Oyster farm turns to salt — local and artisanal
Hog Island’s harvest from Tomales Bay uses 18th century technique
In a small, steamy workshop overlooking Tomales Bay, Jeff Warrin stands over a large, shallow tub built atop a wood-fired brick oven. He’s bringing a bath of seawater — amber-hued at precisely 29% salinity — to a gentle simmer.
Slowly, the surface begins to crust over like a frozen winter lake. “It’s a beautiful, magical process,” says Warrin, an artist and experimental filmmaker-turned-salt maker, describing the final step of crystallizing sea salt.
He could also be referring to the fruits of a yearlong experiment to harvest it off the Marin County coast and create Hog Island Saltworks. The new venture from Hog Island Oyster Co. uses an obscure, 18th century method of evaporating seawater to produce a modern and hyperlocal take on the most basic of foods. And the low-impact salt harvesting process will soon become integral, founders note, to creating a circular and more sustainable aquaculture operation for the
“It’s a beautiful, magical process.”
Salt maker Jeff Warrin
well-known Bay Area oyster farm.
The company’s inaugural harvest — a light, crusty finishing salt — will be used and sold at its oyster bar in Tomales Bay and Hog Island restaurants in Marin, San Francisco and Napa, and available for online purchase, just in time to add a dash of local zest to holiday tables.
Flaky, delicate and deep in flavor, the finished product is a far cry from your ordinary pantry staple. From its provenance and harvest to the hands that craft it, everything about this mineral-rich sea salt seems rooted in its Marin surroundings, including, ultimately, the artisanal price point: From $10 to $15 for a 4-ounce jar. On Hog Island Saltworks’ website the company describes its flavor as having a unique “merroir” — a sense of place specific to these waters.
“It’s like our oysters,” says Warrin, who heads up Hog Island Saltworks. “So much of the flavor of this salt has to do with Tomales Bay,” he adds. Its pristine waters are naturally filtered by 160 acres of bivalves that remove nitrogen and other runoff from nearby farms.
Currently, just a handful of sea salt harvesters pepper American coastlines. Here in the Bay Area, where Ohlone people first evaporated salt in tide pools, and later, Gold Rushera entrepreneurs built dikes to harvest salt, frequent fliers may be familiar with a birds-eye view of one of the country’s largest industrial salt operations, owned by agricultural giant Cargill. This massive kaleidoscope of red and green algaehued salt ponds in San Francisco Bay — much of which is being slowly restored into wetlands — relies on the sun to evaporate seawater over the course of several years. Most small-batch producers, including Oregon’s Jacobsen Salt Co. and Humboldt-based Pacific Flake, speed up the process on land by firing up giant kettles.
Inspired by picturesque, sundried harvesting ponds in France, Hog Island co-founder John Finger had long entertained the idea of sea salt production as a way to expand his company’s sustainable farming practices. (Hog Island, established in 1983, is a registered California Benefit Corporation and has participated in carbon capture and ocean acidification research.) “The wheels started turning” several years ago, Finger said, after the company acquired a neighboring ranch located just up the hill. While most of the 250-acre parcel will remain pastureland, about a fifth of it will support oyster cultivation and packing, where the harvested bivalves will spend their last few days in holding tanks onshore.
At Hog Island’s existing operation, which is perched on the water’s edge near its oyster and clam beds, seawater used in processing the bivalves is simply returned to the bay. An inland location, however, complicates discharge, as environmental regulations prohibit the disposal of salt water into the ground.
“I began to wonder if we could make salt out of that instead,” Finger said. “And then I heard there was this crazy guy playing around with salt in Bolinas.”
Warrin, whose art has been shown at SFMOMA and the Whitney Museum in New York City, began his new project as a pandemic hobby. “People were making bread, cheese and fermented things,” he said. “But no one was making salt.”
Living along the foggy Marin coast, Warrin was all too familiar with unreliable sunshine, and quickly dismissed the idea of making salt by solar evaporation. Nor did he want to boil water all day, he said, concerned about the environmental impacts of continuously burning fuel to heat up kettles. He settled on the graduation tower, a traditional, Northern European contraption. The harvesting method harnesses the wind to extract moisture out of seawater as it dribbles down a multistory stack of blackthorn branches. A 12-foot-high lumber-framed tower, Warrin’s minimalist interpretation looks both sculptural and kinetic. In lieu of branches, a set of nine repurposed clam nets, each an enormous black sail, shimmers with trickling brine and flutters in the bay breeze. A solar-powered pump recycles the cascade, while the wind — along with any available sun — works to gradually concentrate the saline over the course of more than a week. By the time Warrin transfers the saturated solution to the simmering bath, it’s more than eight times saltier than seawater: a suspended brine almost ready to precipitate. As the crust forms over the warmed surface, he gently rakes it off, spreading it across a drying tray like a miniature Zen rock garden. Yet rather than coarse, grainy crystals, the salt’s texture has more of a shaved ice quality — crisp shards that hold a light clump, and shatter on the tongue with a rich, bright tang.
Generally speaking, the salt that fills most shakers is highly processed to deliver a singular flavor — the distinct bite of pure sodium chloride. But seawater contains nearly 50 trace minerals, many of which remain present in sea salt. Warrin estimates that his salt is about 75% sodium; the remainder includes a host of essential elements such as magnesium and potassium.
Tomales Bay’s nutrient-rich water “tweaks up the flavor of the salt,” says Finger. Rippling with a briny and lightly bittersweet savoriness, “there’s a complexity to it, almost like the umami in our oysters.”
Those ties to Hog Island’s main crop are, in fact, about to get tighter. In addition to expanding its oyster processing operations uphill, right next to the graduation tower, the company recently received a longawaited state permit to cultivate seaweed. With the inland production yard soon to be awash in seawater, capturing the salt effectively turns the multipronged enterprise into a fully circular, no-waste system. With 1,500 gallons of seawater yielding roughly 300 pounds of salt, Warren and Finger acknowledge that, at least for the time being, the production will remain a small-batch, niche product. And at $10 to $15 per 4ounce jar, the finishing salt inherently lends itself to judicious sprinkles. “It’s not a megaproject by any stretch of the imagination, but it’s so synergistic with what we do here,” Finger said. “And what we do is really all about place.”