Prepared for: Prepared by: Arizona Public Service AECOM Phoenix, AZ Fort Collins, CO May 2014 

### Environment



# Biological Assessment for the Four Corners Power Plant SCR Retrofit ProjectB iological A ssessment for the Four Corners Power Plant SCR Retrofit Project

AA

- 1 

## List of Acronyms and Abbreviations

ANC acid neutralizing capacity APS Arizona Public Service Company BA Biological Assessment BART Best Available Retrofit Technology BISON

- M Biota Information System of New Mexico BLM Bureau of Land Management

cm centimeter

cm 3 cubic centimeter DPS distinct population segment DSI dry sorbent injection EIS Environmental Impact Statement EPA U.S. Environmental Protection Agency EPRI Electric Pow er Research Institute ESA Endangered Species Act FCPP Four Corners Power Plant FIP Federal Implementation Plan FLAG Federal Land Manager’s Air Quality Related Values Work Group FR Federal Register ft feet g gram H+ hydronium ion H 2 SO 4 sulfuric acid ha hec tare HCl hydrogen chloride HF hudrogen fluoride in inch IPaC Information, Planning, and Conservation (USFWS) km kilometer L liter

m meter

m 2 square meter

mm millimeter ml milliliter MW megawatt N nitrogen NAAQS National Ambient Air Quality Standard NEPA National Environmental Policy Act NHNM Natural Heritage New Mexico NNNHP Navajo Nation Natural Heritage Program NO X nitrogen oxide NRCS Natural Resources Conservation Service PM particulate matter PM 10 particulate matter with an aerodynamic diameter of 10 microns or less PM 2.5 particulate matter with an aerodynamic diameter of 2.5 microns or less PSD Prevention of Significant Deterioration S sulfur SCR Selective Catalytic Reduction SO 2 sulfur dioxide SO 3 sulfite SWReGAP South West Regional Gap Analy sis ProjectB iological A ssessment for the Four Corners Power Plant SCR Retrofit Project

AA

- 2 t/Kt tons/kiloton tpy tons per year U.S. United States USC United States Code USFWS U.S. Fish and Wildlife Service USGS U.S. Geological Survey WHO World Health Organization YOY young

- of

- the

- year yr ye ar 0.1N 10 percent Normal 95UCL 95 percent upper confidence limitBiologica l Assessment for the Four Corners Power Plant SCR Retrofit Project

i 

## Contents

1.0 Project Background

................................ ................................ ................................ ............ 1

2.0 Proposed Action

................................ ................................ ................................ ................. 2

2.1 Action Area

................................ ................................ ................................ .............................. 4

2.2 Species Considered in the Analys is

................................ ................................ ....................... 6

2.3 Acid Deposition from SCR Operations

................................ ................................ ................... 8

2.4 Particulate Matter

................................ ................................ ................................ .................... 8



### 3.0 Species Accounts and Environmental Baseline Conditions

................................ ....... 10

3.1 Birds

................................ ................................ ................................ ................................ ....... 10
3.1.1 Natural History and Habitat Association

................................ ................................ 10
3.1.2 Potential Presence in the Deposition Area

................................ ........................... 13

3.2 Fish

................................ ................................ ................................ ................................ ........ 13
3.2.1 Natural History and Habitat Association

................................ ................................ 13
3.2.2 Potential Presence in the Deposition Area

................................ ........................... 15

3.3 Plants

................................ ................................ ................................ ................................ ..... 15
3.3.1 Natural History and Habitat Association

................................ ................................ 15
3.3.2 Potential Presence in the Deposition Area

................................ ........................... 17



### 4.0 Effects of the Proposed Action

................................ ................................ ....................... 20

4.1 SCR Installation

................................ ................................ ................................ .................... 20

4.2 Acid Deposition on Soils

................................ ................................ ................................ ....... 20

4.3 Acid Deposition in Surface Water

................................ ................................ ......................... 21

4.4 Particulate Matter

................................ ................................ ................................ .................. 21

4.5 Plants

................................ ................................ ................................ ................................ ..... 22
4.5.1 Impact Evaluation

................................ ................................ ................................ ... 22
4.5.2 Determination

................................ ................................ ................................ ......... 23

4.6 Birds and Fish

................................ ................................ ................................ ....................... 23
4.6.1 Impact Evaluation

................................ ................................ ................................ ... 23
4.6.2 Determination

................................ ................................ ................................ ......... 23



### 5.0 Cumulative Effects

................................ ................................ ................................ ............ 25

6.0 References

................................ ................................ ................................ ......................... 27Biologica l Assessment for the Four Corners Power Plant SCR Retrofit Project

ii 

## List of Tables

Table 2

- 1 Threatened, Endangered, Proposed and Candidate Species Con sidered in this Analysis

................................ ................................ ................................ ....................... 6

Table 2

- 2 Modeled Annual Acid Deposition from FCPP in Top 2 cm of Soil from Operation of Units 4 and 5 with SCR installed

................................ ................................ ..... 9



## List of Figures

Figure 2

- 1 Location of Proposed Construction at FCPP

................................ ................................ ........ 3
Figure 2

- 2 Deposition Area Boundaries

................................ ................................ ................................ . 5
Figure 3

- 1 Potential Habitat for Mancos Milk

- vetch in Deposition Area

................................ .............. 18
Figure 3

- 2 Potential Habitat for Mesa Verde Cactus in Deposition Area

................................ ............ 19Biological Assessment for the Four Corners Power Plant SCR Retrofit Project

1 

## 1.0 Project Background

Arizona Public Service Company (APS) operates the Four Corners Power Plant (FCPP), a privately owned and operated coal

- fired power plant located on the Navajo Nation, about 25 miles west of Farmington, New Mexico

. Th e facility currently consists of two power generating units, Units 4 and 5, with a total capacity of approximately 1,500 megawatts (MW).

On August 24, 2012, the United States Environmental Protection Agency ( EPA ) promulgated a source

specific Federal Implementation Plan ( FIP ) requiring the FCPP to achieve emissions reductions required by the Clean Air Act's Best Available Retrofit Technology (BART) provision (77 F ederal Register [F R ] 51620). At the time the FIP was issued, APS operated five units with a total capacity of 2,100 MW

. The FIP established two, alternative compliance options. APS could retrofit all five units at FCPP to meet certain emission limits (Option 1) or, under an alternative plan proposed by APS, it could install Selective Catalytic Reduction (SCR) controls on Units 4 and 5 in 2018 and retire Units 1, 2 and 3 by January 1, 2014 (Option 2). APS selected Option 2 and retire d Units 1, 2, and 3 at the end of 2013. Units 4 and 5 will continue to operate , but a Selective Catalytic Reductio n (SCR) system on each unit is needed to reduce nitrogen oxides ( NO X ) emissions to the required limit in the FIP. Construction o f the SCR system s is expected to start in mid

- 2015 in order to meet a FIP

- imposed operations deadline of July, 2018. The FCPP SCR Retrofit Project will decrease NO X emissions from Units 4 and 5 by approximately 18,600 tons per year (tpy) , in addition to the emission reductions from shutdown of Units 1 through 3

. Beside s a reduction in NOx emissions, EPA is requiring Uni ts 4 and 5 to meet a specific particulate matter (PM) emission limit that will be achieved through operation of existing baghouses

.

A Prevention of Significant Deterioration ( PSD ) permit application was submitted to the EPA Region 9 in April 201 4 (AECOM 2014)

, to address potential emissions increases related to the installation of the SCR systems at FCPP. Because the FCPP is located in an attainment area, the project must be evaluated to determine whether the proposed major modification will result in a signific ant net emissions increase and be subject to PSD permitting requirements. A major modification is defined as a physical change or change in the method of operation at a major source that results in both a significant emissions increase and a significant ne t emissions increase of a regulated pollutant. A netting analysis that accounts for contemporaneous emission increases and decreases (such as the shutdown of Units 1 through 3) is required for emissions of these pollutants. In accordance with PSD rules, t he contemporaneous period begins 5 years prior to the start of construction and ends when the project begins operating. Because the installation of SCR systems on coal

- fired power plants leads to potential increases in emissions of sulfuric acid (H 2 SO 4 ) mi st, respirable particulate ( particulate matter with an aerodynamic diameter of 10 microns or less [PM 10 ]), and fine particulate matter (particulate matter with an aerodynamic diameter of 2.5 microns or less [PM 2.5 ]), a PSD applicability and a netting analy sis w ere performed. Because the shutdown of Units 1 through 3 will lead to significant decreases in the emissions of PM 10 and PM 2.5 from the FCPP, it was determined (as demonstrated in the PSD application) based upon an emissions netting analysis, that on ly emissions of H 2 SO 4 mist from Units 4 and 5 will be subject to PSD requirements

. While the PSD permitting process is not sub ject to the National Environmental Policy Act ( NEPA )

, EPA require s an analysis of potential impacts to federally listed species from the federal action ( i.e., PSD permit issuance) under the Endangered Species Act (ESA). In order t o evaluate the po tential impacts, the future emissions and deposition of acid

- generating compounds of sulfur and nitrogen were predicted using AERMOD , a steady

- state plume model that incorporates air dispersion

. This Biological Assessment (BA) evaluates the potent ial impacts to listed or proposed species or designated or proposed critical habitat under the ESA (16 United States Code [USC] § 1531 et seq. 1973) that may be caused by the installation and operation of SCR system s on Units 4 and 5.Biological Assessment for the Four Corners Power Plant SCR Retrofit Project

2 

## 2.0 Proposed Action

The FCPP SCR Retrofit Project involves the installation of emissions control technology at an existing coal

- fired power plant. In order to limit NO X emissions from Units 4 and 5, APS is planning to install SCR equipment on both units. The use of SCR tends to oxidize some s ulfur dioxide ( SO 2 ) to sulfites ( SO 3 ), which results in increased H 2 SO 4 mist, PM 10 , and PM 2.5 emissions. In order to mini mize H 2 SO 4 , PM 10 , and PM 2.5 emission increases, APS proposes to install a dry sorbent injection (DSI) system on each unit using hydrated lime as the sorbent.

