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BECKHAM, LISA

From: Lusk, Joel <joel_lusk@fws.gov>

Sent: Monday, June 23, 2014 8:02 AM

To: Rios, Gerardo; Lee, Anita

Cc: david_campbell@fws.gov; wally_murphy@fws.gov; mckauaghan.colleen@epa.gov;

gtom@nndfw.org; jcole@nndfw.org; edithsnyder@navajo-nsn.gov;

Richard.Grimes@aps.com; matt.wunder@state.nm.us; Harrilene Yazzie; Rick Williamson; 

Marcelo Calle; Alexander Smith; Silva, Sandra; Brenda Smith; Carrie Marr

Subject: Re: Request for concurrence on EPA determination that installation of new air pollution 

controls at Four Corners Power Plant is not likely to adversely affect listed species

Attachments: 2014-I-0338_USFWS Concurrence letter on EPA finding of MA,NLAA for Four Corners 

Power Plant Air Quality Permit.pdf

Mr. Gerardo C. Rios 

Chief, Permits Office

U.S. Environmental Protection Agency (Air-3)

75 Hawthorne Street

San Francisco, CA 94105

Dear Mr. Rios:

Thank you for the Biological Assessment (BA) provided on May 19, 2014, and email requesting consultation under section 7 of 

the Endangered Species Act of 1973, as amended (ESA; 16 U.S.C. § 1534 et seq.) for the proposed issuance of a U.S. 

Environmental Protection Agency (EPA) air quality permit allowing Four Corners Power Plant (FCPP), in San Juan County, New 

Mexico, to increase emissions of sulfuric acid mist (SAM). 

The U.S. Fish and Wildlife Service (Service) concurs with EPA’s determination that the proposed action “may affect, but is not 

likely to adversely affect” the federally listed, proposed species, or designated critical habitats described because the effects 

were considered discountable or insignificant. 

(See attached correspondence "2014-I-0338_USFWS Concurrence letter on EPA finding of MA,NLAA for Four Corners Power 

Plant Air Quality Permit")

Please contact the Service to verify the above determination and concurrence are still valid if: 1) future surveys detect listed, 

proposed, or candidate species in habitats where they have not been previously observed; 2) the project is changed or new 

information reveals effects of the action to the listed species or their habitats to an extent not considered in these evaluations; or 

3) a new species is listed that may be affected by this project.
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This concludes ESA section 7 consultation on the proposed issuance of a Federal PSD permit for SAM emissions by FCPP 

under the Clean Air Act. 

 ̧ ̧.· ́ ̄`·. ̧ ̧.><((((o>. ̧ ̧.· ́ ̄`·. ̧ ̧.>+++('>. ̧ ̧.· ́ ̄`·. ̧ ̧.><((((o>. ̧ ̧.· ́ ̄`·. ̧ ̧.>+++('>. ̧ ̧ 

Joel D. Lusk, Acting Chief, Aquatic Recovery Programs Branch 

US Fish and Wildlife Service, New Mexico Ecological Services 

2105 Osuna Road NE, Albuquerque, NM 87113-1001 

T: 505-761-4709 F: 505-346-2542 Email: joel_lusk@fws.gov

 ̧ ̧.· ́ ̄`·. ̧ ̧.><((((o>. ̧ ̧.· ́ ̄`·. ̧ ̧.>+++('>. ̧ ̧.· ́ ̄`·. ̧ ̧.><((((o>. ̧ ̧.· ́ ̄`·. ̧ ̧.>+++('>. ̧ ̧ 

On Mon, May 19, 2014 at 12:55 PM, Rios, Gerardo <Rios.Gerardo@epa.gov> wrote: 

 

Dear Mr. Campbell and Mr. Lusk: 

 

EPA is requesting concurrence under Section 7 of the Endangered Species Act (ESA) with our finding that an 

increase in emissions of sulfuric acid mist (SAM) from the Four Corners Power Plant (FCPP), located on the 

Navajo Nation, near Farmington, New Mexico, is not likely to adversely affect listed species. 

