The Clean Water Act prohibits the discharge of oil into or upon navigable waters or adjoining shorelines and requires the President to establish regulations to prevent oil spills. The President subsequently delegated this responsibility to EPA. To fulfill this requirement, in 1973, EPA issued its Oil Pollution Prevention Regulation, which outlined actions regulated facilities must take to prevent, prepare for, and respond to oil spills before they reach navigable waters or adjoining shorelines. Under this rule, as amended through 2006, EPA seeks to prevent oil spills from storage tanks at facilities that (1) have an aggregate aboveground storage tank capacity of more than 1,320 gallons or a total completely buried storage capacity greater than 42,000 gallons and (2) could reasonably be expected, due to their location, to discharge oil in quantities that may be harmful into or upon the navigable waters of the United States or onto adjoining shorelines. EPA estimated that about 571,000 facilities were regulated under the SPCC rule as of 2005. Oil production facilities (an estimated 166,000 facilities or 29 percent of the total) and farms (an estimated 152,000 facilities or 27 percent of the total) account for the largest portion of these estimated facilities. The SPCC rule does not require facilities that are covered under the rule to report to EPA that they are covered. Therefore, the agency does not have an inventory of facilities that it regulates under the program. However, facilities are required to report discharges of oil in quantities that may be harmful to navigable waters or adjoining shorelines to the National Response Center (NRC), but EPA does not consider these and other data reliable enough for EPA to determine the number of facilities subject to the SPCC rule that have had oil spills. The SPCC rule is a cornerstone of EPA’s strategy to prevent oil spills from reaching the nation’s waters. The regulation requires each owner or operator of a regulated onshore or offshore facility to prepare or amend and implement an SPCC plan that describes the facility’s design, operation, and maintenance procedures established to prevent spills from occurring, as well as countermeasures to control, contain, clean up, and mitigate the effects of an oil spill that could reach navigable waters or adjoining shorelines. Unlike oil spill contingency plans that typically address spill cleanup measures after a spill to navigable waters or adjoining shorelines has occurred, SPCC plans ensure that facilities put in place containment and other measures—such as regular visual inspection and integrity testing of bulk storage containers—to prevent oil spills that could reach navigable waters or adjoining shorelines. EPA’s 10 regional offices administer an inspection program to ensure compliance with the regulations. EPA proposed revisions to the SPCC rule in October 1991 and February 1993. In addition to clarifying previous regulatory language, these proposed revisions outlined additional requirements for regulated facilities. In December 1997, EPA proposed additional amendments to the SPCC requirements, focusing on measures to reduce the information collection burden on affected facilities. Many, but not all, of the amendments to the rule proposed by EPA in 1991, 1993, and 1997, were made final in July 2002. EPA made over 100 amendments to the rule in 2002, including more than 30 that EPA considers to be major. Several of these amendments changed the scope of the rule’s applicability. For example, the 2002 amendments exempted from the rule containers with a capacity of less than 55 gallons, completely buried storage tanks subject to all of the technical requirements of underground storage tank regulations, permanently closed oil tanks as defined in the regulation, and any facility or part thereof used exclusively for wastewater treatment; and eliminated the provision triggering the requirement for an SPCC plan when any single container has a capacity of greater than 660 gallons but maintained the 1,320-gallon total capacity threshold. The 2002 amendments also added to or changed the language of some definitions in the 1973 rule in order, according to EPA, to clarify which facilities are subject to the rule and facilities’ responsibilities under the rule. For example, according to EPA, the 2002 amendments clarified the following: A “facility” may be as small as a piece of equipment—for example, a tank—or as large as a military base; “oil” includes not only petroleum oil, but such other products as animal fats, vegetable oils, and oil mixed with wastes, other than “dredged spoil”; and what “navigable waters” means for purposes of the rule. The SPCC rule applies to facilities that “use” oil, such as in the operational use of oil-filled equipment. EPA had always considered statements in the existing (1973) SPCC regulations that a facility “should” implement a specific rule provision as meaning that a facility was required to comply with that provision or, if circumstances warranted, undertake alternative methods to achieve environmental protection. As a result, EPA changed “should” to “must” to reflect this understanding and address any confusion that compliance with such provisions was optional. According to EPA, the