A pneumatic dry sorbent truck unloading system and silo will be installed. Hydrated lime will be received by truck and pneumatically conveyed to a storage silo. The air emission sources associated with the use of lime will be truck travel on paved roads and a vent on the silo, which will have a baghouse for emissions control. The lime silo will be app roximately 14 f ee t in diameter and 80 f ee t tall , including lime transport equipment beneath the silo

. The SCR system s require the injection of ammonia as a reagent. The ammonia reagent for the SCR systems can be supplied by anhydrous ammonia, aqueous amm onia, or by conversion of urea to ammonia. APS has not yet selected the type of reagent, a decision that will be based on engineering designs when they are developed. A pneumatic urea pellet truck unloading system and silo may be installed if the urea reag ent option is selected for the SCR system s , or a n ammonia truck unloading station and storage tank will be installed if either the aqueous or anhydrous ammonia option is selected for the SCR system s

. Truck traffic will increase due to the delivery of reag ent and hydrated lime for the DSI system

. The amount of increased truck traffic will vary depending upon the reagent option selected

.

P roject construction will involve the use of heavy equipment for site preparation and installation of SCR on Units 4 and 5 and for construction of associated structures such as silos for storage of the sorbents and reagents and baghouses on the silos for control of PM 10 and PM 2.5 emissions

. New sources of air emissions consist of silos for storage of the sorbents and reagents and increase d road traffic for delivery of these sorbents and reagents , as well as a temporary increase in particulate matter and fugitive emissions from the use of construction equipment

. Figure 2

- 1 displays the locations of Units 4 and 5 and their stack s , the proposed silos, and the roads to be used by trucks to supply reagent and sorbent on the plant site

. Construction of the SCR system s is expected to start in mid

- 2015 or early 2016 with o peration planned by July 2018. All project

- related construction will be limited to industrial areas within the FCPP fenceline in the middle of paved, disturbed areas or within existing buildings that lack habitat for any federally listed species. Construction will be performed with heavy equipment such as earth

- movers, cranes, and trucks.

The areas that will be directly affected by construction are within an industrial part of the FCPP lease that is built

- up and lacks habitat for listed plants and wildlife. Therefore, this BA focuses on those portions of the action are a that contain habitat that could be affected by changes to emissions resulting from the Proposed Action

, delineated by determining where deposition of FCPP emissions is the highest.Biological Assessment for the Four Corners Power Plant SCR Retrofit Project

3 Figure 2

- 1 Location of Proposed New Sources at FCPPBiological Assessment for the Four Corners Power Plant SCR Retrofit Project

4 

### 2.1 Action Area

The action area is defined as all areas that may be affected by the federal action directly or indirectly. It is used to determine which species or critical habitat may be affected by delineating the geographic extent to evaluate. In the SCR process, sulfuric acid combines with ammonia to form particulates. For evaluating the potential effects of sulfuric acid and PM emissions from FCPP, the area of highest particulate deposition was used to represent the action area. The area of highest deposition for the FCPP SCR Retrofit Project is the same as the Deposition Area delineated for the Four Corners Power Plant and Navajo Mine Energy Project Environmental Impact Statement ( EIS ) based on air deposition

mo deling that considered the types of FCPP emissions, the prevailing winds, and the terrain. T he action area will be called the Deposition Area for the remainder of this BA.

To delineate the Deposition Area

, an initial screening process using p reliminary air deposition modeling was conducted using the CALPUFF model. A study by the Electric Power Research Institute ( EPRI 2011) indicated that the metals from coal

- fired power plants that typically contribute most to ecological risk include arsenic, cadmium, chro mium, and mercury. In addition, the ecological toxicity of antimony, lead, copper

, and selenium have been widely studied for their potential risk to humans and wildlife . Therefore, these eight metals were selected for modeling the deposition of particulate s to determine the extent of the Deposition Area because it is anticipated that the primary ecological risk driv ers are among these metals.

A screening procedure was applied to estimate potential changes to soil concentrations of the selected metals associ ated with 25 years of cumulative deposition from future continuous full load operations of all five units operating as they did until the closure of Units 1, 2, and 3. The purpose of this screening procedure was only to delineate boundaries of the area of highest deposition of emissions from the FCPP stacks (Deposition Area). It was not used to establish baseline conditions of metals in the environment.

The estimated amount of emitted metals in the air and the concentrations projected to be deposited as particulates on the soil surface were calculated based on modeling . These projections were compared to available measured soil concentrations of these metals within San Juan County, New Mexico , derived from the U.S. Geological Survey (US GS) PLUTO database for San Juan County, New Mexico (USGS 2012)

. This database , used to represent the current concentrations of soil metals, was developed through analyses of soil samples collected from San Juan County between 1965 and 1994 (during the peri od of operation of all five units at the FCPP) in support of USGS programs and was used to calculate the 95 percent upper confidence limit (95UCL) on the mean for each of the eight metals. The future deposition

- related surface soil concentration of each me tal calculated to accumulate over 25 years was computed (based on CALPUFF modeling) and compared to the corresponding 95UCL of the soil concentrations derived from the PLUTO data.

The Deposition Area, shown with the black and white dashed outline in Figure 2

- 2 , was determined by delineating the area where the predicted incremental increase in soil concentration of any of the metals after 25 years of future full load plant operations with SCR installed on Units 4 and 5 is projected to be more than one percen t of current concentrations (based on the PLUTO data). Although it was delineated based on metals deposition, the Deposition Area has been used to identify the area of the highest potential deposition of all particulates from the FCPP, including the sulfur ic acid and PM resulting from operation of the SCRs that are analyzed in this BA

. H 2 SO 4 forms either very small aerosol droplets or solid products resulting from chemical reactions in the air. “ Particulate ” is the term for particles found in the air includ ing solid products and liquid droplets

. B oth forms of particulates may be deposited on the ground through either wet deposition (precipitation) or dry deposition.Biological Assessment for the Four Corners Power Plant SCR Retrofit Project

5 Figure 2

- 2 Deposition Area BoundariesBiological Assessment for the Four Corners Power Plant SCR Retrofit Project

6 This approach is reasonable to calculate the effects of emissions resulting from the Proposed Action because H 2 SO 4 and PM are deposited as particulates in the same way that the modeled particulates are deposited. T he Deposition Area is the best representation of where the highest concentration of particulate matter and acidic compounds from future operations of FCPP Units 4 and 5 would be deposited based upon available information

. Beyond this area, the very small increase in deposition associated with FCPP fut ure emissions would be sufficiently low to be considered discountable 1 . The Deposition Area, including a portion of the San Juan River, represents the action area that was used to identify federally listed or proposed species and their habitats and any pot ential impacts from acid and PM deposition that may result from future FCPP operations with SCR

.



### 2.2 Species Considered in the Analysis
In order to address potential impacts to federally listed , proposed and candidate species, per direction from the U

. S

. F ish and W ildlife S ervice (USFWS) , the USFWS Information, Planning, and Conservation ( IPaC ) system and New Mexico Field Office county list for San Juan County, New Mexico

, were reviewed

. Based on this review, the potential for occurrence of listed, propose d

, and candidate species in the Deposition Area is summarized in Table 2

- 1

. The Deposition Area does not extend beyond San Juan County, New Mexico. Of these 12 species identified as potentially occurring in San Juan County, 8 were identified as potentially occurring within the Deposition Area based on :

1. I nformation from the USFWS, Navajo Nation Natural Heritage Program (NNNHP), and Natural Heritage New Mexico (NHNM);

2. H abitat requirements and the known distribution of these species from review of literatur e ( Biota Information System of New Mexico [ BISON

- M ] 2012; Mikesic and Roth 2008; USFWS 2012, 2011a,b, 2002a,b, 1985, 1984) ; and

3. M apping and analysis developed for the Habitat Model and Biological Survey Results for the Four Corners Power Plant and Associat ed Transmission Lines (referred to as the “ Habitat Model ” [AECOM 2013 a ])

.

Table 2

- 1 Threatened, Endangered, Proposed and Candidate Species Considered in this Analysis

Group Name ESA Status Potential Occurren ce within Deposition Area

Birds Southwestern willow flycatcher ( Empidonax traillii extimus ) Endangered Known to occur. Habitat found in cottonwood/willow and tamarisk vegetation communities along rivers and streams.

