They say air pollution from the plant is marring views at Grand Canyon National Park even after the power station underwent improvements in the 1990s. But the owners of the plant contend it is one of the cleanest in the West and that further reductions in pollutants are scheduled.
The National Parks Conservation Association, Sierra Club, Grand Canyon Trust, San Juan Citizens Alliance, To Nizhoni Ani and Dine CARE filed a petition with the Interior Department on Tuesday seeking to have Interior and the Environmental Protection Agency require state-of-the-art pollution devices on the Navajo Generating Station.
The 2,250-megawatt plant is one of the larger coal-fired plants in the country and employs 545.
A similar petition filed a decade ago by conservation groups resulted in the EPA requiring new controls at the Mohave Generating Station in Laughlin, Nev.
The owners of that plant said the improvements were cost-prohibitive and the facility has been shut down.
In essence, the groups are pressing the National Park Service to state that air in the Grand Canyon is not as clean as the Clean Air Act requires in a national park, and that the power plant near Page is one reason why.
The Park Service is already on board, following years of air quality modeling.
"There's ample data that shows that Navajo Generating Station contributes to visibility impairment at the park," said Chris Shaver, chief of the Park Service division that monitors air quality in the nation's parks.
Researchers at the Grand Canyon say smog emitted in Southern California, Las Vegas, and Phoenix also likely contributes to poor visibility in the Grand Canyon.
The ultimate goal is to have the plant convert partly to being run from renewable energy, or to close, said Roger Clark, of the Grand Canyon Trust.
"It's had a good run. It's time to go to pasture," Clark said of Navajo Generating Station, scheduled to operate to 2026.
The power plant discharges 34,000 tons of nitrogen oxides, 1,900 tons of particulate matter and 3,690 tons of sulfur dioxide and 20 million tons of carbon dioxide into the air annually, the groups say in their petition.
They are pressing for expensive, top-notch pollution controls.
But those would not reduce greenhouse gases, like carbon dioxide.
The U.S. Bureau of Reclamation, Salt River Project, Los Angeles Department of Water and Power, Arizona Public Service, Nevada Power, and Tucson Electric Power own the Navajo Generating Station, which generates enough electricity to supply more than 500,000 homes in Arizona, Nevada and California and pump Colorado River water to Phoenix via the Central Arizona Project.
Operating costs for the plant, located on the Navajo Nation, run $200 million annually, not including coal purchased from the Kayenta Mine and Peabody Coal to feed it.
The plant is also supplied with a little less than 27,000 acre-feet of water per year from Lake Powell or more than twice as much water as the city of Flagstaff consumes annually.
The owners of Navajo Generating Station spent more than $400 million in the 1990s to greatly cut some of the farthest-traveling air pollution from the plant, under pressure from the Grand Canyon Trust and the EPA.
SRP calls the plant, operating since 1974, among the cleanest coal-fired power stations in the West.
"The emissions at Navajo Generating Station are at rates that are comparable to what have been set for new plants," said Kevin Wanttaja, manager of environmental services at Salt River Project, which operates the Navajo Generating Station.
The utility plans to add more equipment to remove nitrogen oxides, Wanttaja said, but the groups filing the petition say that doesn't go far enough.
"Maybe it will need to shut down if it can't be cleaned up, but we think a transition from coal to renewables in the next 10 years is going to have to happen one way or another," said Andy Bessler, of the Sierra Club office in Flagstaff.