The Sand Land mine near Southhampton, N.Y., resembles the cratered surface of the moon, a treeless, torn-up work site that underscores the demand for a vital, if often overlooked, natural resource.

Sand is crucial for building — it’s used to make concrete, asphalt and glass. And for over a century, sand from Long Island has helped build New York City’s skyline.

But under the mine, there is another precious commodity: an aquifer system that provides Long Island’s only source of drinking water. The nation is facing a groundwater crisis and Long Island, moreover, has a history of ignoring threats to its water until they become emergencies.

To avoid adding to that history, environmental activists and local government officials want Sand Land to close. The mining operation, they say, is cutting an open wound into the ground that could eventually taint the water underneath.

But sand mining has not damaged the region’s underground water supply, argue those in the business, while state regulators add that there is no reliable evidence of negative effects.

“There has never been an instance of a mine, whether it’s a hard rock mine in upstate New York or a sand and gravel mine on the island, seriously impacting the groundwater in any way,” said John Tintle, the owner of Sand Land.