Water suppliers, community groups and local politicians accused Northrop Grumman of neglect in a letter this week criticizing the defense contractor for allowing groundwater contamination to spread in Bethpage and beyond.

The letter, addressed to Northrop Grumman’s board and shareholders gathering in Falls Church, Virginia, for an annual meeting, said the firm was not standing up to its own espoused values of responsibility.

“Your irresponsible actions, evidenced over decades of neglect, and the duplicitous skirting of your stated corporate responsibilities, have been driven by ‘liabilities on your balance sheet,’ not the lives and health of the people in the community that you have chosen to abandon,” said the letter sent Wednesday by the Bethpage Water District.

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It was signed by water districts in South Farmingdale, Massapequa and Oyster Bay, as well as the Nassau Suffolk Water Commissioners’ Association. The Bethpage Chamber of Commerce and Bethpage Kiwanis club also signed on with Nassau County Legis. Rose Marie Walker (R-Hicksville) and Laura Schaefer (R-Westbury).

“This is a corporation that called Bethpage its home for many, many years,” Walker said. “It was a vital part of Bethpage.”

Northrop Grumman’s actions were akin to it saying, “We’re out of there. What happened in the past is your problem,” Walker said.

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Northrop Grumman spokesman Vic Beck confirmed receiving the letter.

“As always, we appreciate their input and perspective, although it differs substantially from ours,” he said in a statement. “We are reviewing their letter and preparing a substantive response.”

Beck said Northrop Grumman for more than 20 years has worked closely with federal, state and local entities to address “various legacy environmental conditions in the Bethpage area.”

From the late 1930s until 1996, Bethpage was home to a 600-acre sprawling manufacturing and testing facility operated by the Navy and what is now Northrop Grumman.

Operations there produced the Apollo Lunar Module and warplanes like the Hellcat, Tigercat and Bearcat. It also left behind a legacy of contamination dating to the 1940s, was added to the state Superfund program in 1983, and is subject to a number of cleanup plans to remediate soil and groundwater contamination.Several plumes are emanating from the original site. In April, Oyster Bay officials closed Bethpage Community Park, a former legal Northrop Grumman dumping ground, after the state opened a probe into a whistleblower’s report that drums were uncovered in the 1990s and reburied. A plume coming from there is among the most toxic contamination associated with the site.

Late last year a monitoring well for that plume detected 14,700 parts per billion of a mixture of volatile organic chemicals. Chief among the chemicals was a solvent called trichloroethylene, or TCE, which is classified as a likely carcinogen. The drinking water standard for TCE is 5 parts per billion.

The DEC ordered Northrop Grumman in March to speed up construction of a remediation well nearby, saying drinking water was threatened.

The agency that month also ordered Northrop Grumman to open up wells for testing after the Bethpage Water District reported elevated levels of the radioactive element radium in a drinking well that had been closed off from the system since 2013 but the water is still tested.

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“After decades of delays Northrop Grumman and the Navy must clean up this environmental disaster they left behind,” Massapequa Water District Superintendent Stan Carey said.