 

Arizona Public Service Company (APS), the operator and co-owner of FCPP, has submitted an application to 

EPA for a federal permit allowing it to increase emissions of sulfuric acid mist (SAM) as a result of their plan 

to install selective catalytic reduction (SCR) on Units 4 and 5 at FCPP (Project). The installation of SCR will 

significantly reduce emissions of oxides of nitrogen (NOx) from FCPP. NOx is a criteria air pollutant that 

affects human health and visibility, and contributes to ozone formation and acid deposition. The Federal 

Action under consideration for this consultation is a Federal Prevention of Significant Deterioration (PSD) 

permit for SAM under the Clean Air Act. 

 

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.

 

On August 24, 2012, EPA promulgated a Federal Implementation Plan (FIP) that requires FCPP to reduce 

emissions of NOx by 80 to 87 percent under the Best Available Retrofit Technology (BART) requirement of 

the Clean Air Act and the Regional Haze Rule. The FIP requires APS to implement one of two options to 

reduce emissions of NOx: (1) install SCR on Units 1-5 by October 2017 (BART), or (2) close Units 1-3 by 

January 1, 2014 and install SCR on Units 4 and 5 by July 31, 2018 (BART Alternative). To comply with the 
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FIP, APS has elected to implement the BART Alternative, and accordingly, APS permanently retired Units 1-3 

at FCPP by January 1, 2014, resulting in substantial emission reductions of numerous air pollutants from 

FCPP, including NOx, mercury, selenium, and sulfur dioxide (SO2). The operation of SCR on Units 4 and 5 

will result in an increase in emissions of SAM; therefore, APS must apply for a permit under the PSD program 

and install Best Available Control Technology (BACT) to control emissions of SAM. Because Units 4 and 5 

are already equipped with wet scrubbers and baghouses, when EPA proposes a PSD permit for public review, 

EPA’s BACT determination will set an emission limit for SAM that will likely require sorbent injection to 

increase the capture and control of SAM in the baghouses. 

 

At our request, APS submitted a draft Biological Assessment (BA), developed by AECOM, to examine 

potential impacts from our issuance of the PSD permit to listed species and critical habitat (attached).The BA 

identified seven species and their critical habitat that are listed or proposed to be listed as federally endangered 

or threatened that have the potential to occur within the Action Area of the facility. The Action Area includes 

areas where potential direct and indirect impacts on listed species and critical habitat may occur. The BA refers 

to the Action Area as the Deposition Area, and is the area where the predicted increase in soil concentration of 

metals (as a proxy for deposition of acids and other particulate matter) after 25 years of future full load 

operation of Units 4 and 5 with SCR, was modeled to be more than one percent of the current concentrations. 

The species that may occur within this area are the Mexican spotted owl (threatened), the Southwestern willow 

flycatcher (endangered), the yellow-billed cuckoo (proposed for listing as threatened), the Colorado 

pikeminnow (endangered), the razorback sucker (endangered), the Mancos milk-vetch (endangered), and the 

Mesa Verde cactus (threatened). 

 

Installation and operation of the SCR, including associated buildings, such as storage silos, will occur within 

the existing fenceline of FCPP, in the middle of disturbed areas or within existing buildings. Although delivery 

of the reagents necessary for the operation of SCR (and any additional controls that EPA requires as BACT for 

SAM) will increase truck traffic to FCPP, the deliveries will occur on existing roads and paved areas within the 

existing fenceline of the facility. Analysis in the BA indicates that listed species and critical habitat do not 

occur within the fenceline of FCPP. 

 

The BA evaluates the effect of acid deposition to soils and surface water to determine whether the installation 

and operation of SCR would decrease the pH of soils and surface water to make existing metals more 

biologically available. Based on the analysis, the BA concludes that deposition of acid gases from FCPP would 

not significantly alter the pH of soil or surface water in the Deposition Area. The BA also considered direct 

deposition of acid mist, and pollutants that contribute to acid deposition (SO2 and NOx), on vegetation in 

general. The BA cites to a study by the World Health Organization (WHO) that concludes deposition of SAM 

tends to be greater on forested areas and vegetation at higher altitudes, and estimates critical load guidelines for 

SO2 and NOx to be 250 sulfur equivalents per hectare per year, and 5 kilograms of nitrogen per hectare per 

year. The modeling analysis in the BA predicts a maximum annual average of 29.9 sulfur equivalents per 

hectare per year and 0.037 kilograms of nitrogen per hectare per year in the Deposition Area. 

