City officials are calling for a ban on natural gas drilling near the city’s upstate reservoirs.

The New York City Department of Environmental Protection sent a letter to the state Department of Environmental Conservation, asking it to establish a one-mile protective perimeter around each of the six major Catskill reservoirs. That would make at least half a million acres off-limits to drilling.

The commissioner of the city’s DEP said she’s not satisfied with the state’s assurances that the reservoirs will be protected from the drilling process, which involves shooting water and chemicals into the ground.

Federal environmental officials say if the city’s water quality goes down, it would be required to build a treatment facility — which could cost $10 billion.

(Source: NY1)