Bay Nature magazineFall 2019


Restoring a Watershed in the Heart of San Francisco

September 16, 2019

Water, naturally, seeps or springs up from the ground and flows downhill until it reaches an outlet. To restore a watershed you would need to protect all of that space—the springs, creek, and estuary mouth. To protect an entire watershed in the middle of a San Francisco park visited by 5 million people a year is the kind of thing that takes decades to realize. Between now and summer 2020, that’s a 20-year vision that the Presidio, the city’s military base turned national park, will see fulfilled.

The 270-acre watershed starts three-quarters of a mile inland at El Polin Springs, unearthed and restored in 2011 in the southeast corner of the Presidio. The water bubbles up in a grove of willows and flows down a creek through a large freshwater wetland and meadow called MacArthur Meadow, restored in 2017, where Army troops once camped and assembled. For now, the water flows via culverts under Presidio Parkway, the former Doyle Drive, which was rebuilt in 2015 on a raised causeway to permit the work now taking place beneath it. The water empties into Crissy Field, a thriving marsh built over the old Army airfield from 1998-2001.

In the last step of connecting all the watershed’s parts, the Presidio Trust broke ground in September to restore the creek connecting MacArthur Meadow to Crissy Field. They’ve named the 900-foot new stretch Quartermaster Reach. Over the next nine months contractors will break up concrete, remove contaminated soil, excavate the contours of a new creek bed, remove old pipes and culverts, import several tons of clean dune sand, install custom fiberglass molding for freshwater oysters to latch on to, and oversee the planting of dozens of species of native plants.

“The opportunity, in a city, to go from springs and seeps to the Bay is incredible,” says Michael Boland, the chief of park development and visitor engagement at the Presidio Trust. “This place is a microcosm of the Bay. People plus water plus the whole system.”

On a recent tour of the mostly weedy parking lot where the water will someday flow, Boland was reminded repeatedly of another big concrete-breakup project. “This looks just like Crissy Field did,” he said.

In a way it’s useful to have the reminder so close by, because it’s otherwise difficult to fully understand the scale of the Presidio’s transformation in the last 25 years. Crissy Field, until 1998 an abandoned airstrip, all asphalt and low weeds, turned into this:

Courtesy Golden Gate National Parks Conservancy

Look at the dense coyote brush and the curving shoreline edge, and it can be hard to imagine any other past for the place. We’re practiced in seeing the trees that were cut down and the wildflowers that were paved over to create the parking lot, and much less so in seeing the parking lot that was broken up and the land flooded to create the natural marsh.

Courtesy Golden Gate National Parks Conservancy

So part of the vision is not just that the concrete will disappear to unearth some relic of ecology beneath it. This is not “restoration,” in the technical sense. It’s that the Presidio’s designers and ecologists will create a new place so effectively that ten years from now visitors might walk up the bank of the creek from the Bay-fringing marsh to the springs and never realize that it hadn’t just been that way from the start. They’re going to try to build a working ecosystem, applying the lessons that scientists have picked up from studying different parts of the Bay over the decades.

“We’re creating and unearthing and restoring,” says Presidio Trust ecologist Lew Stringer. “We use the historical ecology to understand what could be here. But we’re creating a new system using the old ingredients.”

About the Author

Eric Simons is a former digital editor at Bay Nature. He is author of The Secret Lives of Sports Fans and Darwin Slept Here, and is coauthor, with Tessa Hill, of At Every Depth: Our Growing Knowledge of the Changing Oceans.