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U.S. Department of the Interior - Navajo Generating Station
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Federal Involvement at the NGS




In This Section:

Navajo Generating Station
Purpose of the Federal NGS Working Group
Stakeholder Involvement
Summary of 2012 NREL Reports

The 2250-MW Navajo Generating Station (NGS) is a coal-fired power plant located on the Navajo Indian Reservation, just east of Page, Ariz., approximately 135 miles north of Flagstaff, Ariz., and within approximately 185 miles of 11 national parks and wilderness areas. The three 750-MW units at NGS have been in operation since 1974. NGS is the largest coal-fired power plant in the western United States and is among the largest single sources of nitrogen oxides (NOx) emissions in the country. The nearby Kayenta Mine, leased from the Navajo Nation and the Hopi Tribe and operated by Peabody Western Coal Company, is the sole source of coal burned at NGS.

There are six participating owner entities of NGS: Bureau of Reclamation – 24.3 percent; Salt River Project (SRP), which also acts as the facility operator – 21.7 percent; Los Angeles Department of Water and Power (LADWP) – 21.2 percent; Arizona Public Service (APS) – 14 percent; Nevada Power Company (NPC) – 11.3 percent; and Tucson Electric Power (TEP) -7.5 percent.

A number of federal agencies oversee federal interests and responsibilities related to NGS, including tribal trust responsibilities. In addition to Reclamation’s participating interest role in NGS, five other agencies of the Department of the Interior (Interior) - National Park Service; Bureau of Indian Affairs; Office of Surface Mining Reclamation and Enforcement; Bureau of Land Management; and Fish and Wildlife Service - have direct roles relating to NGS or the Kayenta Mine. The Environmental Protection Agency (EPA) has a Clean Air Act regulatory role relating to air quality and visibility in the region, which includes promulgating Best Available Retrofit Technology (BART) requirements for NGS. The Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy, Office of Indian Energy Policy and Programs and National Laboratories have technical expertise related to clean energy development and production in Indian country.

The Colorado River Basin Project Act of 1968 authorized construction of NGS as a preferred alternative to building hydroelectric dams in the Grand Canyon to provide power to the Central Arizona Project (CAP). The CAP is a federal water project consisting of NGS and a 336-mile water distribution system that delivers about 1.5 million acre-feet (af) per year of Colorado River water from Lake Havasu in western Arizona, to agricultural water users in central Arizona, and municipal water users in Maricopa, Pinal and Pima counties.

The CAP water is also delivered to Indian tribes in Arizona pursuant a number of tribal water rights settlements and to reduce groundwater usage in the region. Several tribes located in Arizona have allocations of CAP water that were provided under water settlement agreements approved by Congress. In exchange for allocations of CAP water (sometimes at reduced cost) and access to funds for the development of water infrastructure, these tribes have released their senior water rights claims. The Central Arizona Water Conservation District (CAWCD) buys electricity from NGS to power the pumps that move CAP water to its destinations along the distribution system. By 2030, nearly one-half of the 1.5 million af of CAP water will be allocated to Indian tribes and the rest to non-Indian water users.

Excess NGS power owned by Reclamation that is not used by CAP is sold and profits are deposited into a fund (the Lower Colorado River Development Fund) to support the tribal water settlement agreements. Interior (through Reclamation) plays an important role in the implementation of these settlement agreements and the management of the funds set aside for water infrastructure development for tribes.

Royalties and other funds from NGS and the Kayenta Mine paid to the Navajo Nation and Hopi Tribe contribute significantly to the annual revenues for both tribes’ governments. In addition, both NGS and the Kayenta Mine provide employment for hundreds of tribal members.

NGS is located near many of our most treasured national parks and wilderness areas. Congress mandated heightened air quality protection for these areas in designating them as Class I Federal areas under the federal Clean Air Act. Eleven Class I areas are located within approximately 185 miles (300 km) of NGS: Arches National Park (NP), Bryce Canyon NP, Canyonlands NP, Capitol Reef NP, Grand Canyon NP, Mazatzal Wilderness Area (WA), Mesa Verde NP, Petrified Forest NP, Pine Mountain WA, Sycamore Canyon WA and Zion NP. These areas support an active tourism industry that brings approximately $1 billion in economic benefits to the communities around these parks each year.

Air emissions from NGS include particulate matter, mercury and other toxic metals, acid gases, sulfur dioxide (SO2) and NOx. These pollutants cause a number of environmental and human health problems near the plant and downwind. Of particular concern at NGS, given its location, SO2 and NOx combine in the atmosphere to form fine particles which impair visibility.

NGS uses hot-side electrostatic precipitators to control emissions of particulate matter PM and toxic metals, flue gas desulfurization units FGDs to control emissions of SO2, toxic metals and acid gases, and low-NOx burners with separated over-fire air to reduce emissions of NOx. These pollution controls are a significant part of NGS’s strategy for meeting its pollution control requirements under federal and state laws. In 2013, EPA proposed additional NOx control requirements for NGS due to its continued significant impact on visibility in eleven Class 1 areas in Arizona, Utah and Colorado.

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