The whole thing began as homework. In 1960, Professor Everett Turner at the California College of Arts and Crafts assigned his students a collective sculpture project on nearby Bay Farm Island. Photographer Penny Dhaemers documented the effort, and when her images were displayed back at CCAC's Oakland campus, they caught the attention of student John McCracken -- who would later become a celebrated minimalist sculptor, but in 1962 was just a young artist looking for raw material. McCracken found it on the Emeryville mudflats, a crescent of tidal wetland where debris from San Francisco Bay washed ashore alongside trash dumped by local industries. He started building. Others followed. Nobody asked permission, because nobody was sure whose permission to ask. The mudflats sat in jurisdictional limbo -- technically part of Emeryville, practically ignored by everyone except the cordgrass and pickleweed that colonized the muck.

By 1964, the mudflat sculptures had attracted national press. Time magazine called the site a "Mud-Flat Museum." SFSU art professor Alex Nicoloff described the collection as "sculptural graffiti" and compared it to a revival of the Dada movement. The comparison was apt: like Dada, the mudflat art was anti-institutional, anonymous, and deliberately impermanent. Artists built new works from the bones of old ones, cannibalizing a sagging figure's driftwood ribs to construct a fresh form beside it. They called this process "editing" -- a word that captured the collaborative, ongoing nature of the project. No single sculpture was meant to last. The gallery was the process itself, a conversation conducted in lumber and wire and whatever the tide deposited. Some pieces were whimsical: animals, human figures, abstract towers. Others were political, especially during the Vietnam War era and into the 1980s, when works protesting U.S. involvement in Central America appeared on the flats. In 1987, vandals destroyed a Central American solidarity sculpture, a reminder that the mudflats' open-access ethos cut both ways.

What made the mudflat sculptures unique was their audience. These were not works designed for a gallery opening or a museum catalog. They were designed for drivers doing fifty-five miles per hour. The sculptures had to be large enough to read at highway speed and bold enough to catch the eye of someone focused on merging into the toll plaza lanes. This constraint shaped the art in ways no curator could have engineered. Subtlety was pointless; scale and silhouette were everything. A figure had to work as a shadow against the silver bay or it didn't work at all. The best sculptures achieved a strange double life: for the commuter, they were a two-second flash of recognition, a jolt of strangeness in the numbing routine of the drive. For the artist who waded out at low tide to build them, they were hours of labor in cold mud, assembling materials that smelled of salt and rot. The Federal Highway Administration's 1980 report on transportation aesthetics singled out the mudflats as a notable example of spontaneous public art along American roadways.

The sculptures' end came not from censorship or neglect but from ecology. In 1985, the Emeryville Crescent State Marine Reserve was established to protect the salt marsh, which supports cordgrass, pickleweed, eelgrass, and saltgrass -- and shelters the endangered Ridgway's rail. The marsh had been quietly recovering beneath the sculptures, and biologists argued that human foot traffic was damaging fragile habitat. Environmental groups pushed for restoration. In 1997, the California Regional Water Quality Control Board issued cleanup requirements for the Catellus Development Corporation's Emeryville Crescent property, and the last sculptures were removed. By 1998, the mudflats were folded into what would become Eastshore State Park. The art was gone, but the marsh endured -- Temescal Creek still emptied into the crescent, and the rails still called from the pickleweed at dusk.

The mudflat sculptures left no permanent objects, which is precisely why they persist in memory. In 2018, the California College of the Arts (CCAC's successor) mounted an archival exhibition called "In the Mudflats," tracing the sculptures' history through photographs, oral histories, and newspaper clippings. That same year, the City of Emeryville selected two finalists for a permanent public art installation at the Emeryville Marina intended to evoke the memory of the mudflat works. The legacy runs deeper than official memorials, though. Several historians have drawn a line from the mudflat sculptures to Burning Man, whose founders were steeped in Bay Area countercultural art traditions of the kind the mudflats embodied. Tyler James Hoare, one of the few non-anonymous mudflat artists, continued building large-scale outdoor sculptures in the East Bay long after the originals were cleared. The 1971 film Harold and Maude shot a scene among the mudflat sculptures, preserving a few moments of them in amber -- or rather, in celluloid, which may be the closest thing to permanence that art built from driftwood and trash ever deserved.