State appeals court judges have ruled that an East End sand mining company can no longer process yard waste and construction debris at its Bridgehampton mine.

The 50-acre Sand Land mine has been the target of criticism by neighbors and environmental groups who say the materials processed there could contaminate groundwater.

The March 30 decision by the Appellate Division of the state Supreme Court upheld a 2012 ruling by Southampton Town’s Zoning Board of Appeals that processing waste and debris was not a permitted use at the mine.

The 4-0 appeals court decision reversed a 2014 state Supreme Court ruling against the town in the case. It represents another setback for Sand Land’s owner, Wainscott Sand & Gravel Corp., which last year was denied permission by state regulators to expand the mine amid pushback from neighbors and environmentalists.

David Eagan, the East Hampton attorney representing the mine’s owners, said in a statement that the company was disappointed in the ruling and would appeal. He added that the company “remains deeply concerned regarding the impact of the court’s decision on the South Fork’s vital landscaping and contracting businesses” that dispose of trees, concrete and other materials at the mine.

Sand Land sits within one of Long Island’s nine state-designated Special Groundwater Protection Areas. A January report by Suffolk County health officials found that compost facilities appear to cause contaminants to leach into groundwater and should be more tightly regulated by the state.

Adrienne Esposito, executive director of the nonprofit Citizens Campaign for the Environment, celebrated the decision this week and said state officials should feel emboldened to crack down on similar activities at other Long Island sand mines.

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Esposito has criticized the state Department of Environmental Conservation for allowing mines to operate as “solid waste management facilities” and said she is seeking a meeting with the DEC commissioner in Albany over the Sand Land decision.

“The DEC needs to act like the regulator, and the town needs to enforce the law,” she said. “It’s been a five-year battle with the town and the DEC standing still and doing nothing, and those days have to be over.”

Sean Mahar, a DEC spokesman, said in a statement that the department “aggressively enforces our current regulations” that allow the processing of trees, concrete and other materials at sand mines “and has taken dozens of actions resulting in millions of dollars in violations.” The DEC has also proposed new regulations to strengthen its authority over mulch facilities, he said.

Southampton Town Supervisor Jay Schneiderman praised the town attorney’s office for winning the appeal, but said it has caused concern among landscapers who have relied on the mine for disposing vegetation.

“There’s clearly a need to process yard waste,” Schneiderman said, adding that he is trying to find ways to expand the capacity of the town’s three disposal sites to accommodate the waste.