Jump to main content or area navigation.

Contact EPA Pacific Southwest

Pacific Southwest, Region 9

Serving: Arizona, California, Hawaii, Nevada, Pacific Islands, Tribal Nations

Air Actions, Nevada

NOTE: This content is no longer being updated. The most up to date information can be found in Federal Register Notices and Approved Air Quality Implementation Plans in Region 9.

Fact Sheet: Proposed Revision of the Visibility FIP for Nevada

Today's action:

June 29, 2000

  • The Environmental Protection Agency (EPA) is proposing to revise the Nevada federal implementation plan for visibility protection (Nevada Visibility FIP) to include emissions reduction requirements for the Mohave Generating Station (MGS), located in Laughlin, Nevada. The proposed requirements are based on a consent decree entered into by the owners of MGS (Southern California Edison, Nevada Power, Salt River Project, and Los Angeles Department of Water and Power) and the Grand Canyon Trust, the Sierra Club, and the National Parks and Conservation Association. The consent decree resolves the lawsuit brought by the environmental groups against MGS owners for alleged violations of sulfur dioxide (SO2) and opacity limits.
  • Under the terms of the consent decree, MGS owners will install lime spray dryer technology to reduce visibility impairing SO2 emissions from each of the two boilers at the plant by 85%. Each boiler must also meet an SO2 emission limit of .150 lb/mmbtu. MGS owners will also install baghouses to reduce particulate matter emissions and meet an opacity limit of 20%. In addition, new burners will be installed in the boilers to reduce emissions of nitrogen oxides (NOx).
  • The first unit must be in compliance with all pollution control requirements and emission limits by January 1, 2006 and the second unit by April 1, 2006. The compliance deadlines would be accelerated if all current owners of the facility sell 100% of their interest in the plant before December 31, 2002. Prior to the final compliance deadlines, an interim SO2 emissions limit of 1.0 lb/mmbtu and an interim opacity limit of 30% apply to each unit at the facility.
  • EPA believes that adopting the requirements of the consent decree into the Nevada Visibility FIP is an appropriate way to address concerns regarding the impact of SO2 emissions from MGS on visibility impairment at the Grand Canyon National Park (GCNP) and will allow for reasonable progress toward the national visibility goal with respect to such impact. Today's proposed action does not address MGS's contribution to visibility impairment in the form of regional haze. Under EPA's regional haze regulations, the State of Nevada has the responsibility to prepare a SIP that contains a strategy for reducing emissions of air pollutants from sources that contribute to regional haze.


  • EPA promulgated visibility regulations in 1980 requiring states to develop implementation plans for addressing visibility impairment in national parks and wilderness areas. These regulations also provide that a Federal Land Manager (FLM) for a national park or wilderness area may certify the existence of visibility impairment in such an area. If the FLM makes such a certification, the state (or EPA if a federal implementation plan for visibility protection is in place in the state) must analyze the "best available retrofit technology" for any facility, meeting certain criteria, that EPA finds is reasonably anticipated to cause or contribute to that visibility impairment.
  • In 1985 the Department of the Interior (DOI), FLM for the Grand Canyon National Park, certified to EPA the existence of visibility impairment at GCNP. On August 19, 1997, DOI sent a letter to EPA that reaffirmed the 1985 certification of visibility impairment at GCNP and stated DOI's belief that MGS is contributing to that impairment. A federal implementation plan for visibility protection is currently in place in the State of Nevada. Therefore, EPA is responsible for addressing visibility impairment that may be attributed to facilities in Nevada.
  • MGS is a 1580 megawatt coal-fired power plant located in Laughlin, Nevada, approximately 75 miles southwest of GCNP. It was built between 1967 and 1971. It currently emits over 40,000 tons of SO2 per year and is one of the largest point sources of SO2 in the West. MGS is operated by Southern California Edison Company, the majority owner of the plant. The Los Angeles Department of Water and Power, Nevada Power Company, and Salt River Project also own interests in the plant. The coal for the plant comes from the Black Mesa Coal Mine on the Hopi and Navajo Reservations via a 273-mile coal slurry pipeline. The mine, operated by Peabody Western Coal Company, is jointly owned by the Navajo Nation and the Hopi Tribe. Groundwater from an aquifer underlying the Navajo and Hopi reservations provides the water for the slurry pipeline.
  • On June 17, 1999, EPA published an Advance Notice of Proposed Rulemaking (ANPR) which provided background information on Clean Air Act and EPA regulatory requirements for protecting visibility in national parks and wilderness areas, information on the visibility concerns associated with MGS, and a brief summary of the methodologies and results of Project MOHAVE, the study which evaluated the impact of emissions from the MGS on visibility at GCNP. In the ANPR, EPA also asked the public to submit additional information that the Agency should consider before proceeding further to resolve DOI's concerns.
  • Following EPA's publication of the ANPR, the Grand Canyon Trust, the Sierra Club, the National Parks and Conservation Association and MGS owners settled the lawsuit brought by the environmental groups against MGS owners and entered into a consent decree requiring emissions reductions of visibility impairing pollutants. The National Park Service (NPS) then commented, in response to the ANPR, that MGS's compliance with the emission limits contained in the Mohave consent decree would address the concerns expressed in DOI's 1997 letter that SO2 emissions from MGS are contributing to visibility impairment at GCNP. NPS also indicated that adoption of the consent decree provisions into the Nevada Visibility FIP is an appropriate means of resolving these concerns. EPA agrees and is therefore proposing to revise the Nevada Visibility FIP accordingly.
  • Considering the NPS comments and today's proposed action, EPA does not believe that it is necessary to address the issue of "reasonable attribution" or proceed with a BART determination. EPA is not making a decision with respect to whether there is sufficient information to proceed with a "reasonable attribution" finding or to establish a BART emission limitation. EPA is determining that such a decision is not necessary because the NPS has indicated that its concerns regarding the impact of SO2 emissions on visibility impairment will be resolved if the terms of the Mohave consent decree are contained within the Nevada Visibility FIP.

Next Steps

  • The 30-day public comment period will begin when EPA publishes the Proposed Rule in the Federal Register. After reviewing the comments received in response to this proposal, EPA will determine how to proceed with a final rule.

For More Information

Please contact Bruce Polkowsky of the National Park Service at (303) 987-6944.

Top of page

Jump to main content.