Keeping an eye on the watershed in San Mateo County

Driving north along Interstate 280 toward San Francisco, you’re only a few miles from the sprawling suburbs of San Mateo County.

The views tell a different story.

Crossing south over the Eugene Doran Bridge, the iconic orange “Flintstone House” is nestled among forested hills to the left. Underneath you, the San Mateo Creek runs from the Crystal Springs Reservoir into the Bay. To your right, a glittering blue reservoir is surrounded by hills blanketed in uninterrupted green. Looking out over the Crystal Springs Reservoir, you suddenly feel very far from anything.

This is the Peninsula Watershed, a 23,000-acre tract of land home to the Pilarcitos, San Andreas and Crystal Springs reservoirs. Owned by the San Francisco Public Utilities Commission, the watershed is home to 190 species of plants and animals, and less than a dozen humans.

Watershed Keeper Supervisor Sarah Lenz is one of those few people who live on the watershed. For the past 10 years, she has worked to protect and manage the watershed’s resources with the SFPUC, responding to issues ranging from trespassers to water quality to wildfires. As fire seasons become less predictable, Lenz and her coworkers are on the front lines in fire prevention and response in the Bay Area.

“We’re kind of Jack and Janes of all trades,” Lenz said. “We get to do a lot of different activities. We have chain saws, we get to fix things, we build fences, we patrol, we do firefighting, we do interpretive work.”

A usual day for the watershed keepers involves collecting data and patrolling the watershed. Each day they collect data on lake levels and precipitation, and watch for water quality issues. During their patrols, the keepers use boats, utility and all-terrain vehicles to keep an eye on water quality, wildlife, roads and signs of the occasional trespasser.

“We like to get eyes on each area throughout each shift,” Lenz said.

Their other jobs include managing recreation like docent-led hikes, mountain biking and even equestrian events.

Fire prevention is integral to a watershed keeper’s duties. As part of the “initial response” to any fires in the area, they participate in training with the California Department of Forestry and Fire Protection, Woodside and San Mateo consolidated fire departments, and volunteer fire brigades from Kings Mountain and La Honda. Lenz says that this kind of preparation is essential in keeping SFPUC’s firefighting “up to snuff.”

The SFPUC is hoping to hire some new watershed keepers to fill holes in its ranks. However, even when there are all 12 keepers working (10 regular watershed keepers and two supervisors), it’s a lot of work to split the supervision of so much land between so few people.

“It’s a lot to ask for 12 people,” Tim Ramirez, manager of the SFPUC Natural Resources and Lands Management Division, said. Keepers often work overtime or take on extra shifts, especially as the usual “peaks and valleys” of fire seasons grow less predictable and new shifts are added.

Lenz had to drive up to a high ridge to get a signal for her Zoom call. Despite being located in the highly populated Bay Area, her workplace is very much removed from the rest of the busy Peninsula.

“That is just, every day, one of the most unique things [about the watershed],” she said. “I don’t know that I’ll ever truly appreciate the uniqueness of that.”

Lenz also has a rare front-row seat to the large variety of wildlife living in the watershed. Trail cameras pick up mountain lions almost daily, and she recently saw a badger on Pilarcitos Dam. Deer and wild turkey are fairly common, and marbled murrelets live in the Douglas fir forest. There are even bald eagles nesting in the trees.

“They’ve been successfully nesting for the last 10 years and fledging two to three chicks every year,” Lenz said.

Fire response in a changing climate

Fire is a constant danger anywhere in California, especially areas like the watershed. It’s classified by Cal Fire as a very high fire hazard severity zone, the highest level in the state, Cal Fire Deputy Chief Jonathan Cox said previously.

“Over the last 100 years, we’ve been too good at suppressing fires,” said Cox at a controlled burn on the San Andreas Dam in early June. “We keep fires small, and there’s an argument to be made that there’s a need to reintroduce good fire back into the environment.”

Cal Fire is doing just that, continuing to implement controlled burns in and around the watershed. Meanwhile, SFPUC is clearing dead and nonnative trees to remove fuel and watershed keepers are continuing to train with its partners.

The watershed has already experienced one fire this year. In June, the Edgewood Fire caused evacuations in Emerald Hills. However, Lenz said that the response from the watershed keepers, Cal Fire and the Woodside Fire Department was a success.

Before the Edgewood Fire, the CZU Lightning Complex, in 2020, caused fires throughout the watershed and beyond. Nine lightning strikes hit the watershed one night in August, and Lenz was one of the first responders to the situation.

“We were very lucky in that our staff is here on the watershed and was able to just get out and get after it,” she said. “I feel pretty confident … that that’s a big reason why we didn’t have larger fires.”

Lenz described the fires as a learning experience, bringing positive changes to fire preparation in the watershed. There have been other lightning events forecasted since then and, while they never happened, SFPUC was more prepared. Now, they are staffed “through the night” in anticipation of fires.

“We learned some lessons, so we used those lessons and staffed up,” Lenz said. “I think we all feel a little bit better prepared, as much as you can be for that kind of scenario.”

The watershed’s long history

As Cox said, fire suppression has only been a major issue for the last century or so. For thousands of years, before the first Spanish arrived, the indigenous Ohlone people had been practicing controlled, regular burns as a land management strategy. However, European control led to significant changes in the watershed, including a ban on indigenous burning.

The burn ban, in addition to other factors like the introduction of nonnative species, livestock grazing, logging and hunting, caused significant changes. Beavers and grizzly bears became extinct in the area, plant life changed, and the land was modified for agriculture during the mission era and the Gold Rush.

Much of the original land is now underwater. Dams were constructed in the mid-1800s, and parts of the watershed were submerged by the new reservoirs. Human land use was mostly outlawed in the watershed by the early 20th century, and SFPUC has owned the area since 1930. Now, the hills, creeks and reservoirs are protected by keepers like Lenz, and largely off limits to the public.

Years before she ended up working with the SFPUC, Lenz studied the watershed as part of her education at San Francisco State University. Now, it has been both her home and her workplace for a decade. She watches the seasons change, drives past white-spotted fawns in the morning, and looks forward to the yearly wildflowers blooming.

“Little did I know I would end up here,” she said. “It was not preplanned, but I’m super happy to be here and be part of protecting the watershed and sharing it.”

Information on the history and wildlife of the watershed, as well as a more detailed analysis on how watershed flora and fauna have changed under European settlement, can be found in the San Francisco Estuary Institute’s Peninsula Watershed Historical Ecology Study, published in 2021 for the SFPUC.