Canada and the United States have open borders for waste shipments, and waste has flowed across the border in both directions for years. The federal government does not report data regarding such shipments, but information is available from Environment Canada, the Ontario Ministry of the Environment, and from some U.S. states. According to these sources, the United States appears to be a net exporter to Canada of hazardous waste; but, because of plentiful landfill capacity, low-cost disposal options, and existing contractual arrangements, the United States is a much larger net importer from Canada of non -hazardous solid waste. The latter category can include municipal solid waste (MSW), construction and demolition (C&D) waste, medical waste, and non-hazardous industrial waste. Under a 1986 agreement between the United States and Canada, shipments of hazardous waste require notification to the importing country and that country's consent before waste may be shipped. The notification must include the exporter's identity; a description of the waste; the frequency or rate at which the waste will be imported; the total quantity of the waste; the point of entry; the identity of the transporter, means of transport, and type of containers; the identity of the consignee; a description of the manner in which the waste will be treated, stored, or disposed; and the approximate date of the first shipment. The receiving country is given 30 days from the date it receives notice to indicate its consent (conditional or not) or its objection to the shipment. If no response is received within the 30-day period, the importing country is considered to have no objection. Consent is not irrevocable: whether express, tacit, or conditional, the importing country's consent may be withdrawn or modified for good cause. The bilateral hazardous waste agreement was amended in 1992 to establish similar requirements for municipal solid waste, but, for lack of legislative authority, the amendment was never implemented. It is these unregulated shipments of non-hazardous waste, principally municipal solid waste, that have proven controversial. Lacking notification or consent requirements for MSW, many state governments do require the operators of solid waste management facilities to report the origin of waste they have received for disposal after the fact, on a quarterly or an annual basis. According to these data, entities in the Canadian province of Ontario have shipped major quantities of waste (principally MSW and C&D waste) to the United States in recent years. State waste reporting requirements are not uniform: the reporting periods vary, as do the methods used by states to collect the data; some states don't collect data at all, although one can often find a knowledgeable official willing to provide an estimate. Using these sources, CRS has from time to time compiled the existing state data, in an attempt to provide comprehensive and comparable estimates. Our latest survey, published in June 2007, indicated that Michigan received 3,781,171 tons of municipal solid waste from Ontario in FY2005 (October 2004-September 2005). New York, the second largest recipient, received 195,228 tons from Ontario in calendar year 2005. The only other recipient we identified was the state of Washington, which received 101,834 tons from the Canadian province of British Columbia in 2005. The proportions are consistent with amounts reported in earlier years. Thus, it appears that more than 90% of the solid waste that Canada ships to the United States has gone to Michigan. The remainder has generally gone to the states of New York and Washington. While somewhat controversial throughout the 1990s, Canadian waste imports have received much greater attention since late 2002, when the city of Toronto—Canada's largest city—announced that it would close its last landfill and begin shipping all of its waste to Michigan. Canada's shipments of waste to Michigan increased 83% between then and fiscal year 2006. In FY2006, Michigan reported that it received 12,084,907 cubic yards (an estimated 4.03 million tons) of non-hazardous waste from Canada. Canada accounted for 19.5% of all the waste disposed in Michigan landfills in that year. Canadian waste imports decreased 9% in FY2007, to 10,982,984 cubic yards (about 3.66 million tons), but still accounted for 18.9% of the waste disposed in Michigan landfills. Since the late 1980s, Michigan has attempted to restrict imports of waste. In 1992, however, in Fort Gratiot Sanitary Landfill v. Michigan DNR , waste import restrictions authorized by the state were held unconstitutional by the U.S. Supreme Court. Under Article I, Section 8 of the U.S. Constitution, Congress is given power to regulate interstate and foreign commerce; in a long series of cases beginning in the 1800s the Court has held that this grant of authority to Congress implies a prohibition of state actions to discriminate against interstate and foreign commerce, absent the consent of Congress. Providing congressional consent is the goal of numerous bills that have been introduced in Congress. In the 109 th Congress, the most prominent of these bills was H.R. 2491 (Gillmor), which was reported by the House Energy and Commerce Committee on September 27, 2005, and passed the House by voice vote, September 6, 2006. Similar legislation ( H.R. 518 ) was introduced by Representative Dingell in the 110 th Congress, was reported by the Energy and Commerce Committee ( H.Rept. 110-81 ) March 29, 2007, and passed the House by voice vote, April 24, 2007. As of January 2008, there has been no action on the bill in the Senate. H.R. 518 would implement the bilateral U.S.