Birds Mexican spotted owl ( Strix occidentalis lucida ) Threatened May occur in the limited acreage of canyons and dense forests. Habitat includes mixed

- conifer forest, pine

- oak forest, and riparian areas

1 Using a percentage of background as a threshold for deposited metals is consistent with the acidic deposition

screening approach established by th e Federal Land Manager’s Air Quality Related Values Work Group (FLAG 2011). Given that the FLAG Deposition Analysis Threshold is based on 2 percent of natural background rather than measured background, a 1 percent threshold of measured soil concentration was determined to be a conservative screening threshold. Any soil concentration with an accumulation of less than 1 percent of background under future conditions (25 years of accumulation) was determined to be discountable.Biological Assessment for the Four Corners Power Plant SCR Retrofit Project

7 Table 2

- 1 Threatened, Endangered, Proposed and Candidate Species Considered in this Analysis

Group Name ESA Status Potential Occurren ce within Deposition Area

Birds Whooping Crane ( Grus Ame ricana ) Experimental Population Does not occur. Whooping cranes within New Mexico were included in the reintroduced Rocky Mountain population. In 1997, the remnant Rocky Mountain whooping crane population was designated experimental nonessential and the l ast remaining wild bird died in the spring 2002.

Birds Yellow

- billed cuckoo ( Coccyzus americanus ) Proposed May occur. Habitat may exist along the San Juan River in relatively dense, wooded, streamside riparian habitat.

Mammals Black

- footed ferret ( Muste la nigripes ) Endangered Does not occur although habitat (prairie dog colonies) exists. Considered extirpated in New Mexico with the last confirmed occurrence documented in 1934 (BISON

- M 2012).

Mammals Canada lynx ( Lynx canadensis ) Candidate Does not occur . Habitat does not occur in Deposition Area.

Fishes Colorado pikeminnow ( Ptychocheilus lucius ) Endangered; Designated critical habitat May occur. The San Juan River within the Deposition Area is part of the designated critical habitat.

Fishes Razorback s ucker ( Xyrauchen texanus ) Endangered; Designated critical habitat May occur. The San Juan River within the Deposition Area is part of the designated critical habitat.

Fishes Roundtail chub ( Gila robusta ) Candidate May occur. While there may be habitat, th is species has not been reported in the Deposition Area. There is a record of occurrence to the west in the San Juan River.

Plants Mancos milk

- vetch ( Astragalus humillimus ) Endangered May occur. Relatively small amount of habitat ( approximately 750 acres) in Deposition Area.

Plants Knowlton's cactus ( Pediocactus knowltonii ) Endangered Does not occur. Deposition Area is outside the known range of this species. The only viable population exists south of La Boca, Colorado, in San Juan County, New Mexico (US FWS 1985).

Plants Mesa Verde cactus ( Sclerocactus mesae

verdae ) Threatened May occur. Not reported south of the San Juan River. However, suitable habitat is found within the Deposition Area.Biological Assessment for the Four Corners Power Plant SCR Retrofit Project

8 

### 2.3 Acid Deposition from SCR Operations

The installation of SCRs a t FCPP will greatly decrease NO X emissions from Units 4 and 5 (approximately 18,600 tpy reduction) and slightly increase particulate matter and sulfuric acid mist emissions compared to current operating conditions associated with the two un its . Because the Deposition Area extends less than 50 kilometers ( km ) from the FCPP at its furthest distance, more detailed air dispersion and deposition modeling needed to predict the effects of stack emissions from future FCPP operations was performed us ing AERMOD (version 12345). This modeling calculated the annual quantities of acid

forming compounds emitted and deposited from operation of FCPP Units 4 and 5 with SCR systems. In order to use a single value to represent the acid

- forming compounds deposit ed from FCPP emissions, the results were converted to combined total hydronium ions. A single value to represent the concentration of acidic compounds is necessary to enable comparison between the quantity from FCPP future operations deposited on the groun d and the capacity of the environment to respond to this acid deposition, discussed in Section 4.0.

Hydrochloric acid and hydrogen fluorine emission factors were based on emission factors for coal

- fired electric generating units prepared by EPRI (2009). S ulfuric acid emission factors were provided by APS based on engineering estimates. Table 2

- 2 presents the findings of the deposition modeling for all acid

forming compounds emitted from FCPP stacks under the future operations of Units 4 and 5 with SCR as d escribed under the Proposed Action

. T his modeling did not account for the substantial reductions in emissions due to the shutdown of Units 1 through 3.



### 2.4 Particulate Matter
The National Ambient Air Quality Standards (NAAQS) were developed to establis h a limit on pollutants considered harmful to public health and the environment. The primary standards provide public health protection and the secondary standards provide for protection against decreased visibility and damage to animals, crops, vegetation , and buildings. According to air modeling performed in support of this PSD permit application (AECOM 2013 b ), although an increase in PM 10 and PM 2.5 emissions is projected due to increased sulfuric acid mist, the future operations of Units 4 and 5 with SCR will be well below both the primary and secondary NAAQS for PM 10 and PM 2.5 .Biological Assessment for the Four Corners Power Plant SCR Retrofit Project

9 Table 2

- 2 Modeled Annual Acid Deposition from FCPP in Top 2 cm of Soil from Operation of Units 4 and 5 with SCR installed

Acid Depo sition H 2 SO 4 (g/m 2 /yr) SO 2 (g/m 2 /yr) NO X (g/m 2 /yr) S (g/m 2 /yr) N (g/m 2 /yr) HCl (g/m 2 /yr) HF (g/m 2 /yr) Total H + equivalents /m 2 /yr* S Deposition (H+ equivalents /ha/yr)** N Deposition (kg/ha/yr)**

Maximum 0.071 0.049 0.012 0.048 0.0037 0.0075 0.026 0.0047 29.9 0.037
Average within 10 km Radius 0.0037 0.0069 0.0014 0.0047 0.00043 0.00058 0.0020 0.0018 2.9 0.004

Average within Deposition Area 0.0015 0.0025 0.00051 0.0017 0.00016 0.00027 0.00094 0.0016 1.1 0.002

* Assumes each mole of S results in 2 H + equi valents and each mole of N, HCl, and HF result in 1 H + equivalent. ** Total sulfur or nitrogen deposition from combined sources listed in the table. g/m 2 /yr = grams per meter squared per year kg/ha/yr = kilograms per hectare per year

H+

– Hydronium ion

H 2 SO 4 – Sulfuric acid

HCl

– Hydrogen chloride

HF

– Hydrogen fluoride N

– Nitrogen

NO X – Nitrogen oxides

S

– Sulfur

SO 2 – Sulfur dioxideBiological Assessment for the Four Corners Power Plant SCR Retrofit Project

10 

## 3.0 Species Accounts and Environmental Baseline Conditions

E ight federally endangered, threatened, proposed or candi date species (two plant

, three fish, and three bird species ) have the potential to occur within the Deposition Area

. In order to identify species potentially present within the Deposition Area, vegetation cover types identified by the SWReGAP data within t he Deposition Area were reviewed. Additionally, the existing Habitat Model (AECOM 2013a ), which used modeling and field surveys to characterize baseline habitat conditions in an area that encompasses the Deposition Area

, was used in this analysis

. The base line conditions described resulted from the effects of all past and present activities in the Deposition Area

. Past and present activities in the Deposition Area include urbanization, dryland and irrigated ag riculture

, operation of the San Juan Generating Station, and water diversion s , all of which affect species and their habitat.

The Habitat Model and the subsequent field surveys (AECOM 2013a ) identified areas of expected suitable habitat within the Deposition Area for the eight species. It should be note d that the availability of suitable habitat does not necessarily indicate that the species is present. For example, although the Habitat M odel identified potential habitat for the black

- footed ferret, it is not addressed in this BA because it is considered extirpated in New Mexico by the USFWS , with the last confirmed occurrence doc umented in 1934 (BISON

- M 2012).



### 3.1 Birds

Two federally listed bird species and one bird species proposed for listing may occur along the San Juan River within the Deposition Area : Mexican spotted owl

, southwest willow flycatcher , and yellow

- billed cuckoo

.



### 3.1.1 Natural History and Habitat Association
Mexican Spotted Owl
The Mexican spotted owl was listed as threatened on March 16, 1993 (58 FR 14248

- 14271), and a Recovery Plan was release d on June 6, 1995 (60 FR 29913

- 29951). The US FWS released the final Mexican Spotted Owl Recovery Plan, First Revision (Recovery Plan) in December 2012 ( USFWS 2012). Critical habitat was designated for the Mexican spotted owl in 2004 and includes approximat ely 8.6 million acres on Federal lands in Arizona, Colorado, New Mexico, and Utah (69 FR 53182). According to the Final Recovery Plan (USFWS 2012 ), the primary threats to the Mexican spotted owl population in the U.S. (but likely not in Mexico) have transitioned from timber harvest to an increased risk of stand

- replacing wildland fire.

