For 34 years, communities around the Nassau County town of Bethpage have been wary of their drinking water thanks to the so-called "Grumman Plume." Long considered one of New York's most pressing environmental crises, the miles-long plume of contaminated groundwater sources has stoked fears of cancer and other illnesses in communities living in the shadow of the former aerospace giant's Long Island facility.

Now, new evidence suggests that Grumman and government regulators knew about the problems caused by the pollutants decades before it became public.

A trove of documents uncovered by Newsday has revealed that the company knew it was polluting the region's groundwater supply as early as the 1950s, while continuing to publicly deny any liability. According to investigative reporter Paul LaRocco, that lack of transparency slowed down clean-up attempts while the plume was still in its infancy.

"It's caused a lot of stress and worry for residents in that area in recent decades as it has continued to grow without a comprehensive plan to contain and eliminate the contaminants," LaRocco told WNYC host Sean Carlson.

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