Reach back 200 years, and the scene before us would be wholly different. The levees, the open water, and the mauve tint of microbial activity in the few still-functioning salt ponds would all be gone. Imagine instead a sea of grasses in all shades of green, from rich emerald to the misty gray of tule and fog, from honeyed lime into the blown-out colors of dried papyrus. Willow trees would be flourishing along freshwater creeks, a ribbon of spotted sandpipers in from South America fluttering over the mudflats. If you can imagine this, then you can at least partially imagine what Bourgeois is trying to bring back.

While the indigenous people of California used the southern spur of the bay to produce salt, it wasn’t until the 1850s, when non-Native, family-run operations began to sprout up, that the tidelands were dramatically transformed. Salt was a hot commodity, vital for both the preservation of food and the mining process that drove hundreds of thousands of prospectors to the Sierra Nevada. So fierce was the demand that local “salt makers” began to alter the bay’s low-lying areas in an attempt to speed up production. They paid laborers to heap dirt along the bayside edges of the mudflats, restricting tidal flow and accelerating evaporation rates. Levee after levee went in, and the rhythmic rise and fall of the bay water through the mudflats and marshes ceased. Over time, Leslie Salt Works took control of each of these relatively small-scale outfits, acquiring one salt farm after another until it owned over 40,000 acres, an area equal in size to around three Manhattans, on the east and west flanks of the South Bay.

In 2003 the state of California purchased many of these salt ponds from Cargill, Leslie’s successor, paving the way for the most innovative and forward-looking wetlands restoration effort in the country. Since then the project area has grown in size, and today it encompasses about 15,000 acres. The project’s staggering size, and its reliable state funding, enables Bourgeois and his team to experiment with landscape-scale interventions that have never before been attempted. At least not in coastal wetlands. And not with the express purpose of trying to bring back what has been lost—while also readying it for a future we don’t really understand.

The night before I visit the South Bay Salt Pond Restoration Project, I stop by the Exploratorium. It is Monday and the museum is closed, but I have arranged for a private viewing of the museum’s Fisher Bay Observatory. Susan Schwartzenberg, the curator, greets me at the entrance and we walk together out the length of the building and into the Observatory itself, which is cantilevered out over the Bay. A car-size topographical map of the region sits in the center of the room. Filtered blue light is projected over the miniaturized landmass, indicating the current shape of the shoreline. “This is where we invite folks to think about sea-level rise,” Schwartzenberg says, turning a knob at the base of the exhibit. But she doesn’t spin it forward, moving the projection into the future; instead, she pulls the projection backward through time. “This is 18,000 years ago,” she says. Back then much of North America was covered in a massive sheet of ice. Sea levels were about 300 feet lower, and the Bay Area’s telltale kidney-shaped bodies of water were almost nonexistent. She slowly turns the knob forward and the projection travels toward the present. There is little variation in the shape of the shore for roughly 5,000 years, then all at once it changes, the ocean rapidly covering up a significant area of dry land.