APPENDIX G

Biological Assessment and Evaluation 
BIOLOGICAL ASSESSMENT

FOR THE PROPOSED

DESERT ROCK ENERGY PROJECT

PREPARED FOR: 

BUREAU OF INDIAN AFFAIRS

NAVAJO AREA OFFICE

GALLUP, NEW MEXICO

AND

U.S. FISH AND WILDLIFE SERVICE

ALBUQUERQUE ECOLOGICAL SERVICES FIELD OFFICE

ALBUQUERQUE, NEW MEXICO

PREPARED BY: 

ECOSPHERE ENVIRONMENTAL SERVICES

4801 N. BUTLER SUITE 15101 

FARMINGTON, NEW MEXICO 87401 

2257 MAIN AVE., PATIO LEVEL

DURANGO, COLORADO 81301 

APRIL 2007 
ii

TABLE OF CONTENTS

1.0 Introduction........................................................................................................................ 1 

2.0 Description of Proposed Action ........................................................................................ 1 

2.1 Power Plant ..................................................................................................................... 1 

2.2 Access Road.................................................................................................................... 4 

2.3 Transmission Lines ......................................................................................................... 4 

2.4 Water Well Field............................................................................................................. 5 

3.0 General Mitigation Measures............................................................................................... 6 

4.0 Description of the Analysis Area ...................................................................................... 8 

4.1 Physical Characteristics of the Analysis Area ................................................................ 8 

4.1.1 Climate........................................................................................................................ 8 

4.1.2 Topography................................................................................................................. 9 

4.1.3 Geology....................................................................................................................... 9 

4.1.4 Soils............................................................................................................................. 9 

4.1.5 Water Resources ......................................................................................................... 9 

4.2 Biological Characteristics of the Analysis Area ........................................................... 11 

4.2.1 Vegetation................................................................................................................. 11 

4.2.2 Wildlife ..................................................................................................................... 13 

5.0 Description of Listed Species and Designated Critical Habitats................................. 13 

5.1 ESA Listed Species With Potential to Occur in the Analysis Area.............................. 14 

5.2 ESA Listed Species Eliminated From Detailed Evaluation.......................................... 14 

5.3 Designated Critical Habitat in the Analysis Area......................................................... 15 

5.3.1 Colorado Pikeminnow .............................................................................................. 15 

5.3.2 Razorback Sucker ..................................................................................................... 15 

6.0 Effects of the Proposed Action........................................................................................ 16 

6.1 Evaluating Risk of Particulates to Plants, Soil Invertebrates and Wildlife................... 16 

6.1.1 Screening................................................................................................................... 17 

6.1.2 Risk-based Assessment............................................................................................. 17 

6.1.3 Risk Estimates........................................................................................................... 20 

6.1.4 Risk Estimate Results ............................................................................................... 21 

6.2 Air Quality Effects........................................................................................................ 22 

6.3 Water Quality Effects ................................................................................................... 27 

6.3.1 Surface Water Quality............................................................................................... 27 

6.3.2 Ground Water Effects ........................................................................................... 31 

6.4 Infrastructure Related Effects ....................................................................................... 32 

6.5 Effects to Raptors and Migratory Birds........................................................................ 35 

6.6 Federally Listed Species Effects................................................................................... 36 

7.0 Summary of Determinations of Effect ........................................................................... 52 

7.1 Determinations of Effects for ESA Listed Species....................................................... 52 

7.2 Cumulative Effects........................................................................................................ 53 

9.0 Literature Cited and References.................................................................................... 57 
Biological Assessment of the Desert Rock Energy Project ii

APPENDICES

Appendix A Regulatory Agency Correspondence 

USFWS Communications.........................................................................A-1 

NNHP Communications...........................................................................A-2 

Appendix B Biological Evaluation.............................................................B-1 

Appendix C Ecological Risk Assessment (excerpt).........................................C-1 

LIST OF TABLES

Table 3-1. Maximum Projected Disturbance in Acres to Vegetation Communities for the 

Proposed Action. Desert Rock Energy Project 2007................................................................... 12 

Table 4-1. Species listed by the USFWS under the authority of the ESA with Potential to Occur 

in San Juan County, New Mexico, but Eliminated from Further Analysis. ................................. 14 

Table 5-1 Risk Estimate Results in Hazard Quotients (HQs) for Plants and Soil 

Invertebrates. Desert Rock Energy Project.................................................................................. 21 

Table 5-2 Risk Estimate Results in Hazard Quotients (HQs) for Plants and Soil 

Invertebrates. Desert Rock Energy Project................................................................................... 21 

Table 5-3. Summary of Maximum Potential Criteria Pollutant Emissions in Tons Per Year (typ) 

from Proposed Desert Rock Energy Project Power Plant (URS 2007) ........................................ 24 

Table 5-4. Estimated Emission Rates in Pounds per Ton (lb/ton) and Grams per Second (g/s) for 

Selected Air Toxics from the Proposed Desert Rock Energy Project Power Plant. (URS 2007). 25 

Table 5-5. Modeled Concentrations and Deposition Rates for Selected Air Toxics (2003) (URS 

2007) ............................................................................................................................................. 28 

Table 6-1. Summary of the Preliminary Determinations of Effect on Federally Listed Species. 52 

LIST OF FIGURES

Figure 1. Desert Rock Energy Project proposed action................................................................. 3 

Figure 2. Transmission Line proposed San Juan River crossing, looking across U.S. Highway 64 

onto the floodplain. ....................................................................................................................... 10 
Biological Assessment of the Desert Rock Energy Project, April 2007

1.0 Introduction 

The purpose of this Biological Assessment (BA) is to provide information about the potential 

environmental effects that development of the Desert Rock Energy, LLC proposed Desert Rock Energy 

Project would have on federally endangered, threatened, and candidate species. Threatened and 

endangered (T&E) species are managed under the authority of the Endangered Species Act (ESA) of 

1973 (PL 93-205, as amended). The ESA requires federal agencies to ensure that all actions which they 

authorize, fund, or carry out are not likely to jeopardize the continued existence of any endangered or 

threatened species, or result in the destruction or adverse modification of their critical habitat. 

This BA is the means to review, analyze, and document the direct, indirect, interrelated, interdependent 

and cumulative effects on federally listed endangered, threatened, or candidate species, and critical 

habitats thereof as a result of development of the proposed Desert Rock Energy Project. 

This BA is intended to review the proposed action in sufficient detail to evaluate whether implementation 

of the proposed action would affect any species that are listed under the ESA, their critical habitats or any 

species proposed for listing. To achieve this objective, this BA reviews the proposed action in sufficient 

detail to identity the level of effect that would occur to each species evaluated. One of three possible 

determinations will be chosen for listed species based on the best available scientific literature, a thorough 

analysis of the potential effects of the project, and the professional judgment of the wildlife and fisheries 

biologists and ecologists who completed the evaluation. The three possible determinations are as follows: 

• “No effect” – where no effect is expected; 

• “May affect, not likely to adversely affect” – where effects are expected to beneficial, 

insignificant (immeasurable) or discountable (extremely unlikely); and 

• “May affect, likely to adversely affect” – where effects are expected to be adverse or detrimental. 

2.0 Description of Proposed Action 

Desert Rock Energy, LLC is proposing to construct and operate a coal-fired power plant that would 

produce up to 1,500 MW gross (1,366 MW net) of electricity. The proposed facilities include up to two 

750-MW generation units, as well as a plant-cooling system, coal-handling facilities, power transmission 

interconnection facilities, a water-supply system, access to the plant site, waste-management operations 

and other ancillary facilities. The proposed action is summarized below in terms of the required facilities. 

The proposed power plant is located approximately 30 miles southwest of Farmington in San Juan 

County, New Mexico and is entirely within the boundaries of the Navajo Nation. More detailed 

information on the proposed action, including details on project construction, plant operation, 

maintenance, and decommissioning is provided in the DEIS (URS 2007). A map of the project area 

including the proposed action and alternatives is provided as Figure 1. 

2.1 Power Plant 

The power plant site would be located within a 592-acre parcel immediately adjacent to and west of the 

existing BHP Navajo Coal Company (BNCC) lease area. Within the parcel, the footprint of the facilities 

would require approximately 160 acres. Facilities within the power plant site (i.e. administration 

building/control center, turbine hall, air-emission control equipment and facilities, maintenance shop, 

etc.) and operation of the plant are described in more detail in the DEIS (URS 2007). Up to 1.2 million 

tons of earth material is anticipated to be removed for the construction of the plant. The cut-and-fill 

activities, conducted using scrapers or excavators, would be balanced over the site such that soil would 
Biological Assessment of the Desert Rock Energy Project, April 2007 2

not need to be imported or exported. The plant site would be surrounded by fencing for security and 

safety purposes and regular access to the plant would be through a primary gate with security controls. 

The power plant would have a 50-year design life without major capital improvements. 

The power plant, proposed as a mine mouth operation, would be fueled by sub-bituminous coal provided 

by the adjacent resources of the BNCC Lease Area. Operation of the power plant would require up to 6.2 

million tons of coal per year. The coal would be delivered from the BNCC Lease Area to the power plant 

via conveyor. 

State-of-the-art emission controls would be used to minimize emissions of potential air pollutants. Air 

pollution controls for the pulverized coal-fired boilers would consist of the following: 

• Low nitrogen oxide (NOx) burners and selective catalytic reduction to control NOx emissions; 

• Low sulfur coal and wet flue gas desulfurization to control sulfur dioxide (SO2) emissions; 

• Wet flue gas desulfurization and a wet stack to control acid gas emissions, including sulfuric 

acid mist; 

• Wet flue gas desulfurization to control mercury (Hg) emissions. Activated carbon and hydrated 

quicklime injection to be installed before the fabric filter baghouse if needed for additional 

reductions, with secondary reductions in sulfur dioxide (SO2) emissions and sulfuric acid 

(H2SO4) mist; 

• A fabric filter to control particulate emissions; and 

• High efficiency combustion to control carbon monoxide (CO) and volatile organic compound 

emissions. 

Highly efficient supercritical boilers would operate at high temperatures (net heat rate of 8,792 Btu 

[British thermal unit] per kilowatt hour) and pressure to make steam to turn a steam turbine connected to 

a generator that would produce the electricity. Steam exhausted from the turbine would be cooled by a 

Heller natural-draft cooling system. This type of cooling system uses 80 percent less water than 

conventional mechanical-draft cooling systems. No cooling pond would be required. 

The power plant would have a 50-year design life without major capital improvements. At the end of its 

useful life, the power plant and all associated facilities would be decommissioned. All structures and 

equipment at the site would be dismantled and removed. All wells would be decommissioned and 

abandoned in accordance with Navajo Nation procedures and regulations. Following removal and 

abandonment of facilities, any areas disturbed would be rehabilitated as near as possible to their original 

condition including all areas of the BNCC Lease Area disturbed by mining activities. All mining areas 

associated with Desert Rock will be reclaimed per the terms and conditions of BNCC’s Surface Mining 

Control and Reclamation Act (SMCRA) permit as administered by Office of Surface Mining (OSM). 

Coal from the BNCC mine lease would transported via conveyor belt to a coal processing plant located 

within the BNCC mine lease area IV North. The proposed coal preparation facilities would require 

approximately 16.4 acres within a 101 acre parcel. 
Biological Assessment of the Desert Rock Energy Project, April 2007 3

Figure 1. Preferred Alternative including sub-alternatives for the proposed Desert Rock 

Energy Project. 
Biological Assessment of the Desert Rock Energy Project, April 2007 4

2.2 Access Road 

Although existing access roads and 2-tracks are available within the project area and along proposed 

utility and transmission corridor alignments, a new permanent access road to the proposed plant site is 

proposed. The proposed road alignment is approximately 3.5 miles in length, requiring 32 acres of new 

ground disturbance. This access road would spur off of the existing Burnham Road that currently crosses, 

in a north-south direction, Areas V and IV of the BNCC mine lease. 

