UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

REGION IX 

75 Hawthorne Street 

San Francisco, CA 94105·3901 

November 10, 2008 

Steven Spangle 

Field Supervisor 

U.S. Fish and Wildlife Service 

2321 West Royal Palm Road 

Suite 103 

Phoenix, Arizona 85021 

Re: Request for Concurrence with EPA Finding of May Effect I No Likely Adverse Effect 

under Section 7 of the ESA for the Navajo Generating Station Low-No; Burner Project 

Dear Mr. Spangle: 

By this letter, the U.S. Environmental Protection Agency, Region IX ("EPA") seeks 

concurrence from the U.S. Fish and Wildlife Service ("Service") under Section 7(a)(2) of the 

Endangered Species Act ("ESA") with our finding that emissions increases of carbon monoxide 

("CO") from the Navajo Generating Station ("NGS") Low-Nf), Burner Project ("Project") may 

affect, but is not likely to adversely affect, the continued existence of any endangered or 

threatened species or result in the destruction or adverse modification of such species' designated 

critical habitat. NGS has applied to EPA for a Federal Prevention of Significant Deterioration 

("PSD") permit as required by Part C of the Clean Air Act and regulations at 40 C.F.R. § 52.21. 

Background information on the PSD program and more detailed information regarding the 

Project are included below. 

EPA is responsible for complying with ESA Section 7 requirements with respect to 

Federal PSD permitting and is the lead Federal Agency for Section 7(a)(2) compliance for this 

Project. Because the Project has the potential to affect listed species and/or critical habitat, final 

action on this PSD permit must not occur until EPA has determined that permit issuance will be 

consistent with the substantive and procedural requirements of the ESA. 

NGS is located on the Navajo Nation Indian Reservation, approximately five miles east 

of Page, in Coconino County, Arizona. The facility consists ofthree existing coal-fired steam 

generating units, with a combined power generation capacity of 2,250 net megawatts. The three 

units are operated by Salt River Project Agricultural and Power District ("SRP") and co-owned 

by the following six entities: U.S. Bureau of Reclamation, SRP, Los Angeles Department of 

Water and Power, Arizona Public Service Company, Nevada Power, and Tucson Electric Power 

Company. 

SRP has proposed the current Project as a voluntary measure to significantly reduce 

emissions of oxides of nitrogen (NOx) from all three boiler units at the NGS. The project 

Printed on Recycled Paper 
involves the installation of Low-NO, Burners (LNB) with Separated Over-fire Air (SOFA) 

systems over a three-year period. LNB and SOFA systems reduce NOx emissions by controlling 

air and fuel flow to create fuel-rich and oxygen-poor conditions in the burner, and stage the 

addition of over-fire air beyond the burner combustion zone to complete combustion at a lower 

temperature which reduces the formation ofthermal NOx. Reductions in NOx achieved through 

staged combustion result in simultaneous increases in CO, a by-product of incomplete 

combustion. 

After the LNB and SOFA systems are installed on all three units at NGS , SRP estimated 

NOx emissions to decrease by over 20,000 tons per year ("tpy"). SRP has determined that the net 

emission increase of CO resulting from the proposed Project will exceed the 100 tpy PSD 

significance threshold for CO, triggering Federal permitting requirements. Emissions of all other 

air pollutants are expected to remain unchanged as a result of this Project and thus are not subject 

to PSD review. 

SRP submitted an ESA Analysis for this Project to EPA in April 2008 (revised July 

2008). Based on the habitat conditions surrounding the project area, only one species from the 

Federal Coconino County threatened and endangered species list would be expected to occur in 

the Project vicinity: the California condor (Gymnogyps californianusi. No breeding or nesting 

sites have been observed for this species in the Project area. The Project will occur within the 

boundaries of the active plant site, which is already a developed industrial area, and it is expected 

that the one species identified in the analysis generally avoids human contact and thus avoids the 

facility area. In addition to the possible construction impacts on the listed species, SRP 

conducted a CO modeling analysis to determine the impact of CO emissions increases on the 1­

hour and 8-hour average National Ambient Air Quality Standards ("NAAQS"). The modeling 

results showed that emissions increase s ofCO from the Project do not result in ambient 

concentrations that exceed the NAAQS , therefore, SRP concluded that a more detailed review 

would not be required for CO impacts on plants, soils, and animals. 

EPA reviewed the analysis submitted by SRP and finds that the Project may affect, but is 

not likely to adversely affect the California condor or its critical habitat, in accordance with 50 

C.F.R. §§ 402.13 and 402.14(b). I am writing to request written concurrence from the Service 

with this finding. 

If you have any questions regarding this Project, please contact me at (415) 972-3974 or 

Leslie Ramirez, of my staff, at (415) 972-3978. 

?t/IL

Gerardo C. Rios 

Chief, Air Permits Office 

cc:	 John Nystedt, USFWS (via electronic mail) 

Brenda Smith, USFWS (via electronic mail)