Gov. Andrew M. Cuomo on Wednesday announced that New York state will begin testing wells that are monitoring a toxic plume in Nassau County.

Cuomo says the testing would determine whether the plume has reached as far south as Massapequa. The governor also called on Northrop Grumman and the Navy to allow the Massapequa Water District to obtain access to the monitoring wells.

The Massapequa Water District has requested access to ensure that the only origin of the plume is the Grumman site.

The move follows Sen. Charles Schumer's call for action on Monday.

"Start sharing the information about potentially carcinogenic chemicals that show up in nearby monitoring wells," he demanded.

The Navy says it is willing to work with Massapequa Water District to develop a sampling and analysis plan. Northrop Grumman and the Navy are ultimately responsible for monitoring and removing toxins from the underwater plume.

Solvents from the old Grumman site in Bethpage were found in the underground drinking water supply. Those chemicals have been linked to cancer, officials say.