DOD policy defined an operational range as an area used to conduct research, develop and test military munitions, or train military personnel. Operational ranges were considered active when regularly used for range activities, and inactive when not currently used but still under military control and available for use as a range. Once a range is closed, DOD is required to identify, assess, and clean up or take other appropriate action in response to contamination by military munitions. As such, DOD’s current inventory of operational ranges represents a potential liability for future cleanup. Figures 1, 2, and 3 show examples of the types of ordnance and explosives that can be found on operational ranges. Section 313(a)(1) of the National Defense Authorization Act for Fiscal Year 2002 required DOD to provide Congress with a comprehensive assessment of unexploded ordnance, discarded military munitions, and munitions constituents at current and former DOD facilities. The law required the assessment to include an estimate of the aggregate projected cost of remediation (or cleanup) at operational ranges, to be presented as a range of costs including a low and high estimate, and delivered to Congress in 2003 in DOD’s report on the Defense Environmental Restoration Program. In April 2003, DOD reported its estimate for the total cost to address the potential liability associated with unexploded ordnance, discarded military munitions, and munitions constituents at operational ranges to be between $16 billion and $165 billion. To provide Congress with estimated costs to clean up operational ranges, DOD used inventory data available at the time of its April 2003 report, which counted 10,444 operational ranges located in the United States and its territories. At the direction of Congress, only operational ranges in the United States and its territories were to be considered for the purpose of estimating cleanup costs. According to DOD, these cost estimates were supported by individual service estimates, which in turn were supported by summary information on the number of operational ranges and acreage assumed to contain a high density of unexploded ordnance and munitions constituents—such as target areas, detonation sites, and demolition areas—and the percentage of acreage assumed to contain a low density of contamination from unexploded ordnance and munitions constituents, such as buffers, training areas, and maneuver areas. The services continued to inventory operational ranges under section 366 of the National Defense Authorization Act for Fiscal Year 2003, which required DOD to inventory operational ranges to address training range sustainment and encroachment concerns and submit the inventory to Congress as part of the President’s fiscal year 2005 budget request early in calendar year 2004. The scope of this inventory effort addressed operational range training and testing capacities and capabilities, and specific constraints on the use of operational ranges, but did not specifically include data on the cleanup of unexploded ordnance, discarded military munitions, or munitions constituents. We previously reported that the two key data needed to develop operational range cleanup costs were (1) an accurate and complete operational range inventory and (2) a consistent methodology for estimating costs. Reliable cost estimates can be critical information for DOD and Congress when considering the potential benefits of closing operational ranges or entire installations versus the potentially very high cost of cleaning up such sites. However, such estimates must be based on accurate data that, in the case of operational ranges, begins with a complete and accurate operational range inventory. The costs for cleaning up ranges can be extensive. For example, DOD estimates it will cost $22.6 million to clean up Fort McClellan in Alabama, recommended for closure under DOD’s base realignment and closure program in 1995, and $247 million to clean up Fort Ord in California, closed in 1994. DOD officials explained that wide variations in cost can be attributed to a number of factors, such as future land use, technical complexities, and the high level of difficulty to locate, recover, and destroy ordnance located beneath the ground surface. DOD’s operations at military installations and operational ranges in the United States are subject to laws and regulations governing a variety of environmental concerns, from water quality to the treatment and disposal of hazardous wastes. These laws include the Safe Drinking Water Act, the Clean Water Act, RCRA, the Federal Facility Compliance Act, and CERCLA. DOD is also generally required to comply with state and local environmental statutory and regulatory requirements on its installations and operational ranges. DOD has proposed that Congress specifically exempt it from requirements to clean up unexploded ordnance, munitions, and munitions constituents on operational ranges under RCRA and CERCLA. The Safe Drinking Water Act authorizes EPA to issue national primary drinking water regulations setting maximum contaminant level standards for drinking water that must be met by public water systems. EPA may authorize states to carry out primary enforcement authority for implementing the Safe Drinking Water Act if, among other things, the