The Mexican spotted owl is one of three recognized subspecies of spotted owl in North America. The Mexican spotted owl is a permanent resident in the interior mountain ranges of western North America, ranging from southern Utah and central Colorado south through the mountains of Arizona, New Mexico, and extreme west Texas. The species typically occupies old growth forest in mixed conifer, pine

- oak woodland, deci duous riparian, or a combination of these habitats that will support a home range of 1,400 to 4,500 acres (Ehrlich et al. 1988; Gutierrez et al. 1995). An undisturbed core area of approximately 600 acres centered on the nest site is the currently recommend ed disturbance buffer (Gutierrez et al. 1995).

Mexican spotted owls typically inhabit steep canyons with mature or old growth forest, but they also may occur in canyons with steep cliffs and relatively little forest habitat. In the northern portion of the Mex ic an spotted owl’s range, including Utah, Colorado, and parts of far n orthern Arizona and New Mexico owls occur primarily in steep

- walled, rocky canyons ( USFWS 2012 ). These canyon systems vary in the amount of forest cover present, but in general they a re less heavily forested than are canyons occupied farther south. Pinyon

- juniper woodlands and mixed

- conifer forest are prominent cover types used in these canyon systems ( Ganey and Dick 1995 ), but in some cases these canyons are entirely or largelyBiological Assessment for the Four Corners Power Plant SCR Retrofit Project

11 lackin g forest or woodland cover

. Mexican spotted owl habitat typically has a structured canopy, a perennial water source, and a rodent

- dominated prey base of adequate size (Gutierrez et al. 1995).

Mated pairs of owls defend a breeding territory at least during the nesting season (March through August). Clutch size is small (generally 1 to 3 eggs), and eggs hatch in early May. A second clutch may be laid if the first fails. The females brood the young owlets almost constantly the first couple of weeks, then may be away hunting for several hours a day. Owlets fledge at 4 to 5 weeks old (early to mid

- June), and leave the nest before they can fly, moving to the tree branches or the ground while still under parental care. Dispersal from the nest area usually occurs f rom mid

- September to early October. Mexican spotted owls breed sporadically, and not all birds nest every year. Local conditions, particularly for the prey base, may gov ern nesting success (USFWS 2013 a ).

Southwestern Willow Flycatcher

The southwestern will ow flycatcher was listed as endangered, without designated critical habitat, on February 27, 1995 (60 FR 10693

- 10715). Critical habitat was la ter designated on July 22, 1997 (62 FR 39129

- 39147)

. A court decision in 2001 resulted in a subsequent Final Rule on Critical Habitat on October 19, 2005 (70 FR 60885

- 61009). Critical habitat for the southwestern willow flycatcher was recently revised in 2013 ( 78 FR 343

- 534 ). In total, approximately 1,227 stream miles have been designated as critical habitat, with a l ateral extent including riparian areas and streams that occur within the 100

- year flood plain or flood

- prone areas totaling 208,973 acres. A 5

- year review of the subspecies was completed by the USFWS in 2005 ( 73 FR 14995

- 14997).

According to the Final Recovery Plan for the southwestern willow flycatcher (USFWS 2002 a ) , the primary threat to t his species is the extensive loss and modification of breeding habitat with consequent reductions in population levels. Destruction and modification of riparian habitats have been caused mainly by the reduction or elimination of surface and subsurface water due to diversio n and groundwater pumping; changes in flood and fire regimes due to dams and stream channelization; clearing and controlling vegetation; livestock grazing; changes in water and soil chemistry due to disruption of natural hydrologic cycles; and establishmen t of invasive non

- native plants (USFWS 2002 a ). Concurrent with habitat loss have been increases in brood parasitism by the brown

- headed cowbird (Molothrus ater), which inhibit reproductive success and further reduce population levels (USFWS 2002 a , 2013 c ).

The southwestern willow fly catcher is restricted to riparian habitats along rivers, streams, or wetlands (Hiatt and Boone 2003). Four specific types of breeding habitats have been described for the southwestern willow flycatcher. The first is comprised of dense stands of willows 10 to 23 feet in height, with no distinct overstory. This community is often associated with sedges, rushes, or other herbaceous wetland plants. A second habitat type includes nearly monotypic, dense stands of saltcedar or Russian olive up to 33 feet in heigh t. These species form a dense, closed canopy, with no distinct understory layer. Native broadleaf

- dominated communities composed of a single species (often a willow species) or mixtures of native broadleaf trees and shrubs (cottonwood, willows, boxelder, a sk, alder) form a third habitat type. The final habitat type is a mixture of native and exotic riparian species (Sogge et al. 1997).

Regardless of the vegetation species composition, all of these habitats share common structural characteristics. Occupied southwestern willow flycatcher habitats always have dense vegetation in the interior, and dense areas are often interspersed with small clearings, open water, or areas of sparse shrubs. Habitat patches can vary in size and shape, with some occupied areas b eing relatively dense, linear, contiguous stands, and others being large, irregularly shaped mosaics of dense vegetation intermingled with open areas. Habitat patch sizes can range from as little as 2 acres to several hundred or a thousand acres. Southwest ern willow flycatchers may occur at elevations as high as 7,875 feet above mean sea level . They also inhabit willow or cottonwood riparian areas that extend out into desert regions (Terres 1980). Migration and winter habitat could differ from breeding habi tat for this subspecies. During migration, riparian habitat along major southwestern drainages is commonly utilized, but a close association with water may not always exist. These drainages might be considered stopover areas, and could be very important mi gration habitat for the southwestern willow flycatcher (USFWS 2002 a ).Biological Assessment for the Four Corners Power Plant SCR Retrofit Project

12 Egg

- laying can begin as early as late May, but typically occurs in early to mid

- June. Clutch size is usually 3 or 4 eggs for initial nests. Incubation last between 12 and 13 days from t he date the last egg is laid, and eggs typically hatch within 24 to 48 hours of each other. Chicks can be present in the nest mid

- June through early August and fledging typically ensues from late June through mid

- August. Adults then depart from breeding ar eas between mid

- August to mid

- September (Sogge et al. 1997).

Yellow

- billed Cuckoo

In 1998

, the USFWS received a petition to list the yellow

- billed cuckoo under the ESA stating that the species is endangered in a significant portion of its range and that t his range is coterminous with a valid subspecies, the western yellow

- billed cuckoo ( Coccyzus americanus occ identalis ). In 2001, the USFWS published a 12

- month petition finding ( 66 FR 38611

- 38626) concluding that the western yellow

- billed cuckoo constituted a valid distinct population segment ( DPS ) and that the DPS was warranted for listing; however, this action was precluded by higher priority listing action s , and the DPS was placed on the candidate species list. The Western U.S. DPS of the yellow

- billed cu ckoo was proposed for listing as threatened on October 3, 2013 (78 FR 61621

- 61666 )

.
According to the speci es assessment for the yellow

- billed cuckoo (USFWS 2013 c), the primary threat to t his species is similar to that listed for the southwestern willow flycatcher above, including extensive loss and m odification of breeding habitat with consequent reductions in population levels. Destruction and modification of riparian habitats have been caused mainly by reduction or elimination of surface and subsurface water due to diversio n and groundwater pumping; changes in flood and fire regimes due to dams and stream channelization; clearing and controlling vegetation; livestock grazing; changes in water and soil chemistry due to disruption of natural hydrologic cycles; and establishmen t of invasive non

native plants (USFWS 2002 a ). Concurrent with habitat loss have been increases in brood parasitism by the brown

- headed cowbird (Molothrus ater), which inhibit reproductive success and further reduce population levels (USFWS 2002 a , 2013 c ). Additionally, the use of pesticides is suspected to have some adverse impact on the yellow

- billed cuckoo but has not been proven (USFWS 2013 c ).

The species formally ranged throughout much of North America from southern Canada, south to northern Mexico ( 66 FR 38611

- 38626 ). However, in recent years, the species’ dis tribution in the west has declined precipitously throughout its range and the species is nearly extinct west of the Continental Divide, primarily due to habitat loss (BISON

- M 2002). Based on historic accounts, the western yellow

billed cuckoo was once wide spread and locally common in California and Arizona, locally common in a few river reaches in New Mexico, locally common in portions of Oregon and Washington, and generally local and uncommon in scattered drainages of arid and semiarid portions of western Colorado, western Wyoming, Idaho, Nevada, and Utah (USFWS 2013b).

In the arid w est, yellow

- billed cuckoos are riparian specialists (Floyd et al. 2007). Cuckoos typically inhabit large stands of mature, dense willows, but they also use smaller patches of m esquite, tamarisk, hackberry, and other wood vegetation (Floyd et al. 2007). Cuckoos typically do not utilize conifer and mixed broadleaf/conifer forests and/or urban areas (Bennet and Keinath 2003). Western yellow

- billed cuckoos typically breed in large b locks of riparian habitat that is characterized by an overstory of cottonwood trees and a dense subcanopy or shrub layer (regenerating canopy trees, willows, or other riparian shrubs) almost exclusively near water ( 66 FR 38611

- 38626). Yellow

- billed cuckoos breed in North America from March through August (BISON

- M 2002).

