Summary: GAO discussed the Environmental Protection Agency's (EPA) and state oversight and enforcement of federal facilities' compliance with the National Pollutant Discharge Elimination Program. GAO found that: (1) 30 of the 150 major federal facilities were not in compliance with the program requirements; (2) major federal facilities' noncompliance rate was twice that of nonfederal facilities; (3) over 40 percent of all violating federal facilities were noncompliant for a year or longer; (4) most of the noncompliance was due to the low priority that facilities gave to correcting violations; (5) EPA and state regulators did not take timely enforcement actions against federal facilities; (6) EPA did not have adequate oversight of its regions' or states' enforcement at the facilities; and (7) EPA did not have criteria for consistent follow-up on facilities that were not issued enforcement orders or for verifying information received from regions on facilities that were not issued enforcement orders. GAO believes that EPA should: (1) improve its oversight of regional and delegated state enforcement activities; (2) establish follow-up criteria for timely enforcement action; and (3) obtain compliance agreements for federal facilities that were not issued timely enforcement actions.