State Department Criticized by E.P.A. on Pipeline Report WASHINGTON - The Environmental Protection Agency sharply criticized the State Department's impact statement for the proposed Keystone XL oil pipeline, saying the report failed to adequately consider the climate change impacts of building the pipeline or to realistically assess alternative pipeline routes or modes of transport. In a relatively unusual public squabble between agencies, a top E.P.A. official said in a letter to State Department officials that the department's latest environmental statement for the 1,700-mile pipeline provided "insufficient information" to adequately judge the project, and that the E.P.A. could not sign off on the pipeline unless more complete studies were performed. The letter was one of more than a million documents submitted as part of the public comment phase of the project. At the end of February, the State Department issued an environmental-impact statement for the pipeline, saying there was no conclusive environmental or economic reason not to build the project. The pipeline would carry a heavy form of oil known as bitumen from oil sands formations in Alberta to refineries in Texas. Secretary of State John Kerry is expected to make a recommendation to President Obama on the pipeline later this year. The State Department must determine whether the project is in the national interest because it crosses an international border. The E.P.A. comments cheered environmentalists, who have made stopping the pipeline a major cause. But it was not clear whether it would affect the decision on the project. Cynthia Giles, the E.P.A. assistant administrator for enforcement and compliance, said that the State Department had failed to adequately support its two fundamental conclusions supporting the project - that the climate change effects of building the pipeline would be negligible, and that Canada would develop the oil sands regardless of whether the $7 billion pipeline is built. Ms. Giles said that the State Department significantly underestimated the long-term climate change impact of developing the Canadian oil formations. She also questioned the study's conclusion that Canada would find other modes of transportation - chiefly rail - to ship the oil without a pipeline. Critics of the pipeline have seized upon these two issues as reasons to veto the project. They say that Canadian oil is substantially dirtier than other forms of oil, and that if Canada cannot easily get the oil to the American market, it will slow development of the oil sands. Anthony Swift, a lawyer with the Natural Resources Defense Council, called the E.P.A. report "tremendous," and said it proved that the State Department had not yet adequately considered the wide range of environmental issues that have long concerned the pipeline's opponents. A senior State Department official said the department had been closely working with the E.P.A. to analyze the pipeline's environmental effects and would take the agency's concerns into consideration. Dan Frosch contributed reporting from Denver.