New York City officials are bridling at an attempt by Long Island legislators to block the city from storing an emergency supply of drinking water under Long Island.

A bill created by Long Island legislators to block the city’s attempt to store water in the Lloyd Aquifer — the island’s oldest, deepest and purest water source — recently passed the State Legislature and was handed this week to Gov. David A. Paterson. Governor Paterson has until the end of next week to sign or veto the measure, which bans adding and storing water in the aquifer.

The city wants to be able to store its drinking water in the Lloyd as a emergency reserve, in case it has to shut down its aging water system for repairs. But this idea does not sit well with many Long Islanders.

“We have geniuses in New York City who say they want to take their chemically treated water and put it in the Lloyd Aquifer,” said Harvey Weisenberg, a Long Island assemblyman who sponsored the law, which would bolster an existing moratorium on new drilling or pumping in the Lloyd.

Mr. Weisenberg said the city water would taint the pristine water of the aquifer with chlorine and fluoride, and as he put it in a letter to the governor, “compromise the health of each and every family in this community.” [our emphasis]

“The thing that bothers me is the arrogance,” he said. “You’ve got to be crazy, out of your mind, to think you would risk tainting the sole source for people on the South Shore of Long Island. It’s one of those New York City-suburb things, the idea that we’ll try what we want because we’re New York City.”

But Mayor Michael R. Bloomberg has urged the governor to veto the bill, and officials with the city’s Department of Environmental Protection, which maintains the city’s water system, say the chemicals in the city water would not contaminate the Lloyd’s water.

“It’s a real city-country thing, this idea that our water’s not as clean as theirs,” said the agency’s commissioner, Emily Lloyd. (“No relation,” she noted about her namesake aquifer.)

Much more important, she said, the ability to add city water to the aquifer would allow the city to make crucial repairs to the Delaware water aqueduct, which provides roughly half of the city’s 1.2 billion gallons of water per day.

“It is not an emergency, but when the time came to make repairs, one scenario is to shut down the Delaware, short-term, to fix the leak,” she said. “And if we did that, it makes sense to store the Delaware water someplace, which they do on the West Coast all the time. One of the aquifers we identified was the Lloyd. If that unlikely scenario happened, we’d hate to see that possibility precluded by legislation.”

The effects of global warming could complicate water supplies in the future, she said, so there’s all the more reason for cooperation, rather than opposition, among neighboring regions.

“I just think it’s too bad they’re looking to unilaterally pass this type of law, instead of sticking together and thinking together about the effects of climate change on ourselves as a region,” she said.

Repairs to the Delaware system, she said, would ensure the long-term sustainability of the system. For years, the aqueduct, a 13.5-foot diameter tunnel, up to 1500 feet deep below ground, has been leaking between 10 and 36 million gallons of water a day. The city system provides water to approximately nine million people in the city, and additional areas north.

Morgan Hook, a spokesman for Governor Paterson, would not comment on the governor’s decision, other than to say: “The bill has been delivered to the governor. He is reviewing it and will take action on it next week.”

The Lloyd, which stretches from mid-Brooklyn to the eastern end of Long Island, is a crucial supply for coastal communities like Long Beach, whose wells have been fouled by saltwater. The state blocked an attempt by Suffolk County to drill into it last year.

Long Island’s roughly three million residents draw water from underground wells, and only about 10 percent of the population get water from the Lloyd. But because of increasing contamination to those wells from pollutants and salt water seepage, the Lloyd has been increasingly looked upon as a fall-back supply.