U.S. EPA FACT SHEET

Supplemental Proposal

Best Available Retrofit Technology (BART) for Navajo Generating Station, Navajo Nation

September 25, 2013

Summary of Action

In today’s Supplemental Proposal, EPA is proposing an additional Alternative to BART 

submitted on July 26, 2013 by a group of stakeholders, known as the Technical Work Group 

(TWG). The TWG Alternative would establish a lifetime cap in NOx emissions over 2009-2044 

that would ensure cumulative NOx emissions from NGS are below that level. EPA has 

independently evaluated the TWG Alternative and is proposing to determine that the TWG 

Alternative is “better than BART” because maintaining emissions below the 2009-2044 NOx Cap 

achieves greater reasonable progress than BART towards the national visibility goal. EPA is 

currently taking comment on this alternative as well as the proposed BART and “better than 

BART” alternative contained in our February 2013 proposal.

Background On Today’s Proposal

 EPA is proposing to reduce harmful nitrogen oxide (NOx) emissions from the Navajo 

Generating Station (NGS), one of the largest sources of NOx emissions in the country. 

These pollutants contribute to visibility impairment in 11 national parks and 

wilderness areas surrounding NGS, including the Grand Canyon which is less than 20 

miles away from the plant. See map.

 On February 5, 2013, EPA proposed a Best Available Retrofit Technology (BART) 

determination for NGS, an Alternative to BART, and a framework for evaluating 

Alternatives to BART that provide greater flexibility in the timeframe for compliance 

in exchange for greater emission reductions. EPA invited stakeholders to suggest 

additional Alternatives to BART that meet our proposed framework. The July 26, 

2013 TWG Alternative was submitted to meet this framework.

 The TWG is composed of Salt River Project, the U.S. Department of the Interior, the 

Navajo Nation, the Gila River Indian Community, Environmental Defense Fund, 

Western Resources Advocates, and the Central Arizona Water Conservation District.

 EPA is accepting comment concurrently on today’s Supplemental Proposal and our 

proposal from February 5, 2013. The public comment period will close on January 6, 

2014.
 Emissions Reductions:

Over the lifetime of the facility (2009-2044) the TWG Alternative will result in 

greater NOx emission reductions than our proposed BART determination. EPA’s 

proposed BART determination would reduce emissions by over 84 percent, or a total 

of 28,500 tons per year.

 Visibility Improvements:

These emission reductions will result in perceptible visibility improvement (greater 

than 1 deciview) at all eleven Class I areas impacted by NGS. 

 Timeframe and Credit for Prior Reductions:

EPA is exercising our discretion under the Tribal Authority Rule (TAR) to allow 

additional time for NGS to reduce emissions and to give credit for prior reductions. 

Sources located on tribal land are not subject to the same legal deadlines as sources 

on state land. The credit for the prior NOx reductions, achieved over 2009-2011, is a 

key component of EPA’s proposed framework for Alternatives to BART.

General Background

 NGS is located on the Navajo Nation Indian Reservation near Page, Arizona and is 

one of the largest sources of NOx in the country. NGS is a 2,250 MW coal-fired 

power plant.

 NOx not only impairs visibility by increasing haze, but also emits pollutants that 

affect public health. EPA’s proposed action gives NGS several options that will all 

substantially improve air quality and visibility. 

 Under the Clean Air Act, Congress required that EPA improve visibility in 156 

federal national parks and wilderness areas across the country. States are required to 

adopt Regional Haze plans that improve visibility over time. These plans include 

BART determinations, where older sources are evaluated for additional pollution 

controls. Most states have completed this process and many have required stationary

sources under their jurisdiction to install new air pollution controls for BART. The 

Navajo Nation has not developed a Tribal Implementation Plan for BART. Therefore, 

EPA is developing a Federal Implementation Plan for Navajo Generating Station.

 NGS has already installed pollution control equipment to significantly reduce 

emissions of sulfur dioxide (SO2) and particulate matter in order to protect visibility 

and improve air quality. Now EPA is proposing that the facility take comparable 

action to reduce NOx emissions, the last component of pollution that significantly 

affects regional haze. 
 In 2011 alone, 4 million people visited the Grand Canyon. Visibility is important to 

healthy tourism and the economic vitality of the states, local and tribal communities 

in the West.

 NGS is co-owned by the U.S. Bureau of Reclamation (24.3%), Salt River Project 

(21.7%), Los Angeles DWP (21.2%), Arizona Public Service (14%), Nevada Power 

(11.3%) and Tucson Electric Power (7.5%). 

 Los Angeles DWP and Nevada Power have stated their intentions to pull out of NGS. 

Together they own 32.5 % of the plant, or almost a third of the facility, or almost one 

unit of the 3-unit facility.

Next Steps 

 EPA is extending the close of the public comment period to January 6, 2014.

 EPA will be holding five open house and public hearing events at locations 

throughout Arizona on November 12-15, 2013, as follows:

Date Time Location

November 12 

Tuesday Morning

10AM – 1PM

Concurrent Open House/Hearing

LeChee Chapter House, On Coppermine Road, 3 miles 

south of Page, in LeChee, Arizona

November 12 

Tuesday Evening

Open House: 3PM – 5PM

Public Hearing: 6PM – 9PM

Page High School Cultural Arts Building, 

434 Lake Powell Blvd., Page, Arizona

November 13 

Wednesday

Open House: 3PM – 5PM

Public Hearing: 6PM – 9PM

Hopi Day School, 

Quarter-mile East Main Street, Kykotsmovi, Arizona

November 14 

Thursday

Open House: 3PM – 5PM

Public Hearing: 6PM – 10PM

Phoenix Convention Center,

100 North 3rd Street, Phoenix, Arizona

November 15 

Friday

Open House: 3PM – 5PM

Public Hearing: 6PM – 9PM

Proscenium Theatre, Pima Community College West 

Campus, Center for the Arts Building, 2 miles west of 

I-10 on St. Mary’s Road, Tucson, Arizona

For more information, see: http://www.epa.gov/region9/air/navajo/