First, get the facts on LI-NYC water

Mankind has been fighting over water for thousands of years. Surprisingly, the latest skirmish over this prized and precious resource is between Long Island and New York City.

The city must make critical repairs on major leaks in the upstate aqueducts that deliver its water, so it needs additional sources while parts of the system are shut down. Its solution: reopen 23 shuttered wells in southeastern Queens to pump some 33 million gallons daily.

The problem is those pumps will draw from the aquifers that are Nassau County's only source of water. Four of them tap into the Lloyd aquifer -- Long Island's oldest, deepest and cleanest source of water.

There's reason to be concerned. We do not have the data needed to evaluate whether this pumping can be done safely.

How will the city's draw affect the water table? Will it exacerbate saltwater intrusion into the aquifers? Will it change the flow of underground plumes of contamination? These questions must be answered before permission to reopen the wells is granted.

It's also fair to ask whether Nassau is doing its best to conserve what it views as "its" water.

The county has its own over-pumping issue. The last state Department of Environmental Conservation groundwater management plan for Long Island, completed in 1986, estimated Nassau could safely pump 180 million gallons per day. DEC figures show the county pumps 275 million gallons during peak season, largely due to watering of lawns. After nearly 30 years, the "safe" number might need to be changed, but clearly there is room for self-examination. The looming battle with the city suggests it's time for Nassau to confront its own usage.

The city's permit for the wells -- some have been closed for nearly 20 years due to pollution -- expires in 2017 but the upstate repairs are slated to begin in 2020. So the permits must be renewed by the DEC. But developments have left Nassau suspicious of the city's intentions.

The city Department of Environmental Planning says it will do an environmental study on the impact of reopening the wells, but it has twice postponed the study's start, now slated for the fall, and has not been clear about its scope. Nassau officials also worry that after spending $200 million to reopen the wells, the city won't turn them off one year later when repairs are done. Since those wells were shut down, homeowners in southeastern Queens have experienced severe flooding from a rising water table.

Nassau's angst is understandable. It's easy to see why our local state legislators are writing bills to require the state DEC to shepherd the city's environmental review. Putting both on notice is reasonable. But assuming bad faith on the part of the city, no matter how tempting, is going too far.

Only the data can lead to the correct outcome. DEC promises a comprehensive review and says permit renewal will be based at least in part on the review. That's good. But it must bar the city from reopening the wells sunk into the Lloyd aquifer. That water should be used only in an emergency, and this isn't one.

A battle is brewing. But let's get the science before we go to war.