DALE WETZELBISMARCK, N.D. (AP) â¿¿ Gov. Jack Dalrymple, Attorney General Wayne Stenehjem and a group of energy executives argued with environmental activists Thursday about the best way to reduce haze from North Dakota's coal-burning electric power plants. The federal Environmental Protection Agency has drafted rules that would require some North Dakota plants to use a method for reducing nitrogen oxide pollution that is costlier than a procedure favored by the state Health Department. The Health Department normally administers federal clean-air rules in North Dakota. The EPA moved to override some of the state's authority after federal and state health officials could not agree on how some power plants should address federal restrictions on pollution-caused haze. At an EPA hearing in Bismarck on Thursday, Dalrymple said the state's plan would cut nitrogen oxide pollution by about half by using technology that has been proven to work in North Dakota's power plants. Most of them use lignite, a type of low-quality coal. The federal agency's proposal would require much most expensive technology. It estimates its plan could cut nitrogen oxide emissions by 90 percent, but Dalrymple and utility executives who spoke at Thursday's hearing said no company that sells the equipment would guarantee its success with North Dakota lignite. In any case, the visual improvement would be barely perceptible to the human eye, the governor said. Stenehjem said the EPA was illegally ignoring the state's own anti-pollution work, and said the state would challenge the agency in court if it pressed ahead to implement the proposed rules. Stenehjem called the duel a "choice between an ill-considered and unnecessarily expensive EPA proposal that produces an inconsequential result, and ... a well-reasoned, scientifically based and economically sound North Dakota proposal that will continue our longstanding commitment to protecting our environment." At a news conference before Thursday's hearing, environmental activists supported the EPA rules, saying the pollution-control approach the agency has advocated has been used successfully in a number of states.