The U.S. Senate has passed a water infrastructure bill that orders the secretary of the Navy to annually map the movement of groundwater plumes emanating from a former manufacturing site in Bethpage and to project where the toxics may flow.

The provision, which also requires development of a strategy to prevent water supplies from being affected in the future, was included in the Water Infrastructure Improvements for the Nation Act that passed early Saturday on a 78-21 vote and will head to the president for a signature.

“If water is contaminated, people should know,” Sen. Chuck Schumer (D-N.Y.) told Newsday in a phone interview Tuesday. “Neither the Navy nor Northrop Grumman will be able to duck their responsibility anymore. . . . They give us little smidgens here and there, but we don’t know the whole story.”

The Navy and what is now Northrop Grumman operated manufacturing, testing, engineering and research facilities on more than 600 acres in Bethpage between the late 1930s and 1996 to support wartime and space exploration efforts.

Contamination was first documented in the late 1940s, and the sites were added to the state Superfund list in 1983. A number of cleanup plans are in effect to remediate several groundwater plumes and soil contamination.

The toxic brew of volatile organic chemicals — some believed to cause cancer — has spread south as far as four miles from the Bethpage location and hit drinking water wells in Levittown. Local officials say the drinking water supplies for 250,000 residents could ultimately be at risk.

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If the bill is signed, the secretary of the Navy will have to report to Congress about the groundwater contamination within 180 days of the act becoming law and then annually for the next four years. Schumer’s aides said they were confident President Barack Obama would sign the bill.

The Navy did not respond to requests for comment Tuesday.

“I actually think maybe this is a good thing that it made it to the national level now,” said Michael Boufis, superintendent of the Bethpage Water District, which has spent millions of dollars removing contamination and is embroiled in a lawsuit against Northrop Grumman over the groundwater contamination.

The report will have to include a description of contaminants that are leaving the site within a 10-mile radius, the movement of contamination over time, and how drinking water supplies could be affected.

It also requires development of a strategy to prevent contamination from hitting future supplies that may be in the path of the plumes, according to the act.

“For Massapequa that is the most encouraging part,” Massapequa Water District superintendent Stan Carey said.

The district’s wells have not yet been hit by plume contaminants but are thought to be in its path. “It sends a message to the Navy and Grumman: Congress is watching now,” Carey said. “Enough has not been done. They’re accountable now.”

The plume provision, which was written by Schumer, was included after months of working with staff for Sen. Barbara Boxer (D-Calif.) and Sen. James Inhofe (R-Okla.), but the New York Democrat said he could not vote for the overall bill after a section he believed weakened the Endangered Species Act in drought areas was added by the House of Representatives. Boxer is a ranking member of the Senate Environment and Public Works Committee and Inhofe is chairman.

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“Now we will have a full, comprehensive picture,” Schumer said.

Members of the community and the water district have long said recovery updates are piecemeal.

The Navy has community meetings twice a year but they address only contamination the federal agency is handling. Northrop Grumman is also responsible for cleanup but is not required to hold public meetings, though it has recently as the defense contractor sought community support for a series of remediation wells south of Central Avenue.

Schumer’s office said this bill required the Navy to address all contamination no matter the entity working to remove it from soil or groundwater.

“I think it’s going to give everyone more answers,” Boufis said. “I think it’s going to give the community more answers. I think it’s going to give the district more answers.”

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The state Department of Environmental Conservation has pressured Northrop Grumman to speed up construction of a remediation well in Bethpage.

“We applaud the U.S. Congress for directing the Navy to develop this mapping analysis and strategy, which builds on the state’s ongoing comprehensive actions to hold the Navy and Northrop Grumman accountable for the cleanup of the groundwater contamination they caused,” DEC Commissioner Basil Seggos said in a statement.

Earlier this year, the state released an outside consultant’s report that estimated the cost to clean up and contain the plumes would be between $268 million and $587 million. That report is still under review, DEC said.

Assemb. Joseph Saladino (R-Massapequa), who pushed for the bill requiring the study, said he looked forward to the Navy reports. “We hope that the Navy will be very accurate in its depiction of the plume,” he said.