 

Based on documents from the US FWS, including recovery plans, goals, and listing documents, the primary 

threats to all of the eight species that may occur within the Deposition Area relate to extensive habitat loss or 

modification resulting from anthropogenic activities. Establishment of non-native invasive species and 
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competition and predation were also identified as threats to the Southwestern willow flycatcher, the yellowbilled cuckoo, the Colorado pikeminnow, the razorback sucker, and the roundtail chub. Although pollutants 

associated with coal combustion, e.g., mercury and selenium, are listed as potential threats to the fish species, 

the closure of Units 1-3 at FCPP have reduced overall emissions of all pollutants, including mercury and 

selenium, and acid deposition (associated with the increase in SAM from the installation of SCR on Units 4 

and 5) has not been identified as a potential threat to fish species. However, in the 1989 Final Recovery Plan 

for the Mancos milk-vetch (1989 Recovery Plan), acid deposition from power plants was identified as a 

potential threat. The 1989 Recovery Plan stated “Presently, there are no data to suggest that acidic wet or dry 

deposition pose any threat to the Mancos milkvetch, though no data have been collected. However, 

northwestern New Mexico is a center for power production in the region. Two power plants are already on 

line, and another is scheduled for construction. Particulate and chemical fallout from power plants is often 

acidic, and thus acidic deposition is a potential threat to the species.” More recent information from the US 

FWS, i.e., the 2011 five-year review of the Mancos milk-vetch (2011 five-year review), does not provide 

further discussion of, or any data related to, the potential threat of acid deposition to the species. On May 9, 

2014, EPA conducted a literature search on the effects of acid deposition on milk-vetch (i.e., search terms 

Mancos milk vetch, Mancos milk-vetch, Astragalus humullimus, or milk vetch; and acid deposition, acid 

uptake, or acid rain, or sulfuric acid) on the Science Direct “Web of Science” database and Google Scholar. 

The only relevant documents from the search were the 1989 Recovery Plan, the 2011 five-year review, and the 

April 2007 Biological Assessment for the Desert Rock Energy Project (DREP), prepared by Ecosphere 

Environmental Services for the Bureau of Indian Affairs and the US FWS, with general references to the 

potential for acid rain to affect vegetation. We note that the draft Biological Opinion for DREP, prepared by 

the US FWS, did not focus on or address potential impacts of acid gases on the Mancos milk-vetch. 

 

The installation of SCR on Units 4 and 5 at FCPP to reduce emissions of NOx by 18,600 tons per year will 

result in a projected increase in emissions of SAM of 230 tons per year. The primary threats to the listed or 

proposed species relate to habitat destruction or modification, and the installation and operation of SCR will 

occur within the existing fenceline and disturbed areas of FCPP. The increase in SAM emissions is not 

expected to alter the pH of soils or surface water in the Deposition Area, and acid deposition rates of sulfur and 

nitrogen are expected to be well below critical load guidelines put forth by the WHO. Although acid 

deposition was previously identified as a potential threat to the Mancos milk-vetch, there is no data to suggest 

that acid deposition poses an actual threat to the species. Therefore, we find that if EPA issues a PSD permit to 

FCPP to install and operate SCR on Units 4 and 5, the increase in emissions of SAM is not likely to adversely 

affect federally-listed species or their critical habitats, in accordance with 50 CFR 402.13 and 402.14(b). EPA 

requests concurrence from the Service with this finding. 

 

Thank you in advance for your attention to this request. If you have any questions, please contact Anita Lee at 

(415) 972-3958 or lee.anita@epa.gov. 

 

Gerardo C. Rios 

Chief, Permits Office 

(415) 972-3974 

 
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