Bay Area construction company illegally polluted river, lawsuit alleges

A huge quarry owned by one of the Bay Area’s most prominent construction companies has violated water pollution standards more than 900 times in the past six years, according to a lawsuit filed in federal court in San Jose.

Water that builds up in the A.R. Wilson Quarry in Aromas, owned by Graniterock, has repeatedly been discharged into the nearby Pajaro River, which empties into the Monterey Bay National Marine Sanctuary, the lawsuit by Environment California and the California Sportfishing Protection Alliance alleges.

The quarry water contains aluminum, iron, molybdenum, high levels of salts and sediment, and other contaminants that can harm steelhead trout and other fish and wildlife, according to the lawsuit.

One of the largest hard rock quarries in the Western United States, the quarry has been a key source of building materials for the Bay Area and Central Coast for the past 126 years. It is located just south of Highway 129 near Highway 101, where the Santa Clara, Santa Cruz and San Benito county lines meet. Covering 1,000 acres, the open-pit mine is more than 300 feet deep.

The company mines granite and other materials from the quarry to make concrete, asphalt and other products, used widely in roads, schools, housing and highways.

Under state and federal law, Graniterock is required to obtain a permit to release water from the quarry into the Pajaro River. During rainy winter months, when a holding area called Quarry Lake at the site fills up, the company pumps the water into a holding tank and then into the river. The water comes from rain, groundwater and workers washing granite as it is mined and crushed.

Graniterock has released water into the Pajaro River at least 924 times since 2021 that exceeded federal pollution standards, according to the lawsuit.

“These are highly toxic heavy metals that are going right into the river,” said Laura Deehan, state director of Environment California. “It's really damaging and really polluting. The river is suffering.”

The Pajaro River, which drains a watershed that extends across parts of Santa Clara, Monterey, San Benito and Santa Cruz counties, meanders through strawberry and other farm fields before emptying into Monterey Bay near Watsonville. The river has been polluted by pesticide and fertilizer runoff for years, and the mining water adds another burden, Deehan said.

“There's already an ongoing problem with poor river health,” she said. “Steelhead are rarely found in the river, but used to be plentiful. They are threatened by highly toxic pollutants like this.”

Graniterock officials said Thursday that the company will defend itself in court.

“We strongly disagree with the allegations and will respond appropriately through the legal process,” said Shanna Crigger, a spokeswoman for the company.

“Graniterock is committed to good stewardship of our lands,” she said, “and honoring our environmental responsibilities. For decades, we have demonstrated that we care deeply about the health of the communities and ecosystems in which we live and work.”

The company, based in Watsonville, has more than 20 offices and locations, including in San Jose, Concord, Redwood City, South San Francisco, Santa Cruz, and Salinas.

Crigger noted that in 2021 the company, which has been owned by the same family for four generations and has 950 employees, installed a $15 million solar array that provides 65% of the electricity at the quarry. It also worked with the Land Trust of Santa Cruz County to build an undercrossing for wildlife on Highway 17 to reduce collisions between vehicles and mountain lions. And Graniterock has helped with restoration projects she said, along the shores of San Francisco Bay in Alviso and other areas, rebuilding levees as part of wetlands projects.

“They've been a good actor in a lot of ways for the environment,” said Deehan, of Environment California. “But this is not an example of that. We're hopeful we can work with them to clean up the problem and prevent future pollution.”

The lawsuit, filed on Wednesday, stated that the company has been fined four times since 2018 by state water pollution regulators at the Central Coast Regional Water Quality Control Board. In those cases, settlements required Graniterock to pay a total of $138,000 in penalties for water quality violations at the quarry.

For each of the 46 incidents involved, the board imposed the minimum penalty of $3,000, the lawsuit noted, calling it “tantamount to a pay-to-pollute system.”

The lawsuit also says the company hasn’t adequately tested its waters. The company disputed that.

“Our testing protocols are fully compliant with those permits, and we have a long history of being rigorously responsive to the requests and mandates of the Central Coast Regional Water Quality Control Board,” Crigger said. “Nothing about this lawsuit changes our commitment to permit compliance and working constructively with the regional board.”

The environmental and fishing groups said they want a judge to require Graniterock to expand the quarry’s holding pond, treat the water, or take other steps to reduce its pollution into the river. Its permit is currently under review for a 5-year renewal before the regional water board.

Two years ago, in a similar case, Environment California sued the Port of Los Angeles, alleging that it wasn’t properly treating stormwater and groundwater, allowing untreated wastewater with illegal levels of toxic copper and fecal bacteria into Los Angeles Harbor and San Pedro Bay.

Last year, the port agreed in a settlement to upgrade its water treatment systems, and to pay $1.3 million to remove trash and other contaminants from San Pedro Bay. It also paid a $130,000 civil penalty to the federal government.

“Congress allowed for citizen enforcement of the Clean Water Act so that the public could play a vital role in the protection of water quality,” said Chris Shutes, executive director of California Sportfishing Protection Alliance. “When violations become habitual, citizens can demand legal accountability, and that's what we aim to do here.”

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This story was originally published April 16, 2026 at 3:55 PM.