Environmental groups have filed a lawsuit against Suffolk County, claiming the county illegally misused funds to balance its budget at the expense of the local drinking water.

The suit says the county took $33 million in funds from an environmental sales tax that were earmarked for water protection, and instead used the money to plug the county's budget deficit. Critics say the move was illegal.

County officials argue that the fund transfer makes sense. "Right now for the taxpayers of Suffolk County, we have a budget gap," says Deputy County Executive Justin Meyers. "And we can close that gap in the cheapest, most effective way that really has no consequences to it, by borrowing this money and paying it back before it's used."

Today, County Executive Steve Bellone met with environmentalists on the issue. Dick Amper, of the Long Island Pine Barrens Society, says Bellone promised the diverted money will be paid back starting in 2017.

"I think they know that they have to restore the funds and make a commitment to the public that it can't happen again," Amper said.

Environmental groups also filed suit in 2011 when the county's previous administration diverted money from an environmental fund. That suit is still pending, but Bellone administration officials say the $20 million Suffolk diverted from the environmental fund under former County Executive Steve Levy will be paid back along with the current transfer.