Pursuant to a congressional request, GAO reviewed the Environmental Protection Agency's (EPA) and other federal agencies' progress in assessing and evaluating federal facilities with potential hazardous waste contamination. GAO found that: (1) as of December 1992, EPA had evaluated 500 of the 823 potentially contaminated facilities on the docket; (2) the backlog of unevaluated federal facilities could result in an increased risk to public health and the environment or expensive rework if agencies do their own cleanup and are later required by EPA to perform additional cleanup; (3) there is no way to estimate how many federal facilities EPA will include on the National Priorities List (NPL); (4) EPA does not know whether unevaluated facilities are more or less contaminated than those already evaluated; (5) EPA concluded in 1987 that it could not meet the legislative deadlines because of resource limitations; and (6) some federal agencies do not view hazardous waste cleanup programs as a high priority and sometimes provide EPA with late or incomplete assessments.