The Department of Defense will help fund investigations for two sites in the Tucson area thought to be connected to groundwater contamination issues that have plagued parts of the city for years.

The Defense Department says both the Davis-Monthan Air Force Base and the Morris Air National Guard facility are green-lit to move forward on expedited investigations into contamination issues with PFAS. The human-made chemicals are linked to health issues like cancer and are also part of a firefighting foam used for years at air bases and airports.

The facilities are two of a total 30 sites across the U.S. considered critical enough to require investigation and remediation plans.

City officials say the designation is important because it allows other federal actions — like Superfund designations and funding — to move forward more quickly. Municipal water authorities have spent the last several years monitoring various wells for PFAS contamination and are now also getting state and federal aid to build facilities to treat effected water.