SRP submitted an ESA Analysis for a Low-NOx Burner Project to EPA in April 2008 

(revised July 2008). Based on the habitat conditions surrounding the Low-NOx Burner project 

area, only one species from the Federal Coconino County threatened and endangered species list 

was expected to occur in the Project vicinity: the California Condor (Gymnogyps californianus). 

No breeding or nesting sites were observed for this species in the Low-NOx Burner Project area. 

The Low-NOx Burner Project occurred 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 

increases of CO 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. However, the modeling analysis showed that impacts of 

CO from the Low-NOx burner project exceed the Significant Impact Limits (“SILs”) at least 8 

kilometers from the facility boundary. EPA reviewed the analysis submitted by SRP and found 

that the Low-NOx burner 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). FWS

replied in concurrence with this finding on November 13, 2008.

Since 2008, two additional species have been added to the Federal Coconino County 

threatened and endangered species list: the Northern Mexican Garter Snake (Thamnophis eques 

megalops) and the Narrow-headed Garter Snake (Thamnophis rufipunctatus). Both of these 

species are strongly dependent on aquatic and riparian habitats. Several species included in the 

species list for the 2008 Low-NOx Burner Project, including the Razorback sucker (Xyrauchen 

texanus) and the Yellow-billed Cuckoo (Coccyzus americanus), are known to occupy areas with 

similar habitats to the Northern Mexican Garter Snake and Narrow-headed Garter Snake. As 

with other species dependent on the presence of aquatic or riparian habitat, both the Northern 

Mexican Garter Snake and Narrow-headed Garter Snake are unlikely to be found within the 

vicinity of the RCTS Project area because of the lack of suitable habitat. Conference with the 

FWS has confirmed that these species are not likely to be found near the NGS. The California 

Condor remains the only species listed on the Federal Coconino County threatened and 

endangered species list which is expected to occur in the vicinity of the RCTS Project area at the 

NGS.

SRP conducted a PM10 and PM2.5 modeling analysis for the RCTS Project to determine 

the impact of emissions increases on the annual and 24-hour PM10 and PM2.5 National Ambient 

Air Quality Standards (“NAAQS”). The modeling showed that maximum concentrations of PM10

and PM2.5 occur at the facility boundary and that increases of these pollutants of do not exceed 

the SILs outside the existing facility boundary and do not result in ambient concentrations that 

exceed any applicable NAAQS. Therefore, SRP determined that a more detailed review would 

not be required to analyze the impacts of PM10 and PM2.5 on plants, soils and animals. EPA has 

reviewed the application and modeling report for the RCTS Project and has concluded that the 

increase in emissions will not affect the California Condor because emissions from the Project 

extending beyond the existing facility boundary are insignificant.

On November 20, 2015, EPA sought concurrence from the FWS in the form of a letter 

for its finding that the RCTS Project may affect, but is not likely to adversely affect, any 
federally-listed endangered or threatened species or designated critical habitat for such species.

Subsequent discussion with the FWS indicated that they believe that no endangered or threatened 

species or critical habitat will be affected by the RCTS Project, nor is it likely to jeopardize the 

continued existence of any proposed species or adversely modify any proposed critical habitat. 

FWS followed by stating in a letter to EPA dated December 18, 2015 that no further review is 

required for the RCTS Project. Therefore, it is EPA’s determination that the Tribal NSR minor 

modification will have no effect on endangered or threatened species in the area, and further 

action with the FWS is not necessary in accordance with 50 CFR 402.13.