Colorado’s Michael Bennet is one of seven Senate Democrats who signed a letter last week pressuring the Defense Department to find and clean up water contamination.

“Residents of our states are concerned about exposure, and what this means for their health and safety,” the senators wrote. “We urge your support for programs that address the unregulated and emerging water contaminant.”

The full letter is can be read here.

The Colorado Springs Gazette has reported extensively about how military-grade firefighting foam at Petterson Air Force Base has reached the local water supply. The toxic chemicals, perfluorooctanoate and perfluorooctane sulfonate, are cited by the senators’ letter without citing a specific military installation.

Last year, Air Force officials admitted that contaminated water was emptied into the sewer system, and then into Fountain Creek and the Widefield aquifer, which supplies drinking water to the Security, Widefield and Fountain areas ii El Paso County. The Defense Department has more than 400 installations where the chemicals are used, according to Bennet’s office.

The U.S. Environmental Protection Agency issued health advisories. The toxic chemicals can cause liver damage, low infant birth weight, cancer, immune system dysfunction and other health effects. The letters asks the Senate Appropriations Committee to fully fund a study on the health effects of the chemicals and prder the Defense Department to assess, investigate and clean up its toxins.

Joining Bennet as signatories on the letter are Sens. Patty Murray of Washington, Maria Cantwell of Washington, Jeanne Shaheen of New Hampshire, Maggie Hassan of New Hampshire, Kirsten Gillibrand of New York and Bob Casey of Pennsylvania.

“The scope of the contamination is also just beginning to be understood,” they wrote. “DOD is conducting preliminary site inspections in some areas and residents are eagerly awaiting remediation and water treatment efforts.”