The western yellow

- billed cuckoo is a long

- distance, complete n eotropical migrant and generally one of the last migrants to arrive on breeding grounds in the U.S. (Hughes 1999) . In San Juan County

, they breed in the summer

. The typical clutch size is 1 to 5 eggs

. The nestling s are fledged from the nest approximately seven days after hatching and migrate south at three to four weeks of age (BISON

- M 2002)

. Cuckoos depart for wintering grounds b eginning in late August to mid

- September . The migratory route of the western yellow

- billed cuckoo is not well known because few specimens collected on wintering grounds have been ascribed to the western or eastern subspecies (Bennett andBiological Assessment for the Four Corners Power Plant SCR Retrofit Project

13 Keinath 2003) . The western yellow

- billed cuckoo likely moves down the Pacific Slope of Mexico and Central America to northwester n South America

.



### 3.1.2 Potential Presence in the Deposition Area
Mexican Spotted Owl
Approximately 800 acres of potential nesting habitat for the Mexica n spotted owl occurs within the Deposition Area (AECOM 2013c ).

Southwester n Willow Flycatcher and Yellow

- billed C uckoo

T he riparian areas along the San Juan River contain suitable habitat for numerous sensitive species according to the Habitat Model. The s outhwestern willow flycatcher and yellow

- billed cuckoo are associated with riparian habitats. Approximately 6,700 acres of suitable habitat exist within the Deposition Area (AECOM 2013c ).

The southwestern willow flycatcher is a breeding resident in San Ju an County, New Mexico, with small breeding populations occurring along the San Juan River drainage (USFWS 2002a ). Occurrence records exist for this species within the Deposition Area (NNNHP 2011).

The BLM Farmington Field Office documented occurrences of y ellow

- billed cuckoos at five of their San Juan River tract management parcels during 2002 and 2003 surveys between the Hogback and Bloomfield, New Mexico. However, given this species documented use of saltcedar, this species could occur in the Deposition A rea where saltcedar and other riparian vegetation occur.



### 3.2 Fish

Two federally listed fish species and one candidate fish species may occur within the San Juan River within the Deposition Area : Colorado pikeminnow, razorback sucker, and roundtail chub.



### 3.2.1 Natu ral History and Habitat Association

Colorado Pikeminnow

The Colorado pikeminnow was designated endangered prior to the implementation of the ESA in 1973 (32 FR 4001, March 11, 1967 ). Critical h abitat was designated on March 21, 1993 (59 FR 13374

- 13400). Habita t requirements for this species vary depending on the life stage and time of year. Young

- of

- the year (YOY) and juveniles prefer shallow backwaters, while adults prefer pools, eddies, and deep runs ( Miller et al. 1982 ). Adults seem to prefer depths of about 2 to 7 feet, velocities of 0 to 0.2 feet per second, and boulder/silt substrates (Valdez et al. 1982). Juveniles and YOY usually are found over silt or sand bottoms with minimal current (Tyus et al. 1982). During peak runoff in the spring and early summer

, fish usually move into backwater areas of flooded riparian zones to avoid swift velocities, feed, and prepare for the upcoming spawning period (Valdez and Wick 1983). As adults mature, they become highly mobile during the spawning period, which occurs af ter peak runoff from mid

- June to mid

- August. Larvae drift downstream from spawning sites beginning in late June and continue until late August.

According to the r ecovery goals for the Colorado p ikeminnow (USFWS 2002b )

, threats to t his species include streamflow regulation, habitat modification, competition with an d predation by non

- native fish species, and pesticides and pollutants. Of these threats, streamflow regulation and associated habitat modification as a result of the construction of water management structures (i.e., dams, reservoirs, weirs) are identified as primary threats to fish populations, while the competition and predation due to non

native fish is also a major threat (USFWS 2002 b ). The potential role of pesticides and pollutants in

s uppressing populations of the Colorado pikeminnow is not well understood (USFWS 2002 b ). Pollutants identified in the recovery goals include petroleum products, heavy metals (e.g., mercury, lead, zin c , copper), non

- metals (i.e., selenium ), and radionuclides

. Impacts to t his fish species as a result of acid deposition have not been identified.Biological Assessment for the Four Corners Power Plant SCR Retrofit Project

14 The Colorado pikeminnow has been documented within the San Juan River from Shiprock, New Mexico, to the Lake Pow ell inflow (USFWS 2002b ). Lake Powell defines the downstream distribution with irrigation diversions blocking an y upstream movement (USFWS 2002b ).

Critical habitat for this species is found within the Depos ition Area (59 FR 13399

- 13400) . In San Juan Count y, New Mexico, critical habitat is located within the San Juan River and its 100

- year floodplain, extending from the State Route 371 bridge near Farmington, New Mexico to Neskahai Canyon in the San Juan arm of Lake Powell up to the full pool elevation.

Ra zorback Sucker The razorback sucker was listed as endangered on October 23, 1991 (56 FR 54957

- 54967) with critical habitat designated on March 21, 1994 (59 FR 13374

- 13400). Habitat requirements for this species reflect both riverine and reservoir environme nts. General habitats used by adults include eddies, pools, and backwaters during the non

- breeding period (July through March) (Maddux et al. 1993). Osmundson and Kaeding (1991) summarized seasonal habitat use as follows : pools and eddies from November th rough April, runs and pools from July through October, runs and backwaters in May, and backwaters and flooded gravel pits during June. Juveniles seem to prefer shallow water and minimal flow in backwaters, tributary mouths, off

- channel impoundments, and la teral canals (Maddux et al. 1993). The spawning period for razorback suckers in the Upper Colorado River Basin usually occurs in April through mid

- June. Spawning in the Green River has been documented at the confluence with the Yampa River (Modde et al. 19 96).

According to the r ecovery goals for the razorback sucker (USFWS 2002 c ) , threats to t his species include streamflow regulation, habitat modification, competition with an d predation by non

- native fish , and pesticides and pollutants. Of these threats, streamflow regulation and associated habitat modification as a result of the construction of water management structures (i.e., dams, reservoirs, weirs) are identified as primary threats to these fish populations, while the competition and predation due to non

- native fish is also a major threat (USFWS 2002 c ). The potential role of pesticides and pollutants in s uppressing populations of razorback suckers is not well understood (USFWS 2002 c ). Pollutants identified in the recovery goals include petroleum products, heavy metals (e.g., mercury, lead, zine, copper), nonmetals (i.e., selenium ), and radionuclides

. Impacts to t h is fish species as a result of acid deposition have not been identified.

The razorback sucker is stocked in the San Juan River a location near Shiprock. Designated critical habitat extends from the Hogback Diversion, approximately in the middle of the Deposition Area, to the San Juan arm of Lake Powell (59 FR 13399

- 13400)

.

Roundtail Chub

The Lower Colorado River DPS of the rou n dtail chub is a federal candidate species ( 78 FR 70104, 70126

, 2013). Adult roundtail chubs inhabit the most permanent water in cool to warm water mid

elevation streams, typically using pools and eddi es, adjacent to rapids and boulders. They are often found near cover (e.g.

, rocks, plant roots) and in pools behind irrigation diversions. Juveniles prefer the margins of flowing water and backwater areas. Spawning occurs in late spring over gravel bottoms in runs and pools with ≥ 25

- centimeter ( cm ) water depth. This species is found within the San Juan and Mancos Rivers. Rarely encountered in recent surveys; they have been found from Shiprock to near Lake Powell with mo st between Shiprock and Aneth (River M iles 107

- 140).

According to the listing status for the roundtail chub (USFWS 2013 d ), threats to t his species include streamflow regulation, habitat modification, competition with an d predation by nonnative fish species, and pesticides and pollutants. Pesticide and pollutants were not specifically identified as a threat to the roundtail chub, but the decrease in water quality due to pollutants was identified in the listing status document (USFWS 2013 d ). Impacts to t his fish species as a result of acid deposition have not been identified.Biological Assessment for the Four Corners Power Plant SCR Retrofit Project

15 

### 3.2.2 Potential Presence in the Deposition Area
USFWS (2012) reported that there were no wild roundtail chub, Colorado pikeminnow, or razorback sucker collected during their 2010 collection/monitoring effort; however, stocked Colorado pikeminnow and razorback sucker were collected. One roundtail chub was collected in 2009 and 2008. Prior to these two collections, the next previous collection of roundtail chub occurred during the fall 2002 collection. Colorado pikeminnow and razorback sucker are st ocked in the San Juan River and these stocked populations represent the majority of the fish of these species within the San Juan River (USFWS 2012). Additionally, d ata from the NHNM indicates that the Colorado pikeminnow was identified within 10 km of the FCPP in 2002 (NHNM 2011)

.


### 3.3 Plants
Suitable habitat exists within the Deposition Area for two listed species of plants, the Mesa Verde cactus and the Mancos milk

- vetch ( AECOM 2013 c ).