2.3 Transmission Lines 

The proposed transmission lines would extend from the proposed plant site to the existing Arizona Public 

Service (APS) Four Corners Generating Station (Segments A or B and Segment C). After leaving the 

Four Corners Generating Station, the proposed transmission alignment would continue northward 

(Segment D) crossing the San Juan River and interconnecting with the proposed Navajo Transmission 

Project (NTP). There are two sub-alternative corridors being considered in the DEIS for the 

southernmost portion of the transmission alignment: Segments A and B (described below). With the 

exception of Segment D, which is proposed within a 250 ft-wide right-of-way (ROW), all other 

alternative transmission corridors would be within a 500-ft wide ROW. 

Segment A, the preferred alternative, would leave the plant site and would parallel the eastern side of the 

Chaco River, connecting with Segment C after 8.3 miles. The ROW for this sub-alternative would 

require 503 acres. Sub-alternative Segment B would leave the plant site to the west, cross the Chaco 

River then parallel the western side of the Chaco River continuing northward and crossing the Chaco 

River again before connecting into Segment C after 11.1 miles. The ROW for this alternative would 

require approximately 672 acres. Segment C would be 6.2 miles in length requiring a 375 acre ROW, 

whereas Segment D is 10.8 miles in length and would require a 372 acre ROW. This segment would cross 

the San Juan River and continue northward to tie into the currently proposed NTP. There are no subalternatives considered for transmission Segments C and D. 

Segments A or B would consist of 2 single-circuit 500kV transmission lines. Segment C would consist of 

1 single-circuit 500kV transmission line, which would parallel an existing 230kV line. Segment D would 

also consist of 1 single-circuit 500kV transmission line paralleling an existing 230kV line. All 

transmission line segments would be self-supporting, four-legged, steel-lattice tower structures 

approximately 135 feet in height with 1,200-1,600 feet of spacing between individual structures. 

At each tower site, leveled areas, or pads, approximately 30 feet by 40 feet would be needed to facilitate 

the safe operation of construction equipment, such as cranes. At each structure site, a work area of 

approximately 200 by 200 feet would be required for the location of structure footings, assembly of the 

tower, and equipment maneuvers. The work area would be cleared of vegetation only to the extent 

needed. After construction, disturbed area not needed for normal maintenance of the transmission line 

would be graded to blend as near as possible with the natural contours, and revegetated with indigenous 

plant species. Areas would be reseeded prior to the season(s) when precipitation is normally received. 

Pilot lines would be pulled (strung) from structure to structure by helicopter and threaded through the 

stringing sheaves at each tower. Following the pilot lines, a larger diameter, stronger line would be 

attached to conductors to pull them through. Conductors and ground wires would be strung using 

powered pulling equipment at one end and powered tensioning equipment at the other end of a conductor 

segment. Sites for tensioning equipment and pulling equipment would be approximately 3 miles apart. 

The tensioning site would be an area approximately 200 by 200 feet. The pulling site would require 

approximately half the area of the tension site. 
Biological Assessment of the Desert Rock Energy Project, April 2007 5

During pre-design project development activities, a series of preexisting roads were field verified and 

mapped for access to proposed transmission tower sites resulting in selection of routes that avoided 

disturbance of culturally and biologically sensitive areas. Existing roads will be used to the greatest extent 

possible; however some overland access on undisturbed areas would be required. It is expected that all 

biological and cultural resources of importance along or within all roads used for the project will be 

inventoried and monitored by a professional biologist or archaeologist prior to construction related 

activities and that these resources will be avoided during long term maintenance activities of the project. 

2.4 Water Well Field 

The average annual water consumption demand of the Desert Rock Energy Project is estimated to be 

4,500 acre-feet (ac/ft) per year, or 2,795 gallons per minute (gpm), of continuous flow for a period of 40 

consecutive years. An additional 450 acre-feet per year would be available to meet Navajo municipal 

demand for a total of 4,950 ac/ft per year. The proposed and alternative water sources would be 

groundwater from the Morrison aquifer. Based on evaluations of the hydrogeologic characteristics of the 

Morrison aquifer, it was estimated that 10 to 20 new production wells could meet this anticipated water 

demand (URS 2007). Water from the Morrison aquifer was identified as suitable for industrial use 

through a study by URS in September 2005 and amended in September 2006. Data for the study came 

from previous studies, well data from Navajo Department of Water Resources and water quality field 

tests. 

Two sub-alternate water well field locations are being evaluated in the DEIS and in this BA. The 

preferred alternative Water Well Field B would include 13 wells located within the 592-acre power plant 

facility site, as well as an additional 7 wells spaced at 1-mile intervals along Segment A of the proposed 

transmission line corridor. Each well would be networked to the water-transmission pipeline mains that 

would deliver the water to the onsite 2.5-million gallon water-storage tank. Each well would be equipped 

with a submersible pump powered by an electric motor. The wells would be controlled via telemetry by 

the water level in the regulating/storage reservoir. The telemetry system would likely be connected by 

fiber optic cable buried in the pipeline trench. The sub-alternative Water Well Field A would also be 

comprised of 20 water wells, all within an approximately 2 square mile area. Water Well Field A would 

also require the construction of a 12.4 mile utility corridor/water line. 

Each water production well and associated facilities would be enclosed within an 8-foot-high chain-link 

fence surrounding the well yard, requiring a 100 ft by 100 ft area (approximately 2 acres). The well head 

would be enclosed in a masonry-block structure, or pump house, located within the fenced well yard (as 

needed to protect and secure the well equipment) and meeting the current Uniform Building Code. Within 

the pump house would be the well pump and motor, as well as associated well equipment, such as the 

shut-off valve, check valve, flow meter, air-release valve, electrical equipment, telemetry, and above 

ground piping. The foundation of the pump house would be constructed slightly above surrounding grade 

to minimize flooding potential. 

Individual wells would be connected by collector pipelines to the main utility line, which would extend 

from the Water Well Field to the proposed power plant site. Due to the topographic conditions, the 

pipelines would be pressurized only by the well pumps; no booster-pump station would be required. 

Overhead distribution power lines would be constructed to supply electricity to the wells and would be 

constructed in the same ROW paralleling the main water utility pipeline and collector pipelines. Access to 

the production wells would be needed for construction, operation, and maintenance. Access roads would 

be approximately 15-feet wide and would be gravel roads constructed in accordance with BIA and/or 

Navajo Nation standards. The utility corridor for Water Well Field B would be approximately 12.4 miles 
Biological Assessment of the Desert Rock Energy Project, April 2007 6

in length and constructed within a 100-foot wide ROW requiring a 149.7 acres. Following construction 

the utility corridor would have a permanent 10-foot wide ROW. 

3.5 BNCC Mine Lease 

The power plant would be constructed immediately adjacent to and west of the existing BHP Navajo Coal 

Company (BNCC) lease area which encompasses approximately 13,051 acres. The coal fuel supply 

would be produced and conveyed by a conveyor belt from coal reserve Area IV South, and Area V of the 

BNCC lease area to proposed coal preparation facility located next to the power plant in Area IV North of 

the BNCC lease area. The production phase in Area IV South will last through approximately 2044. At 

that time, the mining operations within the BNCC Lease Area will transition to Area V of the mine lease. 

BNCC holds Surface Permit Number 2838 issued by the New Mexico Office of the State Engineer in 

October 1958. This permit provides BNCC a total diversionary right of 51,600 acre-feet annually, with a 

consumptive right of 39,000 acre-feet annually, for waters drawn from the San Juan River. The additional 

consumption associated with the expansion of the surface mining operations at the Navajo Mine required 

to supply coal to the Desert Rock Energy Project is estimated to be approximately 600 acre-feet annually. 

The additional consumption is within the existing consumptive right and will cause no depletions to the 

San Juan River beyond those authorized under the current water right permit. 

A single public road, referred to as the Burnham Road Realignment, will be re-routed to suit the needs of 

mining operation on the BNCC Lease Area. This road requires re-alignment over its extent within Areas 

III and IV North of the lease to suit the needs of the current BNCC Lease Area operations, regardless of 

the disposition of the Desert Rock Energy Project. Navajo Mine staff have developed a preferred 

alignment and have entered preliminary approval discussions with the Bureau of Indian Affairs (BIA), the 

regulatory authority over the roads in the project area. 

Detailed information concerning the construction and operation of the Desert Rock power plant and 

associated components including the BNCC mine lease are contained within the DEIS (URS 2007). 

3.0 GENERAL MITIGATION MEASURES

The following section discusses mitigation measures that would occur prior to, during, and after 

construction of the proposed action. Measures listed below are in addition to those described under 

individual species that may be affected by the action alternative. General mitigation measures would 

serve to minimize or avoid impacts to federally listed species. Species specific mitigation measures are 

provided in the detailed analysis of impacts in Section 6.0. 

Prior to Construction 

• An Oil and Hazardous Materials Spill Prevention, Control, and Countermeasure Plan shall be 

prepared to address hazardous materials storage and spill prevention. 

• A Storm Water Pollution Prevention Plan shall be prepared and implemented for construction 

activities to control surface runoff, reduce erosion, and prevent sedimentation from entering 

waterbodies during construction. 

• An Environmental and/or Biological Resource Compliance Monitoring Plan shall be prepared for 

all construction projects to ensure implementation of mitigation measures described in pertinent 

resource sections of the DEIS (URS 2007). The plan shall identify the frequency and type of 

monitoring required by qualified natural/biological resources personnel. The plan shall be 

submitted for NNDFW approval prior to any construction.
Biological Assessment of the Desert Rock Energy Project, April 2007 7

• All construction personnel shall attend an environmental protection briefing prior to working on 

any construction site in the project area. This briefing is designed to familiarize workers with 

statutory and contractual environmental requirements and the recognition of and protection 

measures for sensitive vegetation community and wildlife habitats. 

• Protective barriers shall be placed around specified sensitive vegetation community and wildlife 

habitats as identified by the NNDFW. Barriers shall be installed prior to construction and field 

inspected by NNDFW personnel to verify proper placement. 

• Aboveground structures (i.e. transmission towers) shall be sited and designed in order to 

minimize disturbance to sensitive wildlife habitats and to minimize adverse effects to landscape 

features such as topography and vegetation. 

• Imported soils, fills, or aggregates shall be free of deleterious materials (i.e. trash, construction 

debris, noxious weeds). Sources of imported materials shall be submitted for Navajo Nation 

approval prior to construction. 

• A Non-native Species Management Plan shall be prepared prior to the commencement of any 

ground-disturbing activities that specifies the locations and methods for removing non-native 

species, prescriptions for monitoring activities after construction, and reporting requirements. The 

plan shall be submitted for NNDFW approval prior to ground-disturbing activities. 

• A Revegetation Plan shall be prepared for approval by the NNDFW prior to the commencement 

of any ground-disturbing activities that prescribes plant salvage, revegetation, and postconstruction monitoring activities. 

• Preconstruction surveys shall be conducted, as specified by the NNDWF by a qualified biologist 

to identify the number, type, and location of special-status species potentially occur within the 

project area. 

• A construction work schedule shall be prepared for all construction projects that minimizes noise 

and human activity effects on wildlife in adjacent habitats. 

• If any grading, clearing, brushing, or construction occurs during the bird breeding season 

(approximately February 15 through August 31), a qualified biologist shall conduct a survey of 

the habitat to determine whether there are active bird nests in the area, including raptors and 

ground nesting birds. The survey would begin not more than three days prior the beginning of 

work. If an active nest is observed, a minimum 300-foot buffer (500 feet for raptors) would be 

established using temporary fencing. The buffer would be in effect as long as work is occurring 

and until the nest is no longer active. 

During Construction 

• All construction contractors shall implement and comply with requirements of the Oil and 

Hazardous Materials Spill Prevention, Control, and Countermeasure Plan prepared for all 

construction projects. 