state adopts drinking water regulations that are no less stringent than the national primary drinking water regulations. EPA has set standards for approximately 90 contaminants in drinking water, including microorganisms, organic chemicals, inorganic chemicals, disinfectants, disinfection byproducts, and radioactive substances. None of the more than 200 chemical contaminants associated with munitions use are currently regulated under the Safe Drinking Water Act. The 1996 amendments to the Safe Drinking Water Act required EPA to establish criteria for a monitoring program for unregulated contaminants (where a maximum contamination level has not been established) and to publish a list of contaminants—chosen from those not currently monitored by public water systems—to be monitored. EPA’s regulation, referred to as the Unregulated Contaminant Monitoring Regulation, was issued in 1999 and supplemented in 2000 and 2001. The purposes of the regulation are to determine whether a contaminant occurs at a frequency and in concentrations that warrant further analysis and research on its potential effects and to possibly establish future drinking water regulations. The first step in the current program required public water systems serving more than 10,000 customers (and a sample of 800 small public water systems serving fewer than 10,000) to monitor drinking water for perchlorate and 11 other unregulated contaminants over a consecutive 12- month period at any point between 2001 and 2003, and report the results to the EPA. Under this regulation, some DOD installations were required to monitor drinking water for perchlorate and other munitions-related contaminants and to report the results. The Clean Water Act authorizes EPA to regulate the discharge of pollutants into waters in the United States. EPA may authorize states to carry out a state program in lieu of the federal program if the state program is at least equivalent to the federal program and provides for adequate enforcement. Under the Clean Water Act’s National Pollution Discharge Elimination System (NPDES) program, facilities discharging pollutants into waters of the United States are required to obtain an NPDES permit from EPA or authorized states. NPDES permits include specific limits on the quantity of pollutants that may be discharged and require monitoring of those discharges to ensure compliance. EPA’s list of the toxic pollutants subject to regulation under the Clean Water Act includes nitrobenzene, a chemical that is on DOD’s list of 20 constituents of greatest concern. RCRA requires owners and operators of facilities that treat, store, and dispose of hazardous waste, including federal agencies, to obtain a permit specifying how their facilities will safely manage the waste. Under RCRA’s corrective action provisions, facilities seeking or holding RCRA permits can be required to clean up their hazardous waste contamination. The corrective actions can be specified in the facility’s operating permit, in a separate corrective action permit, or through an enforcement order. EPA also has authority under RCRA to order a cleanup of hazardous waste when there is an imminent and substantial endangerment to public health or the environment. EPA may authorize states to administer their own programs in lieu of the federal program, as long as these programs are equivalent to and consistent with the federal program and provide for adequate enforcement. EPA’s regulations define hazardous wastes to include those that are specifically listed in the regulations as well as those that are “characteristic wastes.” Characteristic hazardous wastes are defined as wastes that are ignitable, corrosive, reactive, or toxic. A federal district court in California recently ruled, in part, that perchlorate is a hazardous waste under RCRA because it is ignitable. Under section 107 of the Federal Facility Compliance Act of 1992, EPA was required, in consultation with DOD and the states, to issue a rule identifying when military munitions become hazardous waste under RCRA, and to provide for protective storage and transportation of that waste. Under the rule issued by EPA, military munitions are subject to RCRA when, among other things, (1) unexploded munitions or their constituents are buried or otherwise disposed of, or (2) when used or fired munitions are taken off-range. CERCLA governs the cleanup of releases or threatened releases of hazardous substances, pollutants, or contaminants. CERCLA’s definition of a hazardous substance includes substances regulated under various other environmental laws, including RCRA, the Clean Air Act, the Clean Water Act, and the Toxic Substances Control Act. Under section 120 of CERCLA, the federal government is subject to and must comply with CERCLA's requirements to the same extent as any nongovernmental entity. DOD’s cleanup under CERCLA section 120 is interrelated with its environmental restoration program under section 211 of the Superfund Amendments and Reauthorization Act of 1986. According to DOD, there are more than 200 chemicals associated with military munitions, and of these, 20 are of great concern due to their widespread use and potential environmental impact. TNT, Propanetriol trinitrate (nitroglycerin), Royal Demolition Explosive, and perchlorate are among the 20.