### 3.3.1 Natural History and Habitat Association

Mancos Milk

- vetch

The Mancos milk

- vetch was listed as federally endangered on June 27, 1985 ( 50 FR 26568

- 26572). Mancos milk

- vetch is a diminutive, tufted perennial growing in clumps up to 30 cm (12 inches [in]) across with a dense crown of persistent spiny leaf stalks; no other mat

- formi ng Astragalus species has persistent, subspinescent petioles (USFWS 2011 a ). Stems are up to 1 cm (0.4 in) long and are crowded with leaves up to 4 cm (1.6 in) long (USFWS 2011 a ). Flower branches support 1 to 3 lavender/purplish flowers with a conspicuous l ighter

- colored spot in the throat of the corolla tube (USFWS 2011 a ). Mancos milk

- vetch flowers in late April and early May (USFWS 2011 a ). Larger plants may produce over 100 flowers in a growing season and fruits mature by mid

- June (USFWS 2011 a ). The fruit is egg

- shaped and laterally compressed measuring about 4.5 millimeters (mm) (0.2 in) long and 2 mm (0.1 in) in diameter (USFWS 2011 a ), and each produces 4 to 9 seeds (USFWS 2011 a ). In New Mexico, monitoring results revealed that it takes two growing season s for seedlings to mature with flowering into the third or fourth year as compared to other species of Astragalus, which typically take one growing season to bloom (USFWS 2011 a ).

According to the final recovery plan for the Mancos milk

- vetch (USFWS 1989) , the primary threats to t his species include the destruction and modification of habitat due to surface disturbance as a result of oil,
gas , and transmission line development and the direct collection of individuals by commercial and private collectors. Acid deposit ion f rom power plant operations has been identified as a pot ential threat; however, there are no data to suggest that acid deposition has actually pose d a threat to t his species (USFWS 1989).

This species occurs on sandstone substrate ledges and mesa tops in cracks or shallow bowl

- like depressions (tinajas) that accumulate sandy soils and rainfall (USFWS 2011 a ). Populations are found along the Colorado Plateau subdivision of the Great Basin Desert of northwestern New Mexico and southwestern Colorado within pinyon

- junipe r woodland and desert scrub communities (USFWS 2011 a ). Potential habitat corresponds to rimrock outcrops of the Point Lookout and Cliffhouse members of the Mesa Verde sandstone series with flat or gently sloping surfaces at an average elevation of 1,854 me ters (m) (5,650 feet [ft]) (USFWS 2011 a ). This species is confined to large sheets of exfoliating whitish

- tan colored sandstone (USFWS 2011 a ) alongside Fraxinus anomala (single leaf ash), Brickellia microphyla var. scabra (scabrous bricklebush), Cercocarpu s intricatus (small leaf mohagany), and Ipomopsis roseata (rosy ipomopsis) (USFWS 2011 a ). Overall cover is very low (less than five percent), and resource competition for all of these species is minimal (USFWS 2011 a ). At a broader landscape scale, dominant plant associates are Achnatherum hymenoides (Indian ricegrass), Gutierrezia sarothrae (broom snakeweed), Yucca angustissima (narrow leaf yucca), and Artemisia tridentata (big sagebrush) (USFWS 2011 a ).Biological Assessment for the Four Corners Power Plant SCR Retrofit Project

16 Mancos milk

- vetch is a narrow endemic known only from the Four Corners region of New Mexico, San Juan County, and adjacent Montezuma County, Colorado. Species distribution closely follows a narrow band of Mesozoic (Point Lookout and Cliff House) sandstone along a 10

- mile section of the Hogback geologic format ion (USFWS 2011 a ). Prior to 1989, there were a total of 13 known populations with 3 of these located on Ute Mountain Ute tribal lands in Colorado (USFWS 2011 a ). Since the completion of the recovery plan in 1989, the Colorado populations have not been monit ored (USFWS 2011 a ). New plots were installed for Bureau of Land Management (BLM) and State of New Mexico lands starting in 1990 (USFWS 2011 a ). Only the Navajo Nation found their 13 previously known populations, along with one new population, allowing for s ome long

- term comparisons to past population numbers (USFWS 2011 a ).

Major individual site differences with regard to Mancos milk

- vetch seedling density and mature plant cover have been observed (USFWS 2011 a ). Despite these differences, it appears that maxi mum population development and density occur on larger, relatively flat surfaces with numerous cracks and tinajas that accumulate soil and rainfall (USFWS 2011 a ). This observation is supported by distinct site differences found between the BLM and State of New Mexico plots.

Mesa Verde Cactus The Mesa Verde cactus was listed as federally threatened on October 30, 1979 ( 44 FR 62471

- 62474). Habitat is primarily salt

- desert scrub communities in the Fruitland and Mancos shale formations, and in the Menefee Forma tion overlying Mancos shale. This species is most frequently found on the tops of hills or benches and along slopes. Mesa Verde cactus is a perennial desert plant that grows slowly and has a lifespan of approximately 20 years (USFWS 2011 b ). It is distingui shed within the Sclerocactus genus by an almost total lack of central spines (0 to 1), but also a sporadic occurrence of a single hooked central spine per areole (USFWS 2011 b ). Stems are mostly pale gray

- green, 3.2 to 11 cm long (1.3 to 4.3 in), an d 3.8 to 8 cm in diameter (1.5 to 3.1 in), with 13 to 17 ribs with spines from 6 to 13 mm (0.2 to 0.5 in) long, in clusters of 8 to 11 (USFWS 2011 b ). Flowers are 1 to 3 cm (0.4 to 1.2 in) wide and 1 to 3.5 cm (0.4 to 1.4 in) long with purple mid

- stripes and golden to cream

- colored margins on the outer tepals (USFWS 2011 b ). Flowers in the southern end of its range tend to have smaller, pinkish flowers (USFWS 2011 b ). Fruits are green becoming tan at maturity, and seeds are dull black 2.5 to 3 mm (~0.1 in) long (USFWS 2011 b ). Average stem length for a mature plant is 9 cm (3.5 in) (USFWS 2011 b ).

According to the final recovery plan for the Mesa Verde cactus (USFWS 2012), the primary threats to
t his species include the destruction and modification of habitat due to surface disturbance as a result of oil, gas

, and transmission line development and the direct collection of individuals by com mercial and private collectors.

At the time of the USFWS Mesa Verde Cactus Recovery Plan (USFWS 1984), the known distribution of Mesa Verde cactus in San Juan County extended from the Colorado/New Mexico bord er east to Waterflow, New Mexico, approximately 15 miles west and 10 miles south of Shiprock, Ne w Mexico (USFWS 1984). There was one isolated population located one mile south of Sheep Springs, New Mexico (USFWS 1984). Three of the five known populations e xist ed on the Navajo Nation and a fourth existed east of the Hogback and north of Waterflow, New Mexico on Bureau of Land Management (BLM) administered lands, Public Service Company of New Mexico lands, and other private lands (USFWS 1984). The 1984 recove ry plan estimated the rangewide population to be approximately 5,000 to 10,000 plants within an estimated 120 x 48 km (75 x 30 miles ) rectangular area (USFWS 2011 b ).

Additional cactus populations and locations have been discovered on Navajo Nation la nds after the plan was finalized in 1984 (USFWS 2011 b ). Distribution within this range is not continuous and is sporadic and widely scattered (USFWS 2011 b ). Density greatly varies within populations with the highest known concentration being a 40 km (25 mi ) swath around Shiprock, New Mexico, which may be an artifact of numerous botanical surveys conducted due to increased development pressures (USFWS 2011 b ). Of the known populations of Mesa Verde cactus, at least 80 percent of these occur on Navajo Nation l ands, 15 percent on Ute Mountain Ute lands, and 5 percent on small blocks of BLM and New Mexico StateBiological Assessment for the Four Corners Power Plant SCR Retrofit Project

17 lands (USFWS 2011 b ). Currently, there are no discoveries known on lands outside of these four landowners (Navajo Nation, Ute Mountain Ute, BLM, and State of New Mexico), but not all habitat potentially suitable for Mesa Verde cactus has been surveyed (USFWS 2011 b ).



### 3.3.2 Potential Presence in the Deposition Area
Modeled p otential habitat for the Mancos milk

- vetch and Mesa Verde cactus is depicted in Figures 3

- 1

a nd 3

- 2

. Based on the model, habitat for the Mancos milk

- vetch is confined to a narrow band located to the west of the FCPP

. Known distributions for the Mancos milk

- vetch are located within a 10 km radius of the FCPP (NMNH 2011 ; NNNHP 2011). Potential occur rence of the Mesa Verde cactus would be limited to suitable habitat within the northwest portion the Deposition Area , as t his species has n ot been reported south of the San Jua n River (Heil 2013).

Field surveys for rare plants were conducted to verify habi tat models and quantify habitat quality in 2012 and 2013 (AECOM 2013a ,d )

. S urveys , where conducted within the Deposition Area, did not locate any populations of Mancos milk

- vetch or Mesa Verde cactus, but did identify suitable habitat for both species with in the Deposition Area (AECOM 2013a,d)

. A p opulation of Mancos milk

- vetch w as located to the west of the Deposition Area along portions of the FCPP transmission lines (AECOM 2013a,d).Biological Assessment for the Four Corners Power Plant SCR Retrofit Project

18 Figure 3

- 1 Potent ial Habitat for Mancos Milk

- vetch in Deposition AreaBiological Assessment for the Four Corners Power Plant SCR Retrofit Project

19 Figure 3

- 2 Potential Habitat for Mesa Verde Cactus in Deposition AreaBiological Assessment for the Four Corners Power Plant SCR Retrofit Project

20 

## 4.0 Effects of the Proposed Action

4.1 SCR Installation

As shown in Figure 2

- 1

, the construction activities would be performed in an industrial area without any habitat or listed species present. Truck traffic may add to the noise level at the plant but that increase would be a small addition in this industrial area. The increased t ruck traffic to deliver sorbent and reagent to the FCPP would occur on paved roads that have varying levels of existing traffic. While there may be an increased potential for collisions with listed species within the Deposition Area due to this additional traffic , the current disruption of species and habitats due to existing traffic levels has already established avoidance of major roads by birds in the Deposition Area. There are no listed mammals that would be affected by traffic.