• All construction contractors shall implement and comply with operational compliance 

requirements of the Storm Water Pollution Prevention Plan. 

• Construction activities shall be monitored by qualified natural resources personnel as outlined in 

the Environmental and/or Biological Resource Compliance Monitoring Plan. 

• All project construction contractors shall implement and comply with the Non-native Species 

Management Plan prepared for each project component. 

• Vegetation salvage, seed collection, and revegetation shall be implemented as defined in the 

Revegetation Plan. Topsoil shall be salvaged, segregated during storage, and reused in the proper 

location and depth as specified by the NNDFW. 

• All construction activities will be completely confined to the areas of potential ground 

disturbance for each project component as described in in the Desert Rock Energy Project DEIS 
Biological Assessment of the Desert Rock Energy Project, April 2007 8

under the Preferred Alternative (URS 2006) Clearing of vegetation and ground disturbance shall 

be minimized to the greatest extent possible. 

• Stationary noise sources shall be located as far as possible from sensitive wildlife habitat areas. 

On-site work for transmission corridor construction that generates noise levels above 76 decibels 

shall be done between 7:00 a.m. and 7:00 p.m. 

• Excavation sites must be monitored or covered to avoid trapping wildlife, and routes of escape for 

wildlife should be maintained. The construction site shall be inspected daily for appropriate 

covering and flagging of excavation sites. Each morning the project area shall be inspected for 

wildlife trapped in excavation pits. A qualified biologist shall be available to inspect excavations 

before refilling occurs. 

• Proposed electrical transmission and distribution lines will be designed and constructed utilizing 

"raptor-safe" design. The most complete manual on this work is: " Suggested Practices For 

Raptor Protection On Power Lines: The State of the Art in 1996". (APLIC 1996)

Post-Construction 

• All tools, equipment, barricades, signs, surplus materials, debris, and rubbish shall be removed 

from the project work limits upon project completion. 

• The success of revegetation efforts shall be monitored. Plant materials used for revegetation shall 

remain alive and in a healthy, vigorous condition for a period of one year after final acceptance of 

planting. The project site shall be monitored in accordance with the Nonnative Species 

Management Plan and Revegetation Plan. All plants determined to be in an unhealthy condition 

shall be replaced. 

4.0 Description of the Analysis Area 

This section describes components of the environmental setting of the area with potential to be impacted 

by the proposed action. Because a detailed description of the physical and biological characteristics of 

the analysis area is provided in the DEIS (URS 2007), this BA focuses on the physical and biological 

characteristics of the analysis area that have a direct relevance to plant and wildlife species that are listed 

under the ESA. 

To account for factors that may affect ESA listed species, such as emissions, noise and human and vehicle 

presence, the analysis area is defined by a 31-mile (50-km) radius from the proposed Desert Rock Energy 

Project plant site. The 31-mile (50-km) buffer was chosen to be consistent with air quality analyses 

required for major source air quality permitting (U.S. Environmental Protection Agency [USEPA] 2005). 

4.1 Physical Characteristics of the Analysis Area 

4.1.1 Climate 

The climate of the analysis area is classified as arid Continental (BLM 2003). Because of its relatively 

high elevations, San Juan County, New Mexico experiences warm dry summers and cool dry winters 

(Western Regional Climate Center 2006). Average annual temperatures in and near the project area are in 

the low to mid 50’s (degrees Fahrenheit), summer temperatures range from the mid 60’s to the low 90’s 

and winter temperatures range from the low 20’s to the low 40’s (Western Regional Climate Center 

2006). The mean annual precipitation in Shiprock, New Mexico is 7.07 inches (Western Regional Climate 

Center 2006). 
Biological Assessment of the Desert Rock Energy Project, April 2007 9

4.1.2 Topography 

Topography in the analysis area consists of relatively flat to gently rolling hills that slope to the west 

toward the Chaco River. The slopes have a sand- and gravel-covered surface with sparse vegetation. 

Outcrops of resistant rock dip gently to the east, forming west-facing steep-sided escarpments or cuestas, 

and eroded knobs typically less than 50 feet high. The escarpments are cut by washes that have developed 

a west-flowing drainage pattern that meets the meandering channel of the north-flowing Chaco River. 

The topography along the proposed transmission line is comparable until it crosses the San Juan River 

through the water gap in steeply dipping sedimentary rocks of the Hogback monocline. Two welldeveloped washes meander across the BNCC mine leasehold, including Pinabete Arroyo, which crosses 

Area IV South from southeast to northwest and north; and an unnamed wash that crosses the northern part 

of Area V from southeast to northwest. Elevations in the project area range from approximately 5,000 

feet to 5,675 feet. The project area is surrounded by several high elevation areas, including the Chuska 

Mountains in northwest Arizona, Ute Mesa in Colorado and New Mexico, and the San Juan Mountains in 

southwest Colorado and north-central New Mexico. 

4.1.3 Geology 

This BA discusses only those geological formations with relevance to ESA listed species; however, 

detailed description of geological formations present in the project area are provided in the DEIS (URS 

2007). In the context of ESA listed plant and wildlife species, the project area contains 3 significant 

geological formations: Point Lookout Sandstone, Mancos Shale and the Fruitland Formation. Point 

Lookout Sandstone is a member of the Mesa Verde group and is coastal marine sandstone that overlies 

Mancos Shale (URS 2007). Point Lookout Sandstone provides necessary habitat for Mancos milkvetch 

(Astragalus humillimus), a plant species that is listed as Endangered under ESA. Mancos Shale is a thick 

dark grey carbonaceous marine shale with thin interbeds of limestone, siltstone and fine-grained 

sandstone (URS 2007). The Fruitland Formation is the primary coal-bearing formation in the project 

area. This formation contains interbedded sandy shale, carbonaceous shale, sandstone and multiple coal 

layers deposited by rivers (URS 2007). Mancos Shale and the Fruitland Formation provide essential 

habitat for the Mesa Verde cactus (Sclerocactus mesae-verdae), an ESA listed Threatened species. 

4.1.4 Soils 

The project area contains 2 primary soil survey areas that are divided by the Chaco River. The primary 

soil mapping unit east of the Chaco River is the Sheppard-Huerfano-Notal unit, which is found in nearly 

level to gently sloping areas on valley bottoms and nearly level to steep soils on mesas and plateaus (SCS 

1980). The primary soil mapping unit west of the Chaco River is the Major Land Resource Area (MLRA) 

37, that is present along the San Juan River Valley, as well as on mesa tops and plateaus within the 

project area (NRCS 1992). The DEIS provides a more comprehensive description of soils that are present 

in the project area (URS 2007). None of the ESA listed plant and wildlife species with potential to occur 

in the project area is dependent on or limited by specific soil types, but rather are limited by other 

physical or biological resources. 

4.1.5 Water Resources 

The project area lies within the Chaco watershed drainage, that expands through San Juan, McKinley, 

Sandoval, and Rio Arriba counties of New Mexico and Apache County of Colorado. The project area 

contains 3 major bodies of water, the Chaco River, the San Juan River and Morgan Lake. The Chaco 

River is an ephemeral stream with waters flowing in a northwesterly direction towards the San Juan River 

during precipitation events. Precipitation occurs during late summer and early fall with annual averages 
Biological Assessment of the Desert Rock Energy Project, April 2007 10

reaching about 7 inches in Shiprock, yet streamflow varies from year to year due to the streams ephemeral 

qualities (URS 2007). 

The San Juan River originates at the mouth of Navajo Dam in northwest New Mexico and flows 

southwest into Lake Powell. The San Juan River traverses the northern portion of the Desert Rock 

project area and as proposed, Segment D of the transmission line would cross the river. Figure 2 below 

shows the location of the San Juan River crossing The San Juan River is the only natural perennial water 

source in the project area. There are jurisdictional wetlands associated with the San Juan River and its 

floodplain. 

Figure 2. Transmission Line proposed San Juan River crossing, looking south across U.S. 

Highway 64 onto the floodplain. 

The project area contains a single lake, Morgan Lake. Morgan Lake is a man-made lake situated adjacent 

to the Four Corners Generating Station, which utilizes water in the lake to cool its generating units. The 

southwestern corner of Morgan Lake is located within a 1-mile corridor of the southern end of Segment D 

of the proposed transmission line alignment. Jurisdictional wetlands are also present along the margins of 

Morgan Lake (Ecosphere 2006a).

In addition to these large water bodies, the project area also contains scattered wetlands that are fed by 

springs and/or collection of surface water (i.e. stockponds). During the 2006 field season, Ecosphere 

Environmental Services conducted wetland delineations of all potential Waters of the U.S. within all 

project component ROWs and footprints. These surveys identified 2 areas that were characterized as 

wetlands; one near the proposed power plant access road, southeast of the proposed power plant location 

and the other near the Water Well Field (Ecosphere 2006a). There are no jurisdictional wetlands within 

the proposed action area of disturbance. 
Biological Assessment of the Desert Rock Energy Project, April 2007 11

4.2 Biological Characteristics of the Analysis Area 

4.2.1 Vegetation 

Vegetation in the Desert Rock Energy Project analysis area is dominated by Great Basin desert-scrub 

habitats (Dick-Peddie 1993). Great Basin desert-scrub is a cold desert ecosystem dominated by shrubs 

with a sparse understory of forbs and grasses; bare ground occurs in poor, alkaline soils (Fitzgerald et a. 

1994, Dick-Peddie 1993). Vegetative communities within the study area were identified using the 

Provisional Digital Land Cover Map for the southwestern United States (USGS National GAP Analysis 

Program 2006). There are 18 cover types occurring within the analysis area, including two non-vegetative 

cover classes, Open Water and Recently Mined or Quarried (Table 4-1). The vegetative communities with 

the greatest relevance to ESA listed species are semi-desert grasslands, salt desert scrublands, and semidesert shrublands, as well as riparian habitats. The Provisional Digital Land Cover Map for the 

southwestern United States identified areas that have been recently mined or quarried (USGS National 

GAP Analysis Program 2006). Portions of BNCC Permit Areas I, II and have been reclaimed. To more 

accurately describe the study area, data from BNCC’s reclamation efforts were extrapolated to 

characterize reclaimed areas and then categorize into GAP Analysis classifications (BHP Billiton 2004). 

Semi-desert grasslands, salt desert scrublands, and semi-desert shrublands are similar in that they overlap 

somewhat in species composition, but vary by physical structure and vegetative density. For example, 

semi-desert grasslands are often dominated by alkalai sacaton (Sporobolus airoides), galleta (Hilaria 

jamesii) and Indian ricegrass (Stipa hymenoides), but also include scattered shrubs such as saltbush 

(Atriplex spp.), shadscale (Atriplex confertifolia), and greasewood (Sarcobatus vermiculatus). Salt desert 

scrublands are generally dominated by various species of saltbush or greasewood but also include many 

of the same understory grasses and herbaceous forbs as grassland communities. Semi-desert shrublands 

include vegetative communities dominated by shrub species such as rabbitbrush (Chrysothamnus spp.), 

sagebrush (Artemisia spp.), broom snakeweed (Gutierrezia sarothrae), or ephedra (Ephedra spp.) 

