Environmentalists are urging federal regulators to limit air pollution from two coal-fired power plants west of Moab, while the plants’ operator says it has already taken steps that go above and beyond the ones that its critics are seeking.

The U.S. Environmental Protection Agency (EPA) is reviewing the State of Utah’s plan to reduce regional haze that often mars the views at nine national parks and wilderness areas in eastern Utah, northern Arizona and western Colorado.

Emissions from four electric-generating units at the Hunter and Huntington power plants in Emery County contribute to poor visibility at places like Arches and Canyonlands national parks. In response, groups like HEAL Utah, the National Parks Conservation Association and the Sierra Club want plant operator Rocky Mountain Power to install pollution controls that more than 250 other power plants across the country have already adopted.

Moab resident Wayne Hoskission, who serves on the Utah Chapter Sierra Club’s executive committee, is encouraging residents to write letters or speak out in support of additional controls at Hunter and Huntington.

“I think that technology is certainly warranted,” Hoskisson said. “There should be a requirement on a business that is abusing our clean air to make money.”

Rocky Mountain Power External Communications Director Paul Murphy said his company has already installed selective catalytic reduction (SCR) technology at some of its other coal-fired power plants. But in this case, he said, his company supports the state’s plan, which factors in the April 2015 closure of Rocky Mountain Power’s Carbon Plant near Helper, as well as pollution control upgrades to four units at the Hunter and Huntington plants in 2008.

“It’s a plan that we believe actually reduces more regional haze than what the environmental groups are asking for, without having to ask our customers to pay an extra $700 million on SCRs,” Murphy said.

The controls would specifically reduce emissions of nitrogen oxides – a main ingredient in regional haze.

Pollution from nitrogen oxides not only impacts views; it can pose threats to human health, as well. Nitrogen oxides react with ammonia, moisture and other compounds to form small particles, which can penetrate into sensitive parts of human lungs and cause or worsen respiratory diseases, such as emphysema and bronchitis; they can also aggravate existing heart disease, according to the EPA.

The agency announced that it is considering two options moving forward. It’s proposing to either accept the state’s plan in full, or approve portions of the plan, while rejecting other components.

“It’s an unusual move in some respects, but it really fits within the (National Environmental Policy Act) process,” Hoskisson said. “The fact that they’re willing to do this, rather than just approve the state plan, is actually a step forward in terms of clean air.”

The Sierra Club and a coalition of other environmental groups allege that pollution from the 1,300-megawatt Hunter Plant and 895-megawatt Huntington Plant is responsible for 40 percent of all nitrogen oxide emissions from Utah’s power sector. Since Moab is directly downwind of both plants, they say that improvements to both plants would go a long way in cleaning up the air locally.

They point to studies which show that human-caused regional haze affects visibility at Arches and Canyonlands national parks 83 percent of the time, compared to average levels of naturally occurring haze.

Generally speaking, the impacts of regional haze extend far beyond Moab. The EPA reported that views at national parks in the West have been reduced from 140 miles to between 35 and 90 miles – mainly as a result of human-caused haze.

Utah’s air quality division first came up with its own plan to control regional haze in 2008. Four years later, the EPA approved a majority of the state’s plan. However, it rejected portions that dealt with nitrogen oxide and particulate matter pollution from the Hunter and Huntington units, forcing the state to go back to the drawing board.

As the EPA reviews the state’s latest plan, HEAL Utah Executive Director Matt Pacenza said the best path it can take is to ensure that Utah’s “biggest polluters” are retrofitted with modern controls.

“We owe it to Utah’s visitors to take every reasonable step to ensure they can enjoy our gorgeous vistas,” Pacenza said. “We owe it to Utah’s families to take advantage of technology that will help them breathe easier.”

If the EPA accepts the state’s plan as is, Murphy said it is not fair or accurate to say that air pollution from the two plants would continue “unabated.”

“The state has an interest in reducing emissions, and they have an interest in reducing pollution,” Murphy said. “In this case, (state officials) agree that the environmental groups are simply wrong.”

The two plants, he noted, have already installed low-nitrogen oxide burners and “baghouses” that capture pollutants.

“Both of them are reducing a lot more emissions than they ever were before,” Murphy said.

Former Utah Division of Air Quality environmental scientist Colleen Delaney, who worked extensively on the state’s plan up until her recent retirement, said earlier in 2015 that those upgrades led to “very substantial” reductions in emissions of both sulfur dioxide and nitrogen oxides.

According to Delaney, emissions of nitrogen oxides dropped by 50 percent.

Despite those reductions, she said that regional haze during the winter months may remain an ongoing problem in part due to a chemical reaction with naturally occurring ammonia.

“Ammonia levels are very low in southern Utah during the winter, and we think ammonia may be limiting the reaction,” she said in June 2015.

Further reductions will be achieved through the closure of the Carbon Plant, she said.

On average, the plant burned 657,000 tons of coal annually, compared to 4.5 million tons that the Hunter Plant burns through in an average year. However, state researchers found that the Carbon Plant released more than 8,000 tons of sulfur dioxide and 3,342 tons of nitrogen oxides per year, according to the Utah Division of Air Quality.

“Even though its electrical generating capacity is much less, (Carbon’s) emissions (were) actually much higher,” Delaney said.

Hoskisson disputes the state’s research, noting the sheer discrepancy in sizes between the Carbon Plant on the one hand and the Hunter and Huntington plants on the other.

“These plants are much larger,” he said.

Rocky Mountain Power only closed the Carbon Plant because it could not bring the 1950s-era facility in line with new federal regulations to limit mercury emissions, he said.

“That was something they needed to do, regardless,” he said. “It really doesn’t count on what they need to do in the future … It’s just not pertinent to what needs to happen.”

Power plant operator says state proposal exceeds environmentalists’ goals

The EPA will be holding a public hearing on its proposals at the Salt Lake City Main Library, 210 E. 400 South, on Tuesday, Jan. 26, 2016. For more information, or to comment on the proposal, go to www.regulations.gov. Enter docket number EPA-R08-OAR-2015-0463.