Region 9

Overview of EPA Propos

Rulemaking for

Navajo Generating Stati

Plan to Reduce Emissions of Oxides 

Nitrogen to Improve Visibility at Federa

Protected National Parks Affected by N
Region 9
Region 9

Overview

• On February 5, EPA published our propo

BART determination and an alternative to for NGS

• We proposed two things: 

– an emission limit for oxides of nitrogen (NOx) 

achievable with installation of selective catalyreduction (SCR) in 5 years (BART) and 

– a framework to give NGS credit for early NOx

reductions and provide NGS with more flexibthe timing of compliance (alternative to BART
Region 9

History of NGS

• NGS is located on Navajo Nation and burns co

is mined on reservation lands of the Navajo Naand Hopi Tribe

• U.S. Bureau of Reclamation owns 24.3% of N

the benefit of the Central Arizona Project

• NGS plays important roles in Arizona:

– Employment – Source of revenue to Navajo Nation and Hopi T– Source of electricity – Electricity is also used to pump CAP water and 

terms of several water settlement agreements wtribes located in Arizona 
Region 9

Why Are We Evaluating NG

• Congress required EPA to improve visibility a

National Parks and Wilderness Areas (Class – Regional Haze Program

• Large, old sources of air pollution that affect 

in Class I areas must be evaluated to determnew air pollution controls should be required Available Retrofit Technology – BART)

• NGS affects visibility at 11 Class I areas, incl

Grand Canyon and Canyonlands and is subjBART requirement of the Regional Haze Pro
Region 9

• Air pollutants (for example, gases like NO

form particulate matter) cause regional ha

• By reducing emissions of air pollutants tha

haze, we can improve visibility 

• The same pollutants that impair visibility a

concern for human health, therefore reduchaze also improves air quality

• EPA or State Agencies evaluate whether 

controls should be required for all facilities are subject to BART requirement

How do we improve visibili
Region 9

• BART is determined based on a 5-factor a

– Factor 1 – How much would controls cost the f– Factor 2 – Are there energy, economic, or othe

environmental impacts of the control?

– Factor 3 – What are the existing controls at the – Factor 4 – What is the remaining useful life of 

facility?

– Factor 5 – How will visibility improve by adding 

controls?

How is BART determined
Region 9

Brief Overview of 5-Factor Analys
Region 9

• Based on our 5-factor analysis, EPA dete

that installation of SCR + LNB/SOFA at Nreduce NOx emissions:

– is cost-effective – would not create a competitive disadvantage – would result in a perceptible improvement in v

the Class I areas affected by NGS

Why Did We Propose New Cont
Region 9

• Given the importance of NGS to tribes located in 

and its location on tribal land, it is appropriate to padditional flexibility to the owners

• Compliance timeframes for alternatives to BART 

Regional Haze Rule that apply on state land do non tribal land

• Under the Tribal Authority Rule, EPA has discreti

determine if and when a FIP is necessary and apincluding the timeline for complying with those requirements

Why is EPA Proposing an Alterna
Region 9

• The Regional Haze Rule (RHR) requires either BART 

alternative measure that will achieve greater reasonaprogress than BART (more emission reductions)

• EPA is proposing to give NGS credit for early and vol

reductions in order to extend the compliance date to 2meeting BART limits

• This alternative achieves greater reasonable progress 

BART

• EPA included a framework for stakeholders to conside

beyond 2023 by implementing additional emission redthat would ensure greater reasonable progress than B

Framework for Considering Altern
Region 9

• EPA will hold public hearings at least 30 days prior t

of the comment period

• In your comments, please provide supplemental info

and documentation to support your comment

• EPA has received several requests to extend the pu

comment period by an additional 90 days, which we 

• EPA anticipates stakeholders will suggest other alte

BART that ensure additional emission reductions in for more time to comply with the BART limits

• EPA may put forth a supplemental proposal if sugge

alternatives achieve greater reasonable progress tha

What Happens Next?
Region 9

• EPA will review and consider all comments 

making a final decision

• We will respond to all comments in writing a

incorporate any changes to the proposal as of comments in our final decision

• Documents will also be posted online and in 

docket for this rulemaking

What Happens After the Comment 
Region 9

For Further Information

Name Role Phone Em

Colleen 

McKaughan

Associate Director, 

Air Division

520.498.0118 McKaughan.Co

Ann Lyons Office of Regional 

Counsel

415.972.3883 Lyons.Ann

Anita Lee Staff Lead, Air 

Division

415.972.3958 Lee.Anita