Riparian habitats within the analysis area include native, exotic, and mixed native-exotic riparian 

woodlands occurring along perennial and intermittent water sources throughout the region. Native 

riparian woodlands are dominated by cottonwoods (Populus spp.) and willows (Salix spp.), whereas 

riparian exotics include saltcedar (Tamarix chinensis) and Russian olive (Elaeagnus angustifolia). These 

riparian communities are associated with the primary water sources in the project area, the Chaco River, 

the San Juan River and Morgan Lake. 
Biological Assessment of the Desert Rock Energy Project, April 2007 12

Table 4-1. Maximum Projected Surface Disturbance in Acres to Vegetation Communities 

for the Proposed Action. Desert Rock Energy Project 2007. Habitat Type Power Plant Coal Processing Plant Transmission Line A Transmission Line B Transmission Line C and D Access Road 

Water Well Field A Water Well Field A Utility Corridor Water Well Field B BNCC Lease Areas 

Colorado Plateau 

Mixed Bedrock 

Canyon and 

Tableland 1.56 0.00 2.22 0.00 45.81 0.44 2.22 1.60 9.56 5.12 

Inter-Mountain 

Basins Shale 

Badland 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

Colorado Plateau 

Piñon-Juniper 

Woodland 0.00 0.00 1.11 0.00 15.35 1.11 0.00 0.00 10.67 6.00 

Inter-Mountain 

Basins Big 

Sagebrush Shrubland 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.11 

Colorado Plateau 

Mixed Low 

Sagebrush Shrubland 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

Colorado Plateau 

BlackbrushMormon-tea 

Shrubland 0.00 0.00 0.00 0.00 21.35 0.00 0.00 0.00 0.00 0.00 

Inter-Mountain 

Basins Mixed Salt 

Desert Scrub 24.69 10.01 307.13 338.33 235.29 4.45 47.59 61.50 447.68 1332.37 

Inter-Mountain 

Basins Semi-Desert 

Shrub Steppe 46.93 18.01 22.02 30.30 24.69 2.45 3.34 3.18 102.97 475.70 

Inter-Mountain 

Basins Semi-Desert 

Grassland 75.84 70.94 166.80 274.31 298.01 11.34 0.00 31.07 302.90 5893.46 

Rocky Mountain 

Lower Montane 

Riparian 

Woodland/Shrubland 0.00 0.00 0.00 1.60 2.22 0.00 0.00 0.00 0.00 4.89 

Inter-Mountain 

Basins Greasewood 

Flat 0.00 1.78 3.34 24.30 23.80 0.44 836.2 52.40 16.46 379.18 

Southern Colorado 

Plateau Sand 

Shrubland 0.00 0.00 0.00 0.00 4.67 0.00 0.00 0.00 0.00 0.00 

Open Water 0.00 0.00 0.00 0.00 3.34 0.00 0.00 0.00 0.00 3.78 

Barren Lands, Nonspecific 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

Agriculture 0.00 0.00 0.00 0.00 10.90 0.00 0.00 0.00 0.00 0.00 

Recently Mined or 

Quarried 0.00 0.00 0.00 0.00 14.90 0.00 0.00 0.00 0.00 0.00 

Invasive Southwest 

Riparian Woodland 

and Shrubland 0.00 0.00 0.00 0.00 4.67 0.00 0.00 0.00 0.00 0.00 

Invasive Annual and 

Biennial Forbland 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

Total 149 101 503 669 705 20 889 150 890 13,051 

Source: USGS National GAP Analysis Program 2006. Acreages are approximate based on polygon calculations. 
Biological Assessment of the Desert Rock Energy Project, April 2007 13

4.2.2 Wildlife 

The analysis area supports a variety of natural vegetation communities and landscape features that offer a 

diversity of wildlife habitat types, including habitat for an assortment of mammals, birds, reptiles, 

amphibians, fish and invertebrates. While these habitat types correspond with the vegetation community 

types discussed above, they also are defined by a number of distinct landscape features such as washes 

and gullies, rock outcrops and hillsides, cliffs and taluses, and caves. All contribute to the diversity and 

abundance of wildlife in the area as they generally provide a microhabitat for wildlife uniquely adapted to 

or dependent on these features. 

Most wildlife species within the study area are adapted to drought conditions, including sparse vegetative 

cover and limited sources of permanent water. However, perennial sources of water in the study area 

support a relatively high concentration of vegetation and cover that contribute to increased wildlife 

diversity in these areas. While many species of wildlife commonly occur in upland habitats, they also 

depend on riparian-wetland habitat for breeding and cover. The riparian-wetland habitats generally have 

more structured and complex vegetative assemblages, along with higher wildlife diversity than the 

surrounding upland areas. These areas effectively function as movement corridors for mammals and serve 

as congregation and feeding areas for a variety of bird species. Although many of the wildlife species 

present in the project area are habitat generalists, the project area does not support any species for which 

ESA listed plant or wildlife species are obligatorily dependent. 

5.0 Description of Listed Species and Designated Critical Habitats 

The U.S. Fish and Wildlife Service (USFWS) was contacted to request a species list for the Desert Rock 

Energy Project in March 2006. Ecosphere Environmental Services (Ecosphere) was instructed by the 

USFWS to obtain a listing of federally listed, proposed, candidate and species of concern, as well as 

critical habitat present within San Juan County, New Mexico on the USFWS New Mexico Ecological 

Services website. This list contains several Navajo Nation listed species of concern that are also federally 

listed that were identified by the Navajo Nation Department of Fish and Wildlife (NNDFW) in a 

consultation letter received in December 2005. Both the USFWS and NNDFW project initiation 

consultation letters are provided in Appendix A. 

Threatened and endangered species, as well as candidates for listing under ESA are included in Section 

4.1. USFWS Species of Concern, New Mexico State listed species and species included on the Navajo 

Endangered Species List that are not also federally listed are addressed in the project Biological 

Evaluation (BE) provided in Appendix B. 

Information used to compile this section was also gathered from data collected during field-based 

evaluations conducted in between 2004-2006. A review of existing data sources was conducted prior to 

field work. A volume of baseline data has been prepared for the BNCC mine lease area and the proposed 

power plant site. Intensive biological investigations, including species-specific surveys for federally 

listed and special status flora and fauna were conducted during between the 2004 and 2006 field seasons 

by biologists and botanists from Ecosphere. In addition to surveys completed specific to the proposed 

action, biologists and botanists from Ecosphere have conducted numerous biological and botanical 

investigations within and adjacent to the boundaries of Navajo Mine, the Four Corners Generating 

Station, Shiprock and Nenanhazad Chapters, and along the eastern end of the Navajo Transmission 

Project, all areas within or immediately adjacent to the analysis area. Surveys were conducted according 

to USFWS survey protocols or for those species for which no federal survey protocol has been 

established, by using other commonly accepted survey methods. The USFWS conducts annual 

monitoring of fish species in support of the San Juan Recovery Implementation Plan. As adequate 
Biological Assessment of the Desert Rock Energy Project, April 2007 14

baseline data exists for the fish species, species-specific surveys were not conducted for these aquatic 

species for the Desert Rock Energy Project. 

5.1 ESA Listed Species With Potential to Occur in the Analysis Area 

There are 9 threatened (T) and endangered (E) species with potential to occur in San Juan County. The 

list includes one mammal, three birds, two fish, and three plants. The federally threatened and 

endangered species considered in this BA include: 

• Black-footed ferret (Mustela nigripes), E 

• Bald eagle (Haliaeetus leucocephalus), T 

• Mexican spotted owl (Strix occidentalis lucida), T 

• Southwestern willow flycatcher (Empidonax traillii extimus), E 

• Colorado pikeminnow (Ptychocheilus lucius), E 

• Razorback sucker (Xyrauchen texanus), E 

• Knowlton’s cactus (Pediocactus knowltonii), E 

• Mancos milkvetch (Astragalus humillimus), E 

• Mesa Verde cactus (Sclerocactus mesaeverdae), T 

There is one candidate species listed by USFWS with potential to occur in the analysis area. Potential 

project effects to the yellow-billed cuckoo (Coccyzus americanus occidentalis) are also considered in this 

BA.

5.2 ESA Listed Species Eliminated From Detailed Evaluation 

Due to the absence of suitable habitat or listed species within the analysis area, 3 of the 10 federally listed 

species are eliminated from detailed evaluation in this BA. Species eliminated from further analysis are 

the black-footed ferret, Mexican spotted owl, and Knowlton’s cactus. Table 5-1 provides the reasoning 

for eliminating each species from further evaluation. 

Table 5-1. Species listed by the USFWS under the authority of the ESA with Potential to 

Occur in San Juan County, New Mexico, but Eliminated from Further Analysis. 

SPECIES STATUS HABITAT ASSOCIATIONS POTENTIAL TO OCCUR IN 

THE ANALYSIS AREA 

MAMMALS 

Black-footed ferret 

(Mustela nigripes) E 

Open grasslands with year-round 

prairie dog colonies. The Navajo 

Nation Department of Fish and 

Wildlife (NNDFW) defines 

potential habitat as occupied p-dog 

colonies 80 hectares or larger. 

The analysis area does not contain 

any prairie dog colonies that 

exceed 80 hectares. 

BIRDS

Mexican spotted owl 

(Strix occidentalis 

lucida) 

T 

Nests in caves, cliffs, or trees in 

steep-walled canyons of mixed 

conifer forests. 

There is no mixed conifer forest, 

or steep-walled canyon habitat 

types in the analysis area. 
Biological Assessment of the Desert Rock Energy Project, April 2007 15

SPECIES STATUS HABITAT ASSOCIATIONS POTENTIAL TO OCCUR IN 

THE ANALYSIS AREA 

PLANTS 

Knowlton’s cactus 

(Pediocactus 

knowltonii) 

E 

Alluvial deposits that form rolling, 

gravelly hills in pinyon-juniper and 

sagebrush communities (6,200-

6,400 ft.). 

The analysisarea does not contain 

any gravelly hills in pinyonjuniper and sagebrush 

communities. Further, the project 

area is more than 80 miles from 

the only known population of 

Knowlton’s cactus. 

Source: USFWS Southwest Region Ecological Services Endangered Species Lists 

(http://ifw2es.fws.gov/EndangeredSpecies/lists/default.cfm; accessed February 2006). 

FWS ESA: Federal Endangered Species Act of 1973; 12-28-73, P.L. 93-205 87 Stat. 884, as amended. Administered by U.S. 

Fish and Wildlife Service, Department of Interior. List is published as 50 CFR 17.11 and 17.12. 

E = ENDANGERED: "... any species which is in danger of extinction throughout all or a significant portion of its range ...". A 

final rule has been published in the Federal Register. 

T = THREATENED: "... any species which is likely to become an endangered species within the foreseeable future throughout 

5.3 Designated Critical Habitat in the Analysis Area 

Designated critical habitat for the Colorado pikeminnow and razorback sucker occur within the San Juan 

River through the northern portion of the analysis area (Federal Register 1994). The project area does not 

contain critical habitat for any other ESA listed species. 

In March 1994, the Department of the Interior designated 1,980 miles of the Colorado River as "critical 

habitat" for Colorado pikeminnow and razorback sucker. These fish have similar habitat requirements and 

historically lived in the same rivers. In Colorado and Utah, critical habitat covers the Colorado River from 

Rifle, Colorado, to Lake Powell; the Gunnison River from Delta, Colorado, to Grand Junction; the Yampa 

River from Craig, Colorado, to the Green River; the White River from Rio Blanco Dam to the Green 

River; and the Green River from Dinosaur National Monument to Lake Powell. The critical habitat also 

includes a 100-year flood plain of the Gunnison River from its confluence with the Colorado River and 

upstream to the confluence with the Uncompahgre River. There are no proposed critical habitats in 

Wyoming or California. Legal coordinates of critical habitats for these species within the project area are 

described below. 

5.3.1 Colorado Pikeminnow 

Critical habitat for the Colorado pikeminnow includes the San Juan River and its 100-year flood plain 

from the State Route 371 Bridge in Township 29 North, Range 13 W, Section 17 (New Mexico Meridian) 

to Neskahai Canyon in the San Juan arm of Lake Powell in Township 41 South, Range 11 East, Section. 

26 (Salt Lake Meridian) up to the full pool elevation. In the project area, critical habitat for the Colorado 

pikeminnow is limited to the San Juan River from State Route (SR) 371 bridge (near Farmington, New 

Mexico) downstream to Neskahai Canyon in the San Juan arm of Lake Powell. 

