WASHINGTON—The number, duration and complexity of Superfund lawsuits declined nearly 50% from 1994 to 2007 as the U.S. Environmental Protection Agency changed enforcement tactics to encourage earlier settlements and as fewer sites were listed on the National Priority List, according to a Government Accountability Office report.

Litigation also declined because the courts clarified several uncertainties in the law, allowing parties to become more certain of the probable outcomes before pursuing litigation, the report concluded.

While the EPA added more than 400 sites to the priority list in fiscal year 1983, it added an average of just 20 sites per years in fiscal years 1998 through 2007, according to the July report “Superfund: Litigation Has Decreased and EPA Needs Better Information on Site Cleanup and Cost Issues To Estimate Future Program Funding Requirements.”

Although the number of sites added to the priority list has declined since the launch of the Superfund program, it is becoming increasingly difficult for the agency to forecast future program costs because of the changing nature of sites being listed, the GAO report noted.

For example, more mining sites, which are among the most expensive types of sites to clean up, are being added to the list. Moreover, because of limitations in the EPA’s data, it is difficult to determine which of these sites have viable responsible parties from which to recover cleanup costs, according to the report.

Between 1994 and 2007, the EPA’s enforcement actions resulted in an estimated $29.9 billion in cleanup cost recoveries, commitments to conduct site work and other outcomes, according to EPA estimates. Nearly 80% of the EPA’s completed enforcement actions at National Priority List sites resulted in agreements with responsible parties to either perform or pay for site cleanup work, it said.

To read the full report, go to www.gao.gov/new.items/d09656.pdf.