ALBUQUERQUE, N.M.—It could be 30 years before a huge plume of contamination at Kirtland Air Force Base reaches the nearest drinking-water wells in New Mexico's largest city, according to a report released Monday by the U.S. Environmental Protection Agency.

Federal regulators made the draft report public in response to a Freedom of Information Act request that was filed by the Albuquerque-based watchdog group Citizen Action.

The report covers a number of scenarios that were modeled in hopes of getting a better understanding of how the underground plume of spilled jet fuel is moving. While it will likely be some time before the contamination reaches the closest city wells, there's uncertainty around the speed at which it will reach a smaller well operated by Albuquerque's Veterans Affairs hospital.

Scott Ellinger, the report's author, said in an interview Monday that it would be best for city, state and base officials to control the plume now rather than wait.

"The further it gets, the more it spreads, the more it's going to cost," he said.

The fuel came from what officials believe was a 40-year leak from underground pipes at a Kirtland aircraft fuel-loading facility. It was discovered in 1999, and officials are still trying to figure out how to clean it up before it hits city water wells.

The spill has been estimated as large as 24 million gallons, or about twice the size of the Exxon Valdez oil spill.

While there have been other fuel spills around the country, EPA officials acknowledged Monday that the Kirtland spill is unique given the depth of the plume, which puts the cleanup of the mess in uncharted territory.

The Albuquerque Bernalillo County Water Utility Authority has been working with officials at Kirtland and the New Mexico Environment Department to characterize the spill and develop options for cleaning it up.

"While the models show plenty of time, we don't want that to become a cause for complacency on anyone's part," utility spokesman David Morris said.

Not addressing the contamination could have big economic and infrastructure impacts for Albuquerque, Ellinger said.

Just last week in West Virginia, thousands of gallons of a chemical used in coal processing leaked from a plant into the Elk River, forcing a ban on tap water for some 300,000 people. Restaurants and schools closed, and people were told to use the water only for flushing their toilets.

In Albuquerque, Citizen Action has long complained that contamination of groundwater resources could be devastating for the drought-stricken city.

EPA officials said effects to the drinking water supply can be avoided if recovery wells, which are used to remove contaminants, are installed. They also said more modeling should be done and a final report is expected later this year.

Since the contamination is closest to the VA hospital, officials with the New Mexico Environment Department said they have been working on a water protection plan that includes sampling and analysis.

If the toxins reach the hospital well, the department said a contingency plan has been formulated to ensure the hospital has safe and clean water.