5.3.2 Razorback Sucker 

Critical habitat for the razorback sucker includes the San Juan River and its 100-year flood plain from the 

Hogback Diversion in Township 29 North, Range 16 West, Section 9 (New Mexico Principal Meridian) 

to the full pool elevation at the mouth of Neskahai Canyon on the San Juan arm of Lake Powell in 
Biological Assessment of the Desert Rock Energy Project, April 2007 16

Township 41 South, Range 11 East, Section 26 (Salt Lake Meridian). Thus, the entire stretch of the San 

Juan River that crosses the project area is included in the critical habitat designation. 

6.0 Effects of the Proposed Action 

This section addresses the predicted or anticipated impacts on biological resources that are attributable to 

the proposed project, including the following sources: air quality, water quality, noise pollution, 

infrastructure related disturbance and human related disturbance. Information used to compile this 

section was gathered from the DEIS (URS 2007) and the project Risk Analysis for Toxics prepared by 

URS, as well as from data collected during field based evaluations and a literature review. The complete 

Risk Analysis for Toxics prepared for the Desert Rock Energy Project is contained with the DEIS, 

however the ecological risk assessment portion of the document is included in Appendix C. 

6.1 Evaluating Risk of Particulates to Plants, Soil Invertebrates and Wildlife 

Potential risks to ecological receptors (plants, soil invertebrates and wildlife) from the proposed plant’s 

chemical emissions were evaluated in combination with the concentrations of these chemicals already 

present in the environment, to the extent that existing conditions are known. The risk analysis generally 

followed risk assessment procedures developed by USEPA (1992 and 1998). The ecological risk 

evaluation prepared by URS is provided in Appendix C. The ecological assessment includes a screening

process where chemicals of potential ecological concern (COPECs) are selected and the subsequent riskbased assessment where site-specific risks and impacts are evaluated. 

Soil and vegetation samples were collected for chemical analysis of metals. Results were used as baseline 

concentrations in the risk-based assessment of impacts from airborne dispersal and deposition of 

particulates on soils and plants, and ultimately, on wildlife and humans. By collecting soil and vegetation 

metals data, site-specific uptake rates could be generated for use in estimating metals concentrations in 

plants after 50 years of operation. Details of the soil and vegetation sampling are provided in Appendix 

C. 

Twenty-four sampling locations within a 25-km radius air impact area (1,962 km2

) were sampled in June 

2006. At each location, samples of four media were collected for metals analysis: 

• Surface soil (0-2 cm) 

• Subsurface soil (2 cm down to the root zone [typically less than 40 cm]) 

• Vegetation leaves and stems 

• Vegetation roots or tubers 

ENSR modeled particulate (chemical emissions) deposition rates (wet, dry, and total) of the proposed 

Desert Rock power plant boilers using CALPUF and three years of meteorological data (2001-2003) 

(URS 2007). Wet deposition dominated the total deposition rates in all three years. For the risk based 

assessment, the area of wet deposition was sampled along with areas in the two down-wind/dry 

deposition directions. 

The plant species collected (one species per location) included the following: 

• Shadscale (Atriplex confertifolia) 

• Alkali saccaton (Sporobolus airoides) 

• New Mexico saltbush (Atriplex obovata) 

• Four-winged saltbush (Atriplex canescens) 

• Torrey’s ephedra (Ephedra torreyana) 

• Broom snake weed (Gutierrezia sarothrae) 
Biological Assessment of the Desert Rock Energy Project, April 2007 17

Each soil and plant sample was analyzed for the eight naturally occurring Resource Conservation and 

Recovery Act (RCRA) metals most likely to represent a health concern for either human or ecological 

receptors – arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), mercury (Hg), selenium (Se). Six of 

these metals (excluding barium and silver) are also listed as hazardous air pollutants (HAPs) that could be 

deposited on soil and plants in the air impact area. 

The soil summaries are based on the higher of surface or subsurface soil concentrations at each sampling 

location. Concentrations of metals in surface soils were found to not be substantially different from area 

to area. A similar pattern of metals concentrations among areas was seen in the subsurface soils. 

Differences among metal uptake rates in the various plants (subsurface soils to upper plant parts) and in 

the exposure areas also were examined (URS 2007). 

 

Because different plants were sampled in the three exposure areas, uptake rates varied among areas and 

among plants, and uptake rates were different for each metal, the overall combined 90th percentile uptake 

rates for each plant part (upper or lower) and each metal are used in the subsequent analyses. All uptake 

rates are based on dry-weight metals concentrations. 

6.1.1 Screening 

The ecological screening phase is a conservative evaluation used to select COPECs (chemicals of 

potential ecological concern). The goal of the screening process is not to provide an indication of 

potential for risk, but rather to identify chemicals that may warrant further evaluation using more detailed 

procedures. Sources for soil (terrestrial) ecological screening levels (ESLs) for metals include: 1) 

USEPA’s Ecological Soil Screening Levels (2005a), and 2) the Los Alamos National Laboratory (LANL) 

Ecorisk Database Release 2.2 (2005). 

Two metals (mercury and selenium) have estimated 50-year concentrations in soil that exceed ESLs and 

are therefore considered COPECs. Estimated concentrations of the COPECs, which include deposition 

plus baseline (existing concentrations), in both the 0-2 and 0-10 cm soil depth profiles exceed the 

respective ESLs. The higher of these two soil estimates for each metal are used as exposure point 

concentrations (EPCs) as these two metals are carried forward into the risk-based assessment. The 

mercury EPC is 2.41E-02, and the selenium EPC is 3.20E+00. 

The estimated concentration of bis(2-ethylhexyl)phthalate in soil (2.5E-02) after 50 years of plant 

operation also exceeds a conservative ESL from LANL (2005) for birds (2.0E-02). It does not exceed the 

ESL for mammals (5.9E-01). Bis(2-ethylhexyl)phthalate is not carried forward into the risk-based 

assessment because the modeled soil concentration does not take into account the several conservative 

factors that act preferentially to reduce organic compound concentrations. 

6.1.2 Risk-based Assessment 

The risk-based assessment includes six steps: Problem Formulation, Exposure Analysis, Ecological 

Effects of Chemicals, Risk Estimates, Risk Descriptions, and Uncertainty. 

Problem Formulation 

Three key aspects of the Problem Formulation are identifying assessment endpoints, and associated 

testable hypotheses and measurement endpoints (measures of effect) to determine whether a potential risk 

to the assessment endpoint exists. 

Assessment endpoints are explicit expressions of the actual ecological value that is to be protected, 

typically this defined by an ecological entity and its attributes. Two elements are required to form an 
Biological Assessment of the Desert Rock Energy Project, April 2007 18

assessment endpoint. The first is the identification of the specific valued ecological entity. This can be a 

species (e.g., red-tailed hawk), a group of species (e.g., avian herbivores), a community (e.g., soil 

invertebrates), an ecosystem function or characteristic, or a specific habitat. The second is the 

characteristics or attributes about the entity of concern that is important to protect and potentially is at 

risk. Therefore, it is necessary to define what is important for avian herbivores (e.g., survival growth and 

reproduction) or a plant community (e.g., viability and function. Together “viability and function of the 

plant community” form the assessment endpoint. 

In this risk-based assessment, testable hypotheses are specific risk questions that are based on the 

ecological values to be protected (e.g., assessment endpoints such as avian herbivores) and what 

responses those ecological values may show when they are exposed to a stressor. In this evaluation the 

stressors are the chemicals of potential ecological concern (COPECs) mercury and selenium. 

Measurement endpoints (measures of effect) are measurable or quantifiable changes in an attribute of an 

assessment endpoint in response to a stressor to which it is exposed. 

A summary of assessment endpoints (in bold type) and associated testable hypotheses and measurement 

endpoints is presented below. The testable hypotheses are based on concentrations on estimated COPECs 

concentrations after 50 years of Desert Rock power plant operation. All of the wildlife species listed as 

receptors (ecological entity exposed to the stressor) are known to occur in the Desert Rock site area. 

The general strategies used to evaluate ecological risks in the risk-based assessment are: 1) comparisons 

of the exposure concentration in soil with a toxicity reference value (TRV) for plants or soil invertebrates, 

or 2) comparisons of the dietary dose for a wildlife receptor with a dietary TRV. In the evaluation, TRVs 

are selected based on both no effect (e.g., no adverse observed effect level [NOAEL]), and low effect 

(e.g., lowest observed adverse effect level [LOAEL]) concentrations or doses to provide a range in the 

potential for effects. 

Viability and Function of the Plant Community 

Testable Hypothesis 1 – Are the concentrations of COPECs in soils sufficient to impair the viability and 

function of the plant community? 

Measurement Endpoint 1 –Conservative exposure concentrations of COPECs in soil are compared with 

TRV concentrations available for screening and risk assessment. 

Viability and Function of the Soil Invertebrate Community 

Testable Hypothesis 2 – Are the concentrations of COPECs in soils sufficient to impair the viability and 

function of the soil invertebrate community? 

Measurement Endpoint 2 – Conservative exposure concentrations of COPECs in soil are compared with 

invertebrate TRV concentrations available for screening and risk assessment. 

Survival, Growth, and Reproduction of Birds and Mammals (Herbivores) 

Testable Hypothesis 3 – Are the concentrations of COPECs in the upper portions of plants sufficient to 

impair the survival, growth, and reproduction of birds and mammals described as herbivores? 

Measurement Endpoint 3 – To evaluate this assessment endpoint in the evaluation, the dietary dose that a 

wildlife receptor receives from plants and soils is compared with TRVs from the literature. TRVs for each 

soil COPEC representing no observed adverse effect level (NOAEL) and lowest observed adverse effect 

level (LOAEL) doses are selected or developed to provide a range in potential effects in the evaluation. 
Biological Assessment of the Desert Rock Energy Project, April 2007 19

The herbivorous receptors used in the assessment are the horned lark (Eremophila alpestris) and the 

black-tailed jackrabbit (Lepus californicus). Both receptors are assumed to ingest upper portions of plants. 

Survival, Growth, and Reproduction of Birds and Mammals (Insectivores) 

Testable Hypothesis 4 – Are the concentrations of COPECs in soils sufficient to impair the survival, 

growth, and reproduction of birds and mammals described as insectivores (a subset of carnivores)? 

Measurement Endpoint 4 – To evaluate this assessment endpoint in the evaluation, the dietary dose that a 

receptor receives from soils and soil invertebrates is compared with TRVs from the literature. TRVs for 

each soil COPEC representing NOAEL and LOAEL doses are selected from the literature to provide a 

range in potential effects. The insectivorous receptors used in the assessment are the western meadowlark 

(Sturnella neglecta) and the deer mouse (Peromyscus maniculatus). It is assumed that the deer mouse eats 

primarily insects, although it also reportedly eats seeds and some green vegetation (USEPA 1993). 

Survival, Growth, and Reproduction of Birds and Mammals (Carnivores) 

Testable Hypothesis 5 – Are the concentrations of COPECs in soils sufficient to impair the survival, 

growth, and reproduction of higher tropic level carnivorous birds and mammals? 

Measurement Endpoint 5 – To evaluate this assessment endpoint in the evaluation, the dietary dose that a 

receptor receives from soil and from small mammalian prey is compared with TRVs from the literature. 

For the assessment, TRVs for each COPEC representing a NOAEL and LOAEL are selected from the 

literature. The carnivorous receptors used in the assessment are the red-tailed hawk (Buteo jamaicensis) 

and the kit fox (Vulpes macrotis). 

Exposure Analysis 

Exposure of receptors can be through direct contact (i.e., direct exposure) or through the ingestion 

pathway. For both types of exposure, the EPC of each COPEC must be estimated. Metals concentrations 

from the 0-2 cm soil depth assumed mixing depth profile are used as EPCs. The principal release 

mechanism of emissions from the Desert Rock power plant is Deposition – Wet, Dry, and in the direction 

of the Prevailing Winds. Exposure pathways expected to be complete (and evaluated) are shown with a 

“C” under each receptor. Plants and soil invertebrates are in direct contact with COPECs in soils. 