Materials handling was a nalyzed in the NAAQS modeling prepared in support of the EIS (AECOM 2013b) and determined that projected future changes under the Proposed Action would not exceed the standards

. I t is unlikely that emissions from construction and operation of Units 4 and 5 would adversely affect the environment outside the FCPP fenceline. Therefore, the only potential impacts to listed species and their habitat are those with in the Deposition Area outside the FCPP fenceline

.



### 4.2 Acid Deposition on Soils
Soil acidity affects the chemical properties and leaching potential of other contaminants emitted from the FCPP because metals are less soluble in water as pH increases. If the metals are less soluble, they are less mobile in the soil profile and therefore less biologically avail able to plants and animals. Due to the relatively high alkalinity of all soils within the Deposition Area (median pH of 8.2 based on the soil surveys [ Natural Resources Conservation Service { NRCS } 2009, 2008a,b] and 7.8 for the soil samples collected withi n the Deposition Area in 2013), it was believed at the start of the analysis of impacts that the high buffering capacity of the soils would minimize the effects of acid deposition , and this hypothesis was tested

.
An evaluation of the acid neutralization p otential of the soils was used to determine whether acid deposition would affect species habitats within the Deposition Area. The testing procedure was based on the Sobek method described in “ Field and Laboratory Methods Applicabl e to Overburdens and Minesoils ” ( EPA 1978). The process involves treating the soil sample with a known quantity of standardized HCl and determining the amount of unconsumed acid by titration with standardized sodium hydroxide.

To establish the neutral ization potential of the soils within the Deposition Area, laboratory tests were performed on 17 soil samples collected during the 2013 field sampling effort. Composites of the 30 cm soil depths were thoroughly mixed in proportion to the amount of soil dep th represented (typically 0 to 2 cm, 2 to 15 cm, and 15 to 30 cm). The laboratory test results were checked and validated by AECOM.

To determine whether the quantity of acid deposition coming from the FCPP would affect the pH of the soils within the Deposi tion Area, a comparison of the soil acid neutralizing capacity (ANC) to the maximum deposition of acid

- forming hydronium ions was conducted (see Table 2

- 2 ) . The lowest value for the ANC (6 t/Kt 2 of 0.1 Normal (0.1N) HCl) from the laboratory testing was sel ected for comparison based on the assumption that, if 25 years of acidic deposition would be neutralized without significantly changing the alkalinity in the soil with the lowest measured ANC, then there would be no effect on the other soils in the deposit ion area with more buffering capacity.

2 t/Kt = tons/kiloton = parts pe r thousandBiological Assessment for the Four Corners Power Plant SCR Retrofit Project

21 This evaluation was completed by comparing the total volume of acid deposited in the top 2 cm of soil to the ANC for the same amount of soil. The impact of 25 years of acid deposition from the FCPP on the soil ANC wa s determined using the following basic steps:

• In the top 2 cm of a 1 m 2 area, there are 20,000 cm 3 or 32,000 g (using a typical soil density of 1.6 g/cm 3 ).

• To neutralize the soil with the lowest ANC (6 t/Kt of 0.1 N HCl), it took 2.4 ml of 0.1N HCl p er 2 g or 1.2 ml 0.1N HCl per g.

• To neutralize 32,000 g of soil with the lowest ANC requires 38,400 ml or 38.4 L of 0.1N HCl (32,000 g * 1.2 ml/g 0.1N HCl = 38,400 ml 0.1N HCl)

• 38.4 L of 0.1N HCl contains 3.84 moles (equivalents) of hydronium ions (H + )

• A s shown in Table 2

- 1 , the maximum acid deposition predicted is 0.0047 H + equivalents per square meter per year or approximately 0.119 H+ eq uivalents /m 2 in 25 years.

• Neutralization of the maximum deposition predicted over 25 years would utilize 3 percent o f the acid neutralizing capacity of the soil with the lowest ANC (0.119 H + eq/m 2 /25 years [from deposition] divided by 3.84 H + eq uivalents /m 2 [existing neutralization capacity]).

The use of the buffering capacity for the soil with the lowest ANC, which is the soil that would be the most affected by acid deposition, provides the most conservative estimate of the effect that acid deposition would have on the soil. The calculations of the buffering capacity assumed that all acid deposition would accumulate in the top 2 cm of soil over 25 years, which also results in a conservative estimate because it is likely that some of the acidic deposition would move from the soil surface by erosion or leaching. Most of the soil samples collected from the Deposition Area h ad much higher ANC values (maximum = 174 t/Kt; median = 85 t/Kt), requiring greater amounts of acid deposition to reduce the soil pH. Based on this analysis, it can be concluded that the soil within the Deposition Area has the ability to accept much more a cidic deposition than would be generated by FCPP emissions before any significant change to soil pH would occur.

Soil acidity affects the chemical properties and leaching potential of metals because they are typically less soluble in water as pH increases. If the metals are less soluble, they are less mobile in the soil profile, less likely to leach through the soil into the groundwater, and less biologically available to plants and animals. For example, the Natural Resources Conservation Service (NRCS 2000 ) recommends increasing the pH of contaminated soils to 6.5 or higher to make heavy metals (such as those emitted from the FCPP stack) less available to plants and animals. Because the addition of acid deposition from FCPP stack emissions would not reduce the soil pH to less than 6.5, metals in the soils in the area of highest potential deposition (Deposition Area) would not be more mobile than under current conditions.



### 4.3 Acid Deposition in Surface Water
Between Farmington and Shiprock, the average pH of the San Juan River, where designated critical habitat for the Colorado pikeminnow occurs, is over 8.0 (Bliesner and Lamarra 2004) with average annual flow rates of more than 1,700 cubic feet per second at Farmington (USGS 2013), which is just upstream from the Deposition Area. With the high flows in the San Juan River, the small amount of acid deposition directly onto the river would have little or no effect on the pH of the fish habitat due to the high pH in the stream and the fact that acidic compounds would be diluted by the large amount of water and high flows

.



### 4.4 Particulate Matter
As demonstrated in the air modeling performed in support of the EIS (AECOM 2013b), the NAAQS for PM 10 and PM 2.5 would not be exceeded during future opera tions of Units 4 and 5 as a result of the addition of SCR sytem s. Because the NAAQS are developed to be protective of the environment, it canBiological Assessment for the Four Corners Power Plant SCR Retrofit Project

22 be concluded that the PM emissions will not adversely affect the environment or the populations and habitat of lis ted species.



### 4.5 Plants

4.5.1 Impact Evaluation

Th is discussion focuses on the potential impact of the change in sulfuric acid mist emissions

. There have been limited studies on the effects of sulfuric acid mist on vegetation , especially in the western U.S. where ac id deposition has never been demonstrated to be of concern to the environment

. Compounds containing sulfur and nitrogen, such as SO 2 , NO X , and sulfuric acid, all contribute to acid deposition when concentrations and climatic conditions are “ right ” for acid to form in the atmosphere. One source of information useful for documentation of the effects of acid deposition on plants is a review of multiple studies on t he effects of SO 2 , NO X , and sulfuric acid mist deposition on vegetation summarized by the World H ealth Organization (WHO 2000 )

. One purpose of this document was to develop guidelines in the form of maximum critical loads for the deposition of acid

- forming air pollutants on vegetation (WHO 2000). The WHO (2000) report was developed to evaluate risks to the environment and public health in Europe, which has different climatic conditions from the Deposition Area under analysis in this BA

. B ecause acid deposition in the environment is not identified as a concern, there are no similar studies in the southwe stern U.S. or comparable climates, and details on the effects of acid deposition are not generally measured or reported in this region. Therefore, the threshold values from the WHO report

are the best data available for comparative purposes

.

The effect of SO 2 deposition on vegetation is largely determined by the surrounding environmental conditions (e.g.

, humidity, temperature, and light intensity) (WHO 2000). Environmental conditions such as drought, temperature, genetic factors, and the presence of other air pollutants appeared to affect the potential for injuries or growth weights experienced by plant species. In general, the studies indicated that short

- term peak exposures of plants to acid deposition had limited impact on plant health, and that most ef fects on vegetation were the result of long

- term exposure to levels of SO 2 , NO X , and sulfuric acid mist above what is identified as the critical load.

