Moving in on the last coastal sand mining operation in the United States, California regulators are ordering a Mexican-based company to obtain permits and pay state royalties for its Monterey County plant or shut down — amid a chorus of complaints that it’s causing significant erosion of beaches along Monterey Bay.

The facility, known as the CEMEX Lapis plant, has been in operation since 1906 and is located between Marina and Moss Landing. With smokestacks, conveyor belts and dredges, it produces an estimated 200,000 to 300,000 cubic yards of sand a year — enough to fill up to 30,000 dump trucks — that sells for about $4.70 a bag for a variety of uses from sand blasting to golf course sand traps to lining utility trenches.

On Tuesday, the State Lands Commission, an agency that regulates offshore oil drilling in state waters and submerged tidal lands, sent a letter to CEMEX officials demanding that the company obtain a lease from the commission and begin paying royalties, or shut down.

“Stealing public resources for private profit without a lease is a violation of the state constitution,” said Lt. Governor Gavin Newsom, chairman of the State Lands Commission. “This mine is a relic of an era that California and the nation rejected a long time ago, and it is past time that CEMEX engage in a dialogue on the future of operations.”

Walker Robinson, a CEMEX spokesman at the company’s U.S. headquarters in Houston, said the company hadn’t had the opportunity to fully review the commission’s action.

“The Lapis facility in Marina has been in consistent operation for more than 111 years,” he said. “That the operation is a vested right and has all required entitlements to operate has been repeatedly confirmed over the last 50 years by numerous government entities.”

Last year, CEMEX spokeswoman Megan Lawrence told this newspaper that the company operates the mine in an “environmentally responsible manner and in accordance with applicable laws and regulations.” The mine is also “a much needed resource for many local projects including municipalities, infrastructure and recreational facilities,” she said.

Scientists and environmental groups, however, say the facility is causing significant erosion of beaches along Monterey Bay, from Marina south to Del Monte Beach in Monterey.

“If you take that much sand directly off the beach every year, the waves keep breaking,” said Gary Griggs, director of the Institute of Marine Sciences at UC-Santa Cruz. “The southern end of the bay is eroding at a much faster rate than it would naturally.”

Griggs, who has studied coastal erosion for more than 40 years, said that areas south of the sand plant, along the site of the former Fort Ord military base and down to the Monterey Tides Hotel in Monterey, are eroding at roughly 3 to 6 feet a year. Stilwell Hall, the former World War II-era officer’s club at Fort Ord, had to be demolished in 2003 when cliff erosion threatened to send it crashing into the ocean.

Without the sand plant, Griggs said, the coast in that area would erode by roughly 1-2 feet a year, if not less.

In decades past, there were six major sand mining plants along the shores of Monterey Bay. They used a technique called “drag lining,” in which they scraped and dragged sand with massive metal scoops from the surf line. The companies were closed by the U.S. Army Corps of Engineers between 1986 and 1990, however, after the agency enforced prohibitions on sand mining below the tide line.

The Lapis mine remained open, however, because it had shifted to a method in which it pumps sand from a lagoon on the back of the beach in an area where it owns several hundred acres. Meanwhile, last year the California Coastal Commission said it will require permits, a case that is still open, but CEMEX contends that its operations predate the 1976 Coastal Act.

“Cemex is one of the Coastal Commission’s highest priority cases and our enforcement staff has spent the last year in negotiation with representatives of the company, working long hours in an effort to resolve the situation,” said Lisa Haage, chief of enforcement for the Coastal Commission. “We are deeply committed to this case and remain concerned about the loss of sand and the effect on beaches, access, habitat and infrastructure in the Monterey Bay, particularly in the light of the threat of sea level rise.”

The State Lands Commission noted in its letter this week to CEMEX that the company’s predecessor, Pacific Cement and Aggregates, had a 5-year state lease with the state and paid royalties. The commission’s executive officer, Jennifer Lucchesi, wrote that sand in the lagoon comes in with the tides, so is subject to the agencies jurisdiction. If CEMEX does not apply for a state lease, conduct environmental studies and pay royalties, it could face civil liability and damages, Lucchesi wrote.