Ingestion-pathway exposures of the vertebrate receptors are estimated as average daily doses (ADDs) 

using the approach outlined in USEPA (1993) as follows: 

For food and soil: 

ADD = [(IRf*Cf) + (IRs*Cs)] * BA*AUF/bw 

where: 

IRf = Ingestion rate of food (kg/day) 

IRs = Ingestion rate (incidental) of soil/sediment (kg/day) 

Cf = Concentration of COPEC in food (mg/kg) 

Cs = Concentration of COPEC in soil (mg/kg) 

BA = Bioavailability of COPEC in soil and food (assumed to be 1.0) 

AUF = Area use factor (assumed to be 1.0) 

bw = Body weight of the receptor (kg) 
Biological Assessment of the Desert Rock Energy Project, April 2007 20

Concentrations of COPECs in plants or prey organisms ingested by terrestrial wildlife in 2056 (following 

50 years of plant operation) are estimated by the application of a bioconcentration factor (BCF) or 

bioaccumulation factor (BAF) to the calculated soil EPC for the COPEC: 

Cf = BCF*Cs or 

Cf = BAF*Cs 

As described above, BCFs for plants and the six metals of interest were calculated from site-specific data 

for subsurface soil and plant upper portions (leaves and stems). These site-specific BCFs were then 

applied to 50-year soil column (0-10 cm) concentrations to estimate metals concentrations in plants after 

50 years when projected soil concentrations reach anticipated maximums due to aerial deposition of 

particulates. BCFs from the literature are used with 50-year soil (0-10 cm) concentrations to estimate 

metals concentrations in soil invertebrates. BAFs are used with 50-year surface soil (0-2 cm) 

concentrations to estimate concentrations in small birds or mammals (prey organisms). 

Ecological Impacts of Contaminants 

The effects of contaminants on ecological receptors can be based on direct comparisons of toxicological 

reference values (TRVs) with measured concentrations in the abiotic exposure media expressed as mg/kg 

or mg/L, or effects can be based on comparisons of the reference doses with estimated doses that a 

wildlife receptor receives from the environment. Doses are expressed as mg/kg-body weight/day. 

To evaluate potential risks to plants and soil invertebrates, comparisons of EPCs were made with 10 x 

ESLs, used to represent lowest observed effect concentrations (LOECs). 

In accordance with assessment endpoints involving survival, reproduction, development, and/or growth 

for the terrestrial-feeding wildlife, appropriate dietary toxicological endpoints (i.e., doses) for COPECs 

were reviewed for application in the evaluation. Both LOAEL and NOAEL values are applied in the 

evaluation to provide a range of risk assessment results for wildlife. The primary source for all ingestion 

pathway TRVs is the LANL (2005). 

6.1.3 Risk Estimates 

Risk estimates, expressed in terms of hazard quotients (HQs), based on both NOAELs and LOAELs or 

equivalent benchmarks to provide a range of predicted outcomes, and were calculated for each 

appropriate receptor group for the site. 

HQ = EPC or Dose / TRV 

HQs are interpreted as follows: 

• HQNOAEL <1 suggests no risk. 

• HQNOAEL >1 but HQLOAEL <1 suggests potential risks, and the uncertainty associated with this 

conclusion must be evaluated further. 

• HQLOAEL >1 suggests potential risks. 

Although the HQ is not a definitive measure, it can be used to estimate the potential level at which the 

measured or predicted exposure (EPC or Dose) relates to known levels at which adverse effects have been 

observed in laboratory toxicological studies or found not to be statistically significant (the LOAEL and 

NOAEL, respectively). Nevertheless, these HQs contribute to the “line-of-evidence” for interpreting the 
Biological Assessment of the Desert Rock Energy Project, April 2007 21

potential for ecological risks. However, the LOAEL dose is the appropriate TRV for evaluating risk at the 

population level for common species that serve as wildlife receptors. 

6.1.4 Risk Estimate Results 

Results of the risk estimation process in terms of HQs are provided in the following tables. These results 

are discussed further in the vegetation and wildlife sections below and in Ecological Risk Assessment in 

Appendix C. 

Table 6-1 Risk Estimate Results in Hazard Quotients (HQs) for Plants and Soil 

Invertebrates. Desert Rock Energy Project. 

Analyte 

Concentration in 

Soil After 50 Years 

of Deposition 

(mg/kg) 

Plant 

Surrogate 

LOEC 

(mg/kg) 

Plant 

HQ 

Soil 

Invertebrate 

Surrogate 

LOEC (mg/kg) 

Soil 

Invertebrate 

HQ 

Surface Soil (0-2 

cm) 

Mercury 2.41E-02 340 7.09E-05 0.5 4.82E-02 

Selenium 3.20E+00 1 3.20E+00 77 4.16E-02 

Soil Column (0-10 

cm) 

Mercury 2.15E-02 340 6.32E-05 0.5 4.30E-02 

Selenium 9.98E-01 1 9.98E-01 77 1.30E-02 

Source: URS 2007 

Hazard Quotients exceeding 1.0 are shown in bold. 

cm = centimeters 

ESL = Ecological Screening Level. See LANL (2005) in Table 4.1-1 

HQ = hazard quotient; concentration in soil/ESL 

LANL = Los Alamos National Laboratory 

LOEC = lowest observed effect concentration; estimated at 10 X ESL 

mg/kg = milligrams per kilogram 

SSL = Soil Screening Level 

Table 6-2 Risk Estimate Results in Hazard Quotients (HQs) for Plants and Soil 

Invertebrates. Desert Rock Energy Project. 

 Avian Herbivore Avian Carnivore Avian Insectivore 

 Horned Lark Red-tailed Hawk Western Meadowlark 

COPECs NOAEL LOAEL NOAEL LOAEL NOAEL LOAEL 

 

Mercury 2.0E+00 2.0E-01 2.7E-02 2.7E-03 1.0E-01 1.0E-02 

Selenium 2.8E+00 8.3E-01 7.1E-03 2.1E-03 6.0E-02 1.8E-02 

 Mammalian Herbivore Mammalian Insectivore Mammalian Carnivore 

 Black-tailed Jackrabbit Deer Mouse Kit Fox 

COPECs NOAEL LOAEL NOAEL LOAEL NOAEL LOAEL 

 

Mercury 5.5E-03 5.5E-04 7.0E-03 7.0E-04 3.1E-04 3.1E-05 

Selenium 1.3E+00 8.0E-01 6.0E-01 3.6E-01 3.9E-02 2.4E-02 

Source: URS 2007 

Hazard Quotients exceeding 1.0 are shown in bold. 

COPECs = chemicals of potential ecological concern 

LOAEL = lowest observed adverse effects level 

NOAEL = no observed adverse effects level 
Biological Assessment of the Desert Rock Energy Project, April 2007 22

6.2 Air Quality Effects 

Estimated emissions of chemical air pollutants and toxicants associated with the Desert Rock Energy 

Project were extracted from the air quality permit application prepared by ENSR for Desert Rock Energy, 

LLC and submitted to the U.S. Environmental Protection Agency (EPA) Region 9. In addition, ENSR 

performed dispersion modeling to evaluate air quality impacts of the power plant on local and regional air 

quality, including the deposition of particulate matter, sulfates, nitrates, dioxin and six metals; arsenic, 

cadmium, chromium, lead, mercury, and selenium. Based on results of these studies, the primary air 

pollutants associated with the Desert Rock Energy Project are expected to be fugitive dust associated with 

construction and mining activities, as well as emissions of chemical air pollutants and toxics associated 

with operation of the power plant and exhaust emissions from vehicles and other equipment (URS 2007). 

6.2.1 Fugitive Dust 

Earthmoving activity associated with construction projects typically cause emissions of particulate matter, 

in the form of fugitive dust. 

Power Plant Site. URS conservatively assumed that up to 120 acres of ground surface would undergo 

active earthmoving activity at any one time on the power plant site. Maximum controlled PM10 emissions 

from plant site construction are estimated to be 13.2 tons/month. Based on a 36-month construction 

schedule, it is estimated that a maximum of 475.20 tons of PM10 will be emitted during plant site 

construction. 

Water Well Field and Water Supply Pipeline. URS conservatively assumed that twenty production wells 

would be installed within the well fields for either sub-alternative well field area B (proposed) or A. In 

addition, based on the anticipated geospatial arrangement of the wells, up to fifteen miles of well field 

interconnection piping trenches and fifteen miles of two-track roadways to access the work areas within 

the well field may be required. A total of 109.3 acres of work area was estimated for the well field 

associated with each sub-alternative. Maximum controlled PM10 emissions from the well field under 

either preferred sub-alternative B or sub-alternative A are estimated to be 45.9 tons/month. Based on a 

six-month construction schedule, it is estimated that a maximum of 275.4 tons of PM10 would be emitted 

during construction of the well field under either sub-alternative. Under sub-alternative A, an additional 

twelve miles of water supply pipeline would be constructed along the utility corridor to bring the water to 

the plant site. Maximum controlled PM10 emissions from installation of the water supply pipeline, within 

the utility corridor under sub-alternative A are estimated to be 62.9 tons/month. Based on a twelve-month 

construction schedule, it is estimated that an additional 377.4 tons of PM10 will be emitted during 

installation of the water supply pipeline under sub-alternative A. 

Transmission Lines. Based on a nine-month construction schedule, it is estimated that a maximum of 

115.7 tons of PM10 would be emitted during construction of Segments A, C and D. An alternate 

transmission line route would replace of Segment A with a longer Segment B. Segment B is 11.1 miles 

long. Maximum controlled PM10 emissions from construction of Segment B are estimated to be 7.6 

tons/month. Based on a nine-month construction schedule, it is estimated that a maximum of 172.8 tons 

of PM10 will be emitted during construction of Segments B, C and D (a net increase of 57.1 tons over the 

proposed transmission line). 

Access Roads. Maximum controlled PM10 emissions from construction of the road are estimated to be 8.4 

tons/month. Based on a 12-month construction schedule, it is estimated that a maximum of 100.8 tons of 

PM10 would be emitted during construction of the plant access road. 
Biological Assessment of the Desert Rock Energy Project, April 2007 23

For the proposed alternatives, the total maximum controlled PM10 emissions from construction of the 

plant site, well fields, transmission lines and access road are estimated to be 147.7 tons/month. Since 

these emissions are generated by earthmoving activity and occur at ground level, it is unlikely that the 

PM10 would be transported more than one or two kilometers, except on unusually windy days (see 

Mitigation section for dust control measures during periods of high wind). In addition, the PM10

emissions will be spatially distributed over a large area and spread out over construction schedules 

ranging from 6 to 36 months. Furthermore, the locations of active work areas will be transient, with work 

activities typically moving to a new location every few days. Finally, the PM10 emissions from 

earthmoving activity will be temporary, ceasing as each phase of the project is completed. 

Apart from screening out sunlight, PM 10 in the form of fugitive dust that is deposited on leaves of plants 

blocks their conductance of CO2, thus reducing photosynthetic capacity. Impacts may include low 

viability of annual species or reduced growth rates during periods when fugitive dust is particularly high. 

Fugitive dust has the potential to impair respiratory functions of wildlife; however, there are few 

published studies that address the short or long-term implications of dust pollution on wildlife health. At 

high levels, fugitive dust can impair visibility, limiting the ability of predators to spot prey and, 

conversely, reduce the ability of prey to evade predators. 

In the project area, the impact of dust pollution on vegetation and wildlife is expected to be of localized 

importance near construction areas. Likewise, because intensive construction is only expected to occur 

for less than 36 months, dust pollution that results from construction activities is expected to have only 

short-term impacts on vegetation and wildlife and would be limited to the time of construction 

disturbance. Impacts from fugitive dust resulting from mine operations would be low, localized and long 

term. 

