The Department of Defense oversees 25 million acres of public lands and 15,897 contaminated sites. This gives the agency the dubious honor of being the nation's leading polluter, says the Project for Participatory Democracy, an initiative of the San Francisco-based Tides Center. Citing the government's poor record on clean-up, the group has produced a legal primer: A Guide to Citizen Law Enforcement: Fighting Environmental Crime at Facilities of the U.S. Departments of Energy and Defense. It is the sixth report on the U.S. uclear weapons complex published by the project. The 38-page guide is written for a lay audience and covers the basics, from investigating to arguing and defending a case. Citizen lawsuits are permitted under the Clean Air Act, the Clean Water Act and the Endangered Species Act, among other federal laws. In June, the booklet was circulated to communities near military bases and nuclear weapons plants. For a copy, send $2 to the Project for Participatory Democracy, 12261'2 State St., Suite 5, Santa Barbara, CA 93101; make checks payable to Tides/PPD. Bulk discounts are available; call 805/962-1707.