Federal agencies have little data on the costs and benefits of environmental reviews required by the National Environmental Policy Act, even though thousands of projects requiring the reviews are high-profile and expensive, according to a new report by the Government Accountability Office.

NEPA requires reviews for any project that will have an environmental impact, such as roads, docks and drilling projects.

Some reviews are routine and need only a "categorical exclusion" or "environmental assessment;" others require costly and time-consuming Environmental Impact Statements, which often take years to complete and cost the government and private companies millions of tax dollars.

"According to [Department of Energy] data, the average payment to a contractor to prepare an EIS from calendar year 2003 through calendar year 2012 was $6.6 million, with the range being a low of $60,000 and a high of $85 million," the report said.

These expensive reviews are also used in lawsuits filed against a proposed project, meaning agencies have an incentive to create a "litigation-proof" EIS, GAO noted.

There are about 100 NEPA lawsuits each year, and the government prevails in most cases, according to GAO.

The Council on Environmental Quality "has observed that such an effort may lead to an increase in the cost and time needed to complete NEPA analyses but not necessarily to an improvement in the quality of the documents ultimately produced," the report said.

The costs vary widely from agency to agency, and are difficult to separate from the cost of other environmental requirements stemming from the Clean Air Act and related laws and regulations.

The Environmental Protection Agency, which reviews all EISes, tracks some data for the reviews, such as the number of EISes produced each year.

But "EPA officials also told us that there is no governmentwide mechanism to track the costs of completing EISs," the GAO said. "Similarly, most of the agencies we reviewed do not track NEPA cost data."

The smaller reviews are even more difficult to track, because many are routine and may not even be counted as separate reviews.

As a result, there is no reliable government-wide information on how much NEPA reviews and compliance actually cost agencies.

Meanwhile, the benefits of NEPA are even harder to track, GAO said, calling them "mostly qualitative."

NEPA "has been identified by critics as a cause of delay for projects because of time-consuming requirements and praised by proponents for, among other things, bringing public participation into government decision making," the report said.

"We have previously reported that assessing the benefits of federal environmental requirements, including those associated with NEPA, is difficult because the monetization of environmental benefits often requires making subjective decisions on key assumptions," the report added later.

"Costly, abusive lawsuits and endless government red-tape caused by NEPA harm new job creation, and there is a clear need to improve and modernize the law to ensure environmental reviews are completed in an efficient and timely manner so responsible decisions can be made on projects that will lead to new jobs and a growing economy,” said Doc Hastings, the Washington state Republican who is chairman of the House Natural Resources Committee. He was among the House members who requested the GAO report.