Before its closure, the Mohave Generating Station annually dumped more than 40,000 tons of sulfur dioxide and 10,000 tons of soot and smoke into the region's air. © by Rick Moore

The owners of Mohave, which closed on December 31, 2005, have indicated that the plant will remain shut down, at least temporarily, due to non-compliance with a 1999 consent degree that required the owners to either install pollution controls by December 31, 2005 or shutter the plant.   In addition, negotiations for new coal and water use contracts with the Navajo and Hopi people (necessary to continue to mine coal and use tribal water to transport it) have been unsuccessful.  The two tribes share ownership of Black Mesa where the coal is mined and mixed into a slurry using approximately 4,500 acre feet of groundwater before it's then pumped through a 273-mile pipeline to the power plant.  The plant uses a maximum of 18,240 tons of coal per day with both units running at full capacity.

The 2002-03 average emissions for the power plant are shown in Table 1 below.  Air pollution from Mohave presents several problematic issues.  Sulfates, caused by sulfur dioxide emissions, are the single largest contributor to the haze and reduced visibility that visitors experience at the Grand Canyon and 27 other national parks, national monuments, and wilderness areas in the Four Corners region downwind from Mohave Generating Station.  On February 8, 2002, the Environmental Protection Agency published its final rule on Mohave for revising its federal implementation plan to protect visibility at Grand Canyon. However, it was emission reductions ordered by the 1999 consent decree that the new rule referenced in achieving the new standards to protect visibility.

Table 1. 2002-2003 averaged emissions for Mohave Generating Station units 1 and 2.

In 1998, the Grand Canyon Trust, Sierra Club, and National Parks and Conservation Association filed a lawsuit against the owners of Mohave. In a comprehensive review of the plant’s operations, the plaintiffs alleged that it routinely violated its opacity limits (a measure of plume density) and that the owners claimed exceptions to these limits during startup and shutdown that were not included in Nevada’s operating permit. They further alleged that the State of Nevada had undermined Clark County’s attempt to require that Mohave dramatically reduce its sulfur emissions. These violations, the lawsuit argued, also threatened the health of people who lived near the plant. Residents testified to “chocolate skies,” “enormous puffs of soot-black smoke,” and “the smell of sulfur on windless days.”

While the lawsuit worked its way through federal court, the plaintiffs met for several months with Mohave’s owners to negotiate a settlement. The court-accepted consent decree was signed on December 15, 1999. It provided six years for renegotiating coal and water contracts and for installing pollution controls at the power plant that would significantly reduce its nitrogen, sulfur, and fine particle emissions. Unfortunately, at this time, the owners have not fulfilled any of the agreements negotiated in the consent decree.

The closure of Mohave Generating Station is as unprecedented as some of its related operations. Its coal slurry delivery system is unique, using pristine groundwater pumped from beneath the arid Navajo and Hopi reservations for industrial use.   And, in spite of the fact that the tribes have sued multiple times to resolve their claims of undervalued coal royalties, the price paid by the mining company to the tribes for coal remains well below market rates. Nonetheless, those royalties provided $20 million in annual income to the tribes in previous years. The loss of those royalty revenues, combined with job losses at Black Mesa mine and other related revenues, will inflict severe economic pain in a region where chronic unemployment exceeds 40%.

Benefits of Mohave’s closure include cleaner air and better respiratory health for those living near the power plant.   In addition to ending groundwater pumping to slurry coal, the plant will no longer gulp 16,000 acre feet of water annually from the Colorado River to use in its boilers and cooling towers.  In addition, the grandeur of the Grand Canyon and other parks and monuments in the region will be more visible to visitors thanks to cleaner air.

Most important, the closure of Mohave may offer an unprecedented opportunity to begin the shift from older, dirtier energy technologies to the next generation of cleaner energy.  For example, Mohave's owners will receive "windfall" revenues from the sale of sulfur allowances from the shuttered plant.  Acid-rain, cap and trade provisions of the 1990 Clean Air Act amendments allow Mohave owners to sell approximately 50,000 tons of sulfur allowances. Currently valued at more than $1000 per ton, the sulfur allowances will provide approximately $50 million in annual revenue to the owners.  Revenue in that amount might be considered by the owners as the start of an investment account that is dedicated to creating new, renewable energy options for the future.  If those investments were made in partnership with the Navajo and Hopi people, they could also serve as restitution and provide a just transition for their future.

GCT Links
Consent Decree
February 2002: EPA Nevada Visibility/Mohave Rule

Non-GCT Links
Southern California Edison
Sierra Club
National Parks Conservation Association
Final Project MOHAVE Report

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