After acidic mist is deposited on leaf surfaces, evaporation of the associated water will adjust the

conc entrations of the remaining solutes (WHO 2000). Deposition of sulfuric acid mist tends to be greater on forested areas and vegetation at higher altitudes and the effects on vegetation are dependent on the concentration of sulfate in the mist and the length of time of the exposure (WHO 2000). The WHO report bases its sulfuric acid mist guidelines on equivalent particulate sulfate concentrations because the sulfate concentration in the cloud water is difficult to measure.

Annually, the minimum WHO critical l oad guideline value for SO 2 based on effects on terrestrial vegetation is 250 sulfur equivalents per hectare per year

. As shown in Table 2

- 2 , t he estimated maximum annual average SO 2 concentration in the Deposition Area attributed to FCPP emissions was cal culated to be 29.9 sulfur equivalents/ha/yr, well below the threshold in the WHO (2000) report

. The WHO report presents evidence that NO X in rain, clouds, and fog can have adverse effects on vegetation and establishes a threshold for critical levels of nit rogen on vegetation. The minimum guideline value for nitrogen on an annual basis is 5 kg/ha/yr. As shown in Table 2

- 2 , the estimated maximum annual nitrogen deposition from FCPP emissions in the Deposition Area is predicted to be 0.037 kg/ha/yr.

While it i s difficult to translate the potential effects of acid deposition on plants in Europe described in the WHO (2000) report to impacts on southwestern U.S. vegetation, the WHO thresholds provide a quantitative measure for comparison where other data are unava ilable. Major differences in the plant communities and climatic conditions, such as the short stature of vegetation and lack of continuous cloud cover and fog in the Deposition Area, would result in different (and probably less severe) responses to acidic deposition on sensitive plant species. By comparing the acid deposition from FCPP to the WHOBiological Assessment for the Four Corners Power Plant SCR Retrofit Project

23 thresholds for sulfur and nitrogen deposition, it can be shown that the predicted annual deposition of acidic compounds on vegetation in the Deposition Area is a s mall fraction of the lowest critical load value that has been shown to affect plant health.

BLM vegetation transect data for grazing allotments within the Deposition Area can be used to describe current conditions of plant health at a specific point in tim e , and offer additional information . Rangeland health assessments were conducted during the growing season in the following years : 2000 (Cottonwood Arroyo), 2005 (South Hogback), 2010 (North Hogback), 2012 (Twin Mounds), and 2013 (Shumway)

. The BLM vegeta tion transect documentation demonstrated that the rangeland areas in the Deposition Area are, for the most part, considered relatively healthy, based on BLM standards for healthy rangelands, and do not appear to be affected by emissions from the FCPP. Prim ary impacts to rangeland health were identified from invasive species and drought. There is no mention of effects from acid deposition on vegetation in any of the BLM rangeland assessment worksheets.

Additional documentation of vegetative community health is available from the field surveys conducted

as described above in Section 3. 3 .2 . Field surveys were conducted to identify suitable habitat and plant presence, and also quantify habitat quality. The results of the surveys demonstrated that habitat for th e sensitive plants varied from low to high. The areas identified as low quality habitat were due to the areas missing key habitat characteristics such as altitude, range, substrate, or topography. No areas were identified as low quality habitat due to effe cts of acid deposition from the FCPP

.



### 4.5.2 Determination

No adverse effects on soils or the ecosystem would result from FCPP SCR Retrofit Project

- related construction, operation

, and emissions

. The only potential impacts to vegetation would be indirect, coming from the FCPP emissions deposited in the Deposition Area. All construction activities would occur in an industrial area that is already disturbed and lacks vegetation or potential habitat for listed plants. Acid deposition on plant leaves is expected to b e minimal and will be further reduced by wind and rain throughout the year. Due to the arid environment, lack of continuous cloud cover, and predominance of lower elevation areas near the FCPP , effects from the acid mist emissions from the FCPP are not ant icipated to impact the vegetation communities and sensitive plant species present in the deposition

area. However, studies regarding the impacts of acid mist emissions on sensitive plant species are limited. T he Proposed Action will not contribute to the p roblems d escribed in Section 3.3.1 that

c ontributed to the listing of these species

. Due to these factors, the acid deposition “ m ay a ffect, but is not likely to adversely affect ” the Mancos milk

- vetch and Mesa Verde cactus or their habitats, resulting from the installation and operation of the FCPP SCR Retrofit Project.



### 4.6 Birds and Fish

4.6.1 Impact Evaluation
Similar to the impact analysis of plant species, there have been limited studies on the effects of sulfuric acid mist on wildlife and fish species. The presence of feathers is likely to limit any direct exposure of birds to acid deposition. Acid deposition on plant leaves is expected to be minimal, and will be reduced by wind and rain throughout the year, making impacts from ingestion of plants within the Deposition Area negligible. The small amount of acidic deposition would not likely accumulate in local water bodies and would be diluted due to stream flows and turnover of lake water, resulting in no impacts to fish species. The pH levels in the San Juan River within the Deposition Area have frequently above 8

, and would likely need a substantial amount of acidic deposition to reach a leve l of concern . F ederal ambient water quality criteria recommends a pH range of 6.5 to 9 for aquatic organisms ( EPA 2009).



### 4.6.2 Determination
No adverse effects on soils, water bodies, or the ecosystem would result from FCPP SCR Retrofit Project

- constructio n, operation

, and related emissions

. All construction activities would occur in anBiological Assessment for the Four Corners Power Plant SCR Retrofit Project

24 industrial area that is already disturbed and lacks vegetation or potential habitat for listed birds and fish. The only potential impacts to birds would be indirect, coming from the FCPP emissions deposited in the Deposition Area. Therefore, the ecosystem within the Deposition Area would not be altered by the small increase in acidic dep osition

. However, there is a lack of research on the effects of sulfuric acid mist on wild life and fish species. T he Proposed Action will not contribute to the p roblems d escribed in Section s 3. 1 .1 and 3.2.1 that c ontributed to the listing of these species

. Due to these factors, the acid deposition

“ m ay affect, but is not likely to adversely affect ” federally listed endangered, threatened, or candidate wildlife and fish species or their habitats

, resulting from the installation and oper ation of the FCPP SCR Retrofit Project.Biological Assessment for the Four Corners Power Plant SCR Retrofit Project

25 

## 5.0 Cumulative Effects

Cumulative effects are defined in the ESA Section 7 Consultation Handbook (USFWS 1998) as the incremental impacts of future state, private, or Tribal activities that are reasonably certain to occur within the project area or proximity to the project area . Future EPA actions that are unrelated to the Proposed Action are not considered in this section because they would be subject to separate consultation pursuant to Section 7 of the ESA.

T he impacts discussed in this BA are those attributable to the increases in H 2 SO 4 mist, PM 10 , and PM 2.5 emissions from the installation of SCR systems at the FCPP. These analyses did not account for the reduction in emissions related to the shutdown of Units 1 through 3. Including the shutdown of Units 1, 2, and 3, the p roject will result in the following actual emission changes (AECOM 2014):

• NOx

— 34,000 tpy decrease

• SO 2— 3,100 tpy decrease

• PM

— 650 tpy decrease

• PM 10

— 217 tpy decrease

• PM 2.5

— 128 tpy decrease

A wide variety of activities that may contribute to the loss of a federally listed species are known to occur in the project region. These activities include but are not limited to energy development, mining, recreation, human population expansion, irrigation and water diversion activities, agriculture, livestock grazing, and introductions of non

- native wildlife, plant, or aquatic species. Ma ny of these activiti es are expected to continue on tribal, state and private lands within the habitat and known range of various federally listed wildlife, fish, and plant species, and could contribute to cumulative effects to the species within the project area. Species with small population sizes, endemic locations, or slow reproductive rates, generally would be more susceptible to cumulative effects. In general, the severity of the cumulative effects would depend on factors such as the sensitivity of the species impacted, seasonal intensity of use, type of project activity, and physical parameters (e.g., topography). Details regarding specific cumulative effects to the federally listed species identified as potentially occurring within the P roject area are discussed below.

Mesa Verde Cactus and Mancos Milk

- vetch

There are no known occurrences of threatened, endangered, or candidate plant species within the Deposition A rea. F uture activities that may impact suitable habitat for these species include oil and gas exploration and development, mining, fire management, livestock grazing, noxious weed management, and agricultural activities. These activities may result in the disturbance of habitat which may lead to the indirect loss of individual plants

.

Mexican Spotted Owl, Southwester n Willow Flycatcher, and Yellow

- billed C uckoo Reasonably foreseeable future activities that may impact threatened, endangered, or candidate bird species include oil and gas exploration and development, mining, fire management, livestock grazing, noxious weed management, utility and agricultural activities. These activities may result in the disturbance of habitat which may lead to the indirect loss or the direct loss of individual birds as a result of vehicle collisions, loss of ne sts, etc.Biological Assessment for the Four Corners Power Plant SCR Retrofit Project

26 Colorado Pikeminnow, Razorback Sucker, and Roundtail Chub
Reasonably foreseeable future activities that may impact sensitive fish species and suitable habitat include water depletions, surface disturbance, and potential water quality effects associated with portions of the San Juan River. These activities may result in the indirect loss or the direct loss of individual species as a result of water toxicity.Biological Assessment for the Four Corners Power Plant SCR Retrofit Project

27 

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