaks Yield Results, March 2020

Rebooting the Klamath, Removing 4 Dams, March 2020

Top Video: Daniel McGlynn

About the author

Daniel McGlynn worked as an itinerant naturalist, trip leader, and wilderness guide before serving as an environmental educator with the Peace Corps in rural Nicaragua. Realizing that storytelling is a great educational tool, and productive way to inspire understanding and change, he then turned his attention to science and environmental writing. He is an alum of UC Berkeley’s Graduate School of Journalism and his work has appeared in a handful of national publications. He frequently writes about infrastructure projects and restoration work for Estuary News. Connect with him at

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