The nation's biggest polluter isn't a corporation. It's the Pentagon. Every year the Department of Defense churns out more than 750,000 tons of hazardous waste--more than the top three chemical companies combined.

Yet the military remains largely exempt from compliance with most federal and state environmental laws. And in 1998 Congress shielded the Pentagon from having to pay out environmental fines and penalties when it gets caught violating the few laws that do govern the military's conduct, such as the Superfund Act. This has led lawyer Jonathan Turley, director of the Environmental Crimes Project at George Washington University, to call the Pentagon the nation's "premier environmental villain."

The EPA estimates that the total liability for the cleanup of toxic military sites will exceed $350 billion, or five times the Superfund liability of private industry. The Clinton administration didn't spend nearly enough to begin cleaning up these sites and didn't keep a very close eye on how the Pentagon spent the money it got. During the Clinton presidency, the Defense Department spent only $3.5 billion a year cleaning up toxic military sites--much of that on studies, not actual work. In 1998, the Defense Science Review Board, a federal advisory committee set up to provide independent advice to the secretary of defense, looked at the problem and concluded that the Pentagon had no clear environmental cleanup policy, goals or program.

If the Clinton program was chintzy, the Bush plan is downright penurious. While Bush aims to boost overall Pentagon spending by $14.2 billion, the administration would slash its environmental remediation program, overseen by the Office of Environmental Cleanup and the Defense Environmental Restoration Program, by more than 7.5 percent. Moreover, the Bush defense plan calls for "new rounds of base closures" to "shape the military more efficiently." Efficiency is usually a code word for sidestepping environmental rules. And that's exactly what the Bush plan aims to do by slashing the "the rules and regulations that now govern the process." The problem is that most of the sites the Bush crowd is anxious to transfer into private or state hands are old bombing and training grounds.

These sites, which total more than 50 million acres, are among the most insidious and dangerous legacies left by the military. They are strewn with toxic bomb fragments, unexploded munitions, buried hazardous waste, fuel dumps, open pits filled with debris, and burn piles. An internal EPA memo from 1998 warned of the looming problem: "As measured by acres, and probably as measured by number of sites, ranges and buried munitions represent the largest cleanup program in the United States."

But the Pentagon dragged its feet, earning a stern rebuke in 1999 from the EPA's assistant administrator, Tim Fields. "For many reasons," Fields said, "it appears that closed, transferred and transferring military ranges are not being adequately addressed in a manner consistent with accepted environmental or explosive safety standards and practices." A new report released on April 9 by the Government Accounting Office exposes the problem in stark terms. The GAO charges that the Pentagon doesn't even have an accurate inventory of its training sites or the kind and amount of munitions used on them. Desperate to keep most of its budget set aside for acquisitions, the Pentagon typically has lied about how much it will cost to clean up the mess on its training grounds. In its fiscal year 2000 budget request, the Defense Department estimated the total liability for dealing with these problems at $14 billion. But the GAO investigators uncovered another internal Pentagon estimate, which places the figure at more than $100 billion. The Navy, for example, has failed to disclose the cost of handling its obsolete nuclear reactors and mounting radioactive waste, which could alone total more than $13.5 billion.

When a site gets too polluted, the Pentagon has chosen simply to close it down and turn it over to another federal agency. Over the past couple of decades, the Pentagon has transferred more than 16 million acres, often with little or no remediation. The former bombing areas have been turned into wildlife refuges, city and state parks, golf courses, landfills, airports and shopping malls.

Serious contamination of streams, soil and groundwater is a problem at nearly every military training ground. The sites are often saturated with heavy metals and other pollutants as well as unexploded ordnance. The GAO list of the kinds of unexploded munitions left behind on many training sites reads like a catalogue for a Middle East arms show: "hand grenades, rockets, guided missiles, projectiles, mortars, rifle grenades, and bombs."

Many of these former training grounds are located near growing communities. In fact, the recently closed Lowry Bombing Range outside of Denver is adjacent to a site where the Cherry Creek School District is planning to construct two schools and a football stadium. The Forest Service has been forced to close thousands of acres it has acquired from the Army because of the presence of live ordnance. In 1999, a hiker in a Colorado national forest stumbled across an unexploded bomb at Camp Hale, a site used for training mountain troops during World War II and since transferred to the Forest Service. The following year, five live rifle grenades were found near the same site.

A September 1999 EPA report looked at 61 current or former Pentagon training bases and found that there had been "unexploded ordnance incidents" on 24 sites, including "five accidental explosions, which resulted in two injuries and three fatalities."

Confronting the military about its behavior is never an easy task because it is shielded from most legal challenges. But grassroots groups such the Rural Alliance for Military Accountability in Reno, Nevada have reined in some of the more egregious practices, such as open burning of toxic munitions dumps. One of their few consistent allies in Congress has been Sen. Paul Wellstone (D-Minnesota), who has vowed to make the military reveal the extent of its environmental liability prior to closing bases and bombing ranges. "When we close our bases and leave behind environmental contamination," Wellstone says, "the people who suffer are almost always people already living in poverty and already struggling to maintain good health. They do not also need to contend with a toxic legacy left by the U.S. military."