6.2.2 Emissions 

During construction, gasoline and diesel fueled vehicles and equipment will generate gaseous and 

particulate exhaust emissions, including volatile organic compounds (VOCs), carbon monoxide (CO), 

nitrogen oxides (NOx) and PM10. In the DEIS, annual emissions for all diesel-fueled vehicles and 

equipment were calculated based on average engine horsepower for each type of vehicles and equipment, 

and an operating schedule of 10 hours/day, 6 days/week and 52 weeks/year. Annual emissions for 

gasoline-fueled pickup trucks and crew cabs were calculated based on a traveling distance of 10 miles/day 

during Power Plant construction, 25 miles/day during Access Road construction, and 50 miles/day during 

transmission line and water conveyance system construction, all with an operating schedule of 6 

days/week and 52 weeks/year (URS 2007). Maximum annual tailpipe emissions from plant employees 

commuting to the project site would be 13.5 tons VOC, 132.0 tons CO, 6.9 tons NOx, 2.7 tons PM10 and 

0.3 tons of SO2. These emissions would be mobile and distributed across a large rural area; therefore, the 

ambient air quality impacts would be considered negligible. 

In the project area, the impact of vehicle emissions on vegetation and wildlife is expected to be of 

localized importance near construction areas. Intensive construction is only expected to occur for less 

than 36 months, emissions from construction activities are expected to have only short-term impacts on 

vegetation and wildlife and would be limited to the time of construction disturbance. Impacts from 

vehicle emissions resulting from mine operations would be low, localized and long term. 

Criteria air pollutant emission rates were obtained from the Prevention of Significant Deterioration (PSD) 

permit application. Table 6-3 presents a summary of maximum potential-to-emit (PTE) criteria air 

pollutant emission rates from the proposed power plant. These emission rates are based on the 

conservative assumption that both generating units of the plant will operate for 8,760 hours each year, at 
Biological Assessment of the Desert Rock Energy Project, April 2007 24

full-load operation. Based on these PTE values, the proposed power plant will be a major source, as 

defined under federal New Source Review and Prevention of Significant Deterioration (NSR/PSD) 

regulations, codified at 40 CFR §51.166, for PM10, NOx, SO2, CO, Ozone (NOx and VOC emissions) and 

lead (URS 2007). 

Table 6-3. Summary of Maximum Potential Criteria Pollutant Emissions in Tons Per Year 

(typ) from Proposed Desert Rock Energy Project Power Plant (URS 2007) 

Pollutant 

PC Boilers 

(tpy) 

Auxiliary 

Boilers (tpy)

Emergency 

Generators 

(tpy) 

Fire 

Water 

Pumps 

(tpy) 

Material 

Handling 

(tpy) 

Storage 

Tanks (tpy)

Project 

PTE 

(tpy) 

CO 5,526 2.55 0.17 0.031 n/a n/a 5,529 

NOx 3,315 7.13 2.26 0.41 n/a n/a 3,325 

SO2 3,315 3.61 0.068 0.012 n/a n/a 3,319 

PM 553 1.02 0.083 0.015 22.3 n/a 576 

PM10 1,105 1.68 0.077 0.014 18.4 n/a 1,125 

VOC 166 0.17 0.11 0.019 n/a 0.14 166 

Lead 0.1 0.00064 0.000012 0.0000022 n/a n/a 0.1 

Fluorides 13.3 neg neg neg n/a n/a 13.3 

H2SO4 221 0.062 0.002 0.0004 n/a n/a 221 

Mercury 0.057 0.00021 neg neg n/a n/a 0.057 

Hydrogen Sulfide neg neg neg neg n/a n/a neg 

Total Reduced 

Sulfur 

neg neg neg neg n/a n/a neg 

Reduced Sulfur 

Compounds 

neg neg neg neg n/a n/a neg 

SOURCE: ENSR/AECOM Desert Rock Updated Class I Modeling Report January 2006 In URS 2006 

n/a – not applicable, neg. – negligible 

The DEIS (2007) for the Desert Rock Energy Project specifies that approximately 7,000 tons of coal will 

be combusted in the power plant facility each year. This will result in the emission of several chemical 

pollutants and toxicants including volatile organic compounds (VOCs), carbon monoxide (CO), nitrogen 

oxide (NOx) and PM10, as well as sulphur dioxide (SO2). Table 6-3 displays the maximum predicted air 

quality impacts from the proposed action. The DEIS estimates that the Desert Rock Energy Project will 

result in generation of 166 tons/year of VOCs, which is an increase of 21.5% over existing emissions in 

the Four Corners Region. It is estimated that CO emissions will be approximately 5,529 tons/year, an 

increase of 46.5% over existing conditions. NOx emissions are estimated to be 3,325 tons/year, an 

increase of 2.3% over existing conditions. PM10 emissions associated with operation of the power plant 

facility are estimated to be 1,125 tons/year, an increase of 13.5% over existing conditions. SO2 emissions 

are expected to be approximately 3,319 tons/year, an increase of 2.8% over existing conditions. 

Maximum predicted air quality impacts from the proposed project are detailed in the DEIS; however, 

computer-based modeling analyses indicate that maximum predicted ambient concentrations of NOx

(annual), SO2 (annual), and CO (1 hr and 8 hr) will be below the significant impact levels for these 

pollutants within 1 km of the proposed power plant site (URS 2007). In contrast, maximum annual 

predicted ambient concentrations of PM10 (24 hr and annual) and SO2 (3 hr and 24 hr) will be above 

significant impact limits for these pollutants within 1 km of the power plant facility. The model predicted 

air concentrations of the criteria pollutants decrease with greater distance from the proposed site. This 

analysis indicates that the predicted plant emissions are not expected to increase air concentrations of any 

of the criteria pollutants to concentrations exceeding the National Ambient Air Quality Standards 

(NAAQS) criteria, at any location from the power plant fence line out. 
Biological Assessment of the Desert Rock Energy Project, April 2007 25

Six metals, two dioxins and monomethyl hydrazine were selected for human health and ecological risk 

assessment analysis. Using AP-42 emission factors for hazardous air pollutants (HAPs) from coal 

combustion and the maximum coal combustion rates for the proposed power plant, HAP emission rates 

were calculated. Table 6-4 summarizes the coal combustion emission factors and calculated maximum 

emission rates, in pound per hour (lb/hour) and grams per second (g/sec) for these nine air toxics. The 

emission rates in g/sec were used to extrapolate predicted ambient concentrations and deposition rates, 

based on ENSR’s modeling results for a hypothetical toxic emitted at 1 g/sec (URS 2007). 

Table 6-4. Estimated Emission Rates in Pounds per Ton (lb/ton) and Grams per Second 

(g/s) for Selected Air Toxics from the Proposed Desert Rock Energy Project Power Plant. 

(URS 2007) 

Emissions Contaminant 1 AP-42 Emission 

Factor (lb/ton) (lb/yr) (g/s) 

Arsenic 4.1E-04 9.06E-02 1.30E-06 

Cadmium and compounds 5.1E-05 1.13E-02 1.62E-07 

Chromium VI 7.9E-05 5.55E+02 7.98E-03 

Lead 4.2E-04 9.28E-02 1.34E-06 

Mercury (elemental) 8.3E-05 1.83E-02 2.64E-07 

Selenium 1.3E-03 9.13E+03 1.31E-01 

2,3,7,8-TCDD (dioxin) 1.43E-11 3.16E-09 4.55E-14 

Total PCDD (dioxins) 6.66E-09 1.47E-06 2.12E-11 

TCDD = Tetrachlorodibenzo-P-Dioxin 

PCDD = Polychlorinated Dibenzo-P-Dioxins 

1

 From AP-42 for External Combustion Sources - Bituminous and Sub-bituminous Coal Combustion 9/98 (Emission Factors for 

controlled coal combustion) – Tables 1.1-18 (Trace Metals) and 1.1-12 (Dioxins) 

Chemical air pollution is often manifested in two general forms: phytochemical smog and acid rain, both 

of which can significantly impact vegetation. Photochemical smog is the product of chemical reactions 

driven by sunlight and involving NOx of urban and industrial origin and VOCs from either vegetation 

(biogenic hydrocarbons) or human activities (anthropogenic hydrocarbons). Ozone (O3) and 

peroxyacetylnitrate (PAN) produced in these complex reactions can become injurious to plants and other 

life forms, depending on concentration and duration of exposure. Generally, concentrations of SO2 and 

NOx in air that exceed 0.5 mL L–1 are known to inhibit plant growth (Zeiger et al. 2002). Plants are 

capable of a number of innate enzymatic processes that effectively detoxify chemical pollutants. 

However, when the concentration of chemical pollutants in plant tissue exceeds their innate detoxification 

mechanisms, processes including photosynthesis, water regulation and respiration are impaired, reducing 

growth and development (Brace et al. 1999). In addition, accumulation of chemical pollutants in plant 

tissue can result in harmful genetic mutations, which can greatly reduce the fitness of the organism and its 

offspring (Zeiger et al. 2002). 

The concentrations of chemical air pollutants that plants in the project area will be exposed are expected 

to be variable and depend on location, wind direction, rainfall, and sunlight. The response of plants to 

chemical pollutants are also expected to be affected by other ambient conditions, such as light, humidity, 

temperature, and the supply of water and minerals. In general, chemical pollution that interferes with the 

ability of plants to photosynthesize may be indicated by changes in the physical appearance. For 

example, damaged caused by SO2 is first noticeable on leaves of plants; leaves in mid-growth are the 

most vulnerable, whereas older and younger leaves are more resistant (Zeiger et al. 2002). Alternatively, 

O3 is often responsible for oxidative damage to cell membranes, limiting photosynthetic capacity, which 

can result in reduced growth and may increase the severity and susceptibility of plants to fungal diseases 

(Zeiger et al. 2002). Therefore, chemical air pollution has the potential to limit and/or reduce growth of 
Biological Assessment of the Desert Rock Energy Project, April 2007 26

vegetation. Likewise, chemical air pollution may increase susceptibility of plants to fungal disease, as 

well as infection with parasitic, viral and bacterial pathogens (Curtis 1996). 

Wildlife can be exposed to air pollutants via inhalation of gases or small particles, consumption of 

particles in food or water, and/or via absorption of gasses through the skin. In general, only soft-bodied 

invertebrates or amphibians are affected by the absorption of air pollutants. An individual's response to a 

pollutant varies greatly and depends on the type of pollutant involved, the duration and time of exposure, 

and the amount taken up by the animal (USEPA 2006). The individual's age, sex, health, and reproductive 

condition also play a role in its response (USEPA 2006). 

Impacts of chemical pollution, including phytochemical smog and acid rain, on wildlife have the potential 

to be more widespread than that caused by fugitive dust, and has potential to impact wildlife further from 

the pollution source. Similar to atmospheric dust, compounds including O3

, SO2 and NO2 have particularly 

negative impacts on the respiratory systems of animals. Compared to other groups of animals, birds may 

be most susceptible to illness or injury related to airborne chemical pollutants, due to their relatively 

higher respiratory rates (Kimball 2006). In addition to causing respiratory problems, chemical pollutants 

may accumulate in the tissues of both plants and wildlife, which can lead to tissue damage, genetic 

mutations and other negative impacts. The accumulation of chemical pollutants in the tissues of wildlife 

can also have additive impacts among successively higher trophic levels, as compounds that accumulate 

in vegetation are consumed by herbivores, which are in turn consumed by predators. This tendency for 

pollutants to reach progressively higher concentrations among higher levels in food webs is referred to as 

“biomagnification” (Kimball 2006). 

 

The concentrations of chemical air pollutants that wildlife in the project area will be exposed are expected 

to be variable and depend on location, wind direction and rainfall. Chemical pollution that results in tissue 

damage or mutation may be indicated by reductions in reproductive success, reduced longevity or death 

among individuals or cohorts of individuals in the project area and vicinity. In addition, changes in the 

physical appearance and/or behavior of wildlife may also be an indicator of the negative impacts of 

chemical air pollution. 

