RIVERHEAD, N.Y. (CBSNewYork) — A Long Island animal shelter wants to expand, but clean water advocates with the Pine Barrens Society say the expansion plans threaten the island’s only source of drinking water.

For nearly 50 years, the Kent no-kill shelter has helped rescue thousands of pets from being put to death. Now, shelter managers want to build the rescued animals a better home.

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But Executive Director Pamela Green said several factors are standing in the way, CBS2’s Meg Baker reported.

“This facility will not be able to meet the needs of homeless animals in the future because it is a bit antiquated and in constant need of repair,” Green said.

The state and town of Riverhead have approved a $2.5 million plan to increase the shelter’s capacity 50 percent. But the property lies on the very edge of the protected Pine Barrens and its underground aquifer that provides Long Island’s only source of drinking water.

“Kent is using our affection for puppies to allow them to build over the purest drinking source on Long Island — it’s prohibited by law,” Executive Director of Long Island Pine Barrens Society Richard Amper said.

The Long Island Pine Barrens Society wants the project killed and thinks the town should donate property for it elsewhere — angering shelter supporters, Baker reported.

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“I think it’s a great use for the Pine Barrens, it’s nature, they’re part of nature, they’re living creatures,” said Joann Brinker-Shirley of Suffolk County.

Shelter managers say the expansion is pro-environment because it includes moving buildings away from the nearby Peconic River while adding a bigger septic tank to prevent groundwater contamination.

“Our plan presents a solution,” Green said. “It’s almost the duty of the Pine Barrens Society to be in favor of this project.”

Green says she’s asking the State Pine Barrens Commission to grant a waiver.

“If the commission acts politically because of puppies and breaks state law that protects water, we’ll go to court,” Amper said.

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The state commission will now try to make heads or tails of this controversey at a public hearing at Brookhaven Town Hall on Wednesday.