Environmentalists are accusing the U.S. Environmental Protection Agency of dragging its feet on pollution controls for two coal-fired power plants on the Navajo Nation that serve utilities including Tucson Electric Power Co. The National Parks Conservation Association and Dine CARE recently sued the agency and its administrator in federal court to force a firm deadline for action. The EPA gave notice in 2009 that it would be considering whether the Navajo Generating Station in Page and the Four Corners Power Plant in northwestern New Mexico need upgrades to control haze-causing nitrogen oxide emissions. But no final decisions have been made, nor is the EPA under a deadline to do so. The environmentalists contend the longer the EPA puts off a decision, the more it hurts the health of Navajos and Hopis and visibility at places like the Grand Canyon. An EPA spokeswoman said the agency is reviewing the lawsuit and would not comment. The 2,250 megawatt Navajo Generating Station ensures power and water demands are met in Arizona\'s major metropolitan areas. It also contributes significantly to the economies of the Navajo and Hopi tribes. Conservationists see it as a health and environmental hazard. TEP, which generates most of its power from coal, owns a 7.5 percent stake in the Navajo plant and a 7 percent stake in Four Corners. The Navajo power plant already has low-nitrogen oxide burners that its owners said are more than adequate to control emissions. But the EPA could decide to mandate that more expensive technology, such as selective catalytic reduction, be installed.