agency made several of these definitional changes to clarify the types of facilities that are included under the rule and facilities’ requirements. However, many industry sectors consider several of these amendments to be changes to the requirements of the rule rather than clarifications and, in some cases, maintain that they had not previously considered themselves subject to the rule prior to these changes. (A summary of industries’ views on the impacts that these and other amendments to the SPCC rule have had or are likely to have on the regulated community, and our analysis of these views, are included in apps. II and III, respectively.) Several of the rule’s amendments also changed requirements for preparing, implementing, reviewing, and amending SPCC plans. For example, the 2002 amendments to the rule decreased from once every 3 years to once every 5 years, the frequency with which a facility’s SPCC plan must be reviewed; required that the plan include a diagram of the facility, and that completely buried storage tanks located on the facility—otherwise exempt from SPCC rules—be included on the facility diagram; and gave EPA regional administrators the authority to require that any facility within their jurisdiction amend the SPCC plan after on-site review of the plan and extend the period of time for facilities already in operation to amend or complete their plans. Other amendments to the rule in 2002 changed facility requirements regarding the use and testing of containers, piping, and other equipment to prevent or mitigate the effects of oil spills from containers. For example, the 2002 amendments amended the integrity testing requirements for aboveground containers and required brittle fracture evaluation of field-constructed aboveground containers that may have a risk of discharge; added specificity to the description of secondary containment requirements, such as detailing that the containment system, including walls and floors, must be capable of containing oil and constructed so that any discharge from the primary containment system is prevented from escaping before cleanup occurs; and required a facility to conduct periodic integrity testing of containers and piping, in addition to the other requirements—i.e., contingency planning and a written commitment of resources—when the owner/operator determines and clearly explains that the installation of specific secondary containment structures or equipment is not practicable. In December 2006, EPA again made several changes to the SPCC rule, including several major amendments to provide additional burden relief to the regulated industries on specific rule provisions. For example, the scope of the rule’s applicability was changed, potentially reducing the number of facilities under the rule, by excluding motive power containers from the rule’s requirements. In addition, the 2006 amendments also changed requirements for preparing SPCC plans by providing an option for “qualified facilities” to prepare a self-certified SPCC plan instead of one that is reviewed and certified by a professional engineer. The 2006 amendments also decreased some secondary containment requirements to reduce the burden for facilities. For example, the 2006 amendments exempted facilities from having to construct and meet requirements for specific sized secondary containment for mobile refuelers; and allowed facilities to use alternatives to general secondary containment requirements for qualified oil-filled operational equipment, such as preparing an oil spill contingency plan and a written commitment of resources to control and remove discharged oil, and requiring an inspection or monitoring program. Although changes to the rule were finalized in 2002 and 2006, EPA extended the date of compliance in 2003, 2004, 2006, and 2007. Currently, owners and operators of facilities in existence on or before August 16, 2002, must continue to maintain their SPCC plans, and then must amend them to ensure compliance with current requirements, and implement the amended plan no later than July 1, 2009. Facilities beginning operations after August 16, 2002, must prepare and implement a plan by July 1, 2009. EPA made this latest extension to, among other things, allow owners and operators of facilities the time to fully understand the 2002 and 2006 amendments and the further revisions to the rule EPA plans to make in 2008 and to make changes to their facilities and SPCC plans. EPA determined that the 2002 and 2006 amendments constituted significant regulatory actions under Executive Order 12866. For significant regulatory actions, Executive Order 12866 requires agencies to assess the benefits and costs of, and reasonably feasible alternatives to, the planned regulatory action. In response, EPA conducted an economic analysis to provide estimates of the potential costs and benefits of the amendments. In addition, the agency conducted economic analyses of the 2006 amendments, both as proposed in 2005 and as made final in December 2006. EPA’s Office of Solid Waste and Emergency Response conducted these analyses. EPA’s economic analysis of the 2002 SPCC amendments had a number of limitations that reduced its usefulness for assessing the economic trade- offs associated with the amendments.