-Canada waste trade agreement, as amended in 1992 to deal with municipal solid waste shipments between the two countries. It would require the EPA Administrator to perform the functions of the Designated Authority under the agreement and require him to implement and enforce the agreement's notice and consent requirements. In considering whether to consent to waste importation, the EPA Administrator would be required, in the words of the bill, to "give substantial weight to the views of the State or States into which the municipal solid waste is to be imported, and consider the views of the local government with jurisdiction over the location where the waste is to be disposed." The Administrator would also be required to consider the impact of the importation on continued public support for and adherence to state and local recycling programs, landfill capacity, and air emissions and road deterioration from increased vehicular traffic, and to consider the impact of the importation on homeland security, public health, and the environment. The bill would also authorize states to restrict imports of foreign MSW, provided they do so prior to the bilateral agreement's implementation. Under the latter provision, states would have a window of up to 24 months after the bill's enactment to impose restrictions of their choosing on the receipt of foreign MSW, and those regulations could remain in effect as long as the state desires. Michigan has already enacted legislation that would go into effect if this provision of H.R. 518 were enacted. On March 9, 2006, the Governor signed H.B. 5176, which prohibits the delivery and acceptance for disposal in Michigan of MSW generated outside of the United States, once Congress authorizes such prohibitions. In the 109 th Congress, H.R. 5441 , the Department of Homeland Security (DHS) FY2007 Appropriations bill, as amended by the Senate July 13, 2006, also contained provisions that would have discouraged Canadian waste imports. An amendment submitted by Senator Stabenow (for herself, Senator Levin, and Senator Baucus) provided for inspections of international shipments of MSW, and required the Secretary of Homeland Security to levy a fee to cover the approximate cost of such inspections. In a floor statement, Senator Stabenow explained the effect of the amendment as follows: Based on information provided by the inspector general [of the Department of Homeland Security], we know that it will take four Customs agents about 4 hours for each trash truck inspection. Based on personnel and administrative costs, we estimate that the fee for each trash truck will be approximately $420. A separate amendment, introduced by Senator Levin (with the co-sponsorship of Senators Stabenow and Voinovich) and also approved in the Senate by unanimous consent, would have required that the Secretary of Homeland Security deny entry into the United States to trucks carrying MSW unless he certifies to Congress that the methodologies and technologies used by the Bureau of Customs and Border Protection to detect the presence of chemical, nuclear, biological, and radiological weapons in municipal solid waste are as effective as those used to screen for such materials in other items of commerce entering the United States in commercial motor vehicles. Following passage of the Stabenow and Levin amendments, on August 30, 2006, the Ontario Ministry of the Environment reached an agreement with the two Senators, under which Ontario will eliminate shipments of municipally managed waste to Michigan by the end of 2010. In return, the Senators agreed not to pursue passage of the inspection fee and certification provisions in the Homeland Security Appropriations bill or to "pursue similar current or future measures." The inspection fee and certification provisions were deleted in conference, and the bill was signed by the President October 4, 2006. On September 19, 2006, Toronto's City Council approved a letter of intent to purchase a landfill near London, Ontario, where it is expected to ship its waste as it phases out shipments to Michigan. In FY2007, shipments of solid waste from Ontario to Michigan declined for the first time since FY1999. The steps taken by Congress in beginning to move legislation, as well as the separate legislation enacted by the state of Michigan, clearly played a role in bringing about the exchange of letters with Ontario. But large issues remain. Issues remaining to be addressed include some posed by the exchange of letters and others posed by H.R. 518 .