Potential risks to ecological receptors (soil invertebrates, vegetation and wildlife) from the proposed 

plant’s chemical emissions were evaluated in combination with the concentrations of these chemicals 

already present in the environment, to the extent that existing conditions are known. The risk analysis 

followed risk assessment procedures developed by USEPA. The ecological risk assessment includes a 

screening process where chemicals of potential ecological concern (COPECs) are selected and the 

subsequent risk-based assessment where site-specific risks and impacts are evaluated. A more detailed 

discussion of the ecological risk assessment is provided above in Section 5.1. Toxicity Reference Values 

(TRVs) for each soil COPEC representing NOAEL (no observed adverse effect level) and LOAEL 

(lowest observed adverse effect level) doses were selected or developed to provide a range in potential 

effects in the evaluation. The HQ (hazard quotient) tool as applied in the evaluation should not be 

construed as an accurate “measure” of risk, but rather as an “indication” of the potential for risk. 

Based on the results shown in these tables for the COPECs of mercury and selenium, maximum selenium 

concentrations in soil after 50 years present a possible risk (HQ = 3.2) to plants (Table 6-1). 

According to the ecological risk assessment prepared by URS, the calculated HQ for plants exposed to 

selenium is overly conservative due to conservative estimates of exposure and toxicological benchmarks. 

The selenium HQ of 3.2 is based on estimated surface soil (0-2 cm) concentrations; however, soil column 

(0-10 cm) concentrations in contact with plant root zones do not exceed the plant lowest observed effect 

concentrations (LOEC), and the LOAEL HQ is lower than 1.0. Also, the ESL (ecological screening 
Biological Assessment of the Desert Rock Energy Project, April 2007 27

level) for plants exposed to selenium (0.1 mg/kg) in LANL (2005) is overly conservative compared with 

screening benchmark from Efroymson et al. (1997). Therefore, the ecological risk assessment concludes 

that plants likely are not at risk from selenium deposited on the soils over the 50 years of power plant 

operation (URS 2007). 

According to the ecological risk assessment, based on LOAELs, none of the wildlife species, which 

represent herbivores, insectivores, and carnivores, are at risk from mercury or selenium deposited on soils 

(Table 6-2). HQs (LOAEL-based) for wildlife range from 3.1E-05 to 8.3E-01. The highest HQs are for 

the horned lark (avian herbivore) and the black-tailed jackrabbit (mammalian herbivore) exposed to 

selenium. The sensitivity of these two receptors to selenium (and to mercury) is seen in the NOAELbased HQs that are greater than 1.0. 

The calculated HQs for the horned lark and the black-tailed jackrabbit are, by design, very conservative, 

because the majority of uncertainties discussed in Appendix C contribute to an overestimate of exposure 

and risk (see Section 4.2.5 in Appendix C). The only HQs exceeding 1.0 are based on NOAEL dose 

TRVs (toxicity reference values). In the context of assessing risk to common species, LOAELs are the 

more appropriate TRVs because an impact at the population level is the threshold for significance. The 

HQs calculated using LOAEL TRVs are all lower than 1.0. The ecological risk assessment concludes 

that, the LOAEL-based HQs indicate unlikely potential risk for adverse effects to the survival, growth, or 

reproduction of terrestrial herbivorous birds or mammalian herbivores at the population level by the year 

2056 in areas of greatest deposition (URS 2007). 

Models predicting ozone concentrations were not evaluated because is not required under the PSD 

permitting procedures and the modeled ambient concentrations of ozone precursor compounds (NOx and 

VOC) were deemed insignificant (per the PSD criteria). 

6.3 Water Quality Effects 

6.3.1 Surface Water Quality 

Over a period of 7 years in the 1990s, aquatic plants, aquatic macroinvertebrates and fish tissues were 

sampled from the San Juan River by the U.S. Fish and Wildlife Service (USFWS 1999). Tissues were 

analyzed for 21 trace elements (metals) as well as hydrocarbons (primarily fossil fuels). Four trace 

elements (arsenic, copper, selenium and zinc) and hydrocarbons were identified as contaminants of 

concern in the San Juan River. The report tentatively concluded that concentrations of aluminum, iron, 

nickel, vanadium, chromium, lead, magnesium, boron and arsenic were from the ambient geochemical 

environment, rather than from point-sources of pollution. Sources of other pollutants were unknown or 

may have been from the ambient, geochemical environment and/or point sources of pollution. 

According to the report, both mercury and selenium are of concern to endangered fish species and to fish 

eating birds along the San Juan River. Twenty-two percent (22%) of fish samples, mostly from upstream 

reaches, exceeded the 0.1 μg/g wet weight of the mercury recommended threshold to protect sensitive 

species of fish eating birds. The document thus concluded that such birds could be at risk for mercury 

toxicity. Potential dietary items for Colorado pikeminnow (small fish, speckled dace, and red shiners) 

were found to exceed the selenium dietary criterion of 3.0μg/g. Invertebrates sampled from the San Juan 

River were found to exceed the dietary toxicity threshold for larval razorback suckers and one (1) plant 

sample, 45% of invertebrate samples and 76% of fish samples (including one razorback sucker) had 

selenium concentrations above thresholds of concern. Reproductive failure was expected to occur with a 

low-to-moderate occurrence in endangered fish species given selenium concentrations found in tissues 

and diets. 
Biological Assessment of the Desert Rock Energy Project, April 2007 28

In 2003, the USGS (Gray et. al 2004) conducted a study on Narraguinnep Reservoir, located in Cortez, 

Colorado to identify potential sources of mercury contamination in reservoir fish species. As there are no 

point sources of significant mercury contamination to this reservoir or its supply waters, the USGS 

evaluated potential historical mercury sources and deposition of mercury to Narraguinnep Reservoir by 

measuring mercury concentrations in sediment cores collected from the reservoir. The cores were dated 

by the 137Cs method and these dates were further refined by relating water supply basin hydrological 

records with core sedimentology. Rates of historical mercury flux were calculated (ng/cm2/a) based on 

the mercury concentrations in the cores, sediment bulk densities, and sedimentation rates. The flux of 

mercury found in Narraguinnep Reservoir increased by approximately a factor of 2 after about 1970. The 

three most likely sources of mercury to Narraguinnep Reservoir are surrounding bedrocks, upstream 

inactive gold-silver mines, and several coal-fired electric power plants in the Four Corners region. 

Patterns of mercury flux do not support dominant mercury derivation from surrounding bedrocks or 

upstream mining sources. There are fourteen (14) coal-fired power plants within 320 km of Narraguinnep 

Reservoir that produce over 80 x 106

 MWH of power and about 1640 kg-Hg/a are released through stack 

emissions, contributing significant mercury to the surrounding environment. Two of the largest power 

plants (Four Corners Power Plant and the San Juan Generating Station), located within 80 km of the 

reservoir, emit about 950 kg-Hg/a. Spatial and temporal patterns of mercury fluxes for sediment cores 

collected from Narraguinnep Reservoir suggest that the most likely source of mercury to this reservoir is 

from atmospheric emissions from the coal-fired electric power plants, the largest of which began 

operation in this region in the late-1960s and early 1970s. 

Air emissions from the proposed power plant, in particular small quantities of mercury and selenium, 

would be introduced into the San Juan River. Deposition of toxic chemicals in waterways from the 

proposed action would incrementally add to existing levels. Based on model output files, ENSR prepared 

a table of predicted deposition rates for air toxics emitted by the proposed Desert Rock power plant over a 

three year period (2001-2003) using meteorological conditions during those years. Predicted surface soil 

concentrations were highest if the 2003 meteorological conditions are constant for 50 years; however, the 

predicted 50-year concentration does not vary much between the three years. Table 6-5 presents the 

maximum predicted concentrations and deposition rates (wet, dry and total) of the selected air toxics, for 

the 2003 calendar year (URS 2007). 

Table 6-5. Modeled Concentrations and Deposition Rates for Selected Air Toxics (2003 

Meteorological Conditions) (URS 2007) 

Max Concentration 1 Max Wet Deposition 

Flux 2

Max Dry Deposition 

Flux 2 Total Deposition Max Rate 2

Contaminant 24-hour 

Avg. 

(micro 

g/m3) 

Annual 

Avg. (micro 

g/m3) 

24-hour 

Avg. 

(mg/m2 

day) 

Annual 

Avg. 

(mg/m2 yr)

24-hour 

Avg. 

(mg/m2 

day) 

Annual 

Avg. (mg/m2

yr) 

24-hour Avg. 

(mg/m2 day) 

Annual Avg. 

(mg/m2 yr) 

Arsenic 4.20E-03 1.41E-04 5.06E-02 1.68E-01 3.32E-08 4.08E-04 5.06E-05 1.68E-01 

Cadmium and 

compounds 5.22E-04 1.76E-05 6.29E-03 2.09E-02 4.13E-09 5.07E-05 6.29E-06 2.10E-02 

Chromium VI 8.09E-04 2.73E-05 9.75E-03 3.24E-02 6.40E-09 7.86E-05 9.75E-06 3.25E-02 

Lead 4.30E-03 1.45E-04 5.18E-02 1.72E-01 3.40E-08 4.18E-04 5.18E-05 1.73E-01 

Mercury 

(elemental) 8.50E-04 2.86E-05 1.02E-02 3.41E-02 6.72E-09 8.26E-05 1.02E-05 3.41E-02 

Selenium 1.33E-02 4.49E-04 1.60E-01 5.34E-01 1.05E-07 1.29E-03 1.60E-04 5.34E-01 

2,3,7,8-TCDD 

(dioxin) 1.46E-10 4.93E-12 1.76E-09 5.87E-09 1.16E-15 1.42E-11 1.76E-12 5.88E-09 

Total 

PCDD/PCDF 1.80E-08 6.07E-10 2.17E-07 7.22E-07 1.43E-13 1.75E-09 2.17E-10 7.23E-07 

Based on Modeled Concentrations and Deposition Rates for Hypothetical Pollutant Emitted at 1 μg/m3 provided by ENSR in URS 2007, PCDD = Polychlorinated Dibenzo-P-Dioxins; PCDF = 

Polychlorinated Dibenzofurans. 1

 Max Concentration = the highest predicted concentration at any receptor for a 24-hour or annual average. 2 Max Deposition Flux = Maximum predicted 

deposition rate per unit of soil area, at any receptor, over a daily or annual averaging period 
Biological Assessment of the Desert Rock Energy Project, April 2007 29

Chemical pollutants can accumulate in waterways, adversely impacting aquatic and riparian vegetation. 

Similar to the impacts of chemical air pollutants, chemical water pollutants can inhibit processes 

including photosynthesis, water regulation and respiration, which can reduce growth and development of 

plants. Chemical pollution deposited in waterways can also directly impact wildlife, including aquatic 

species and those species that depend on aquatic species; however, the concentrations of chemical water 

pollutants that wildlife in the project area will be exposed to are expected to be variable and depend on 

location and rainfall. Chemical pollutants deposited in or near waterways may also indirectly affect a 

number of wildlife species, particularly those who depend on riparian vegetation for foraging, nesting or 

breeding habitat. 

Aquatic wildlife could be affected by the deposition of particulates or by runoff from areas impacted by 

deposition. However, most streams in the vicinity of the proposed power plant, including the Chaco 

River, are ephemeral. The closest permanent water bodies are Morgan Lake (approximately 22 km) 

northwest of the proposed power plant and the San Juan River (approximately 28 km) north of the 

proposed power plant. 

Based on the results of air toxics modeling, it is estimated that the Desert Rock power plant could release 

up to 161 pounds of mercury per year through air emissions. The annual emission rate for mercury (161 

pounds per year) was derived from coal analysis data provided by BHP Billiton (URS 2007). A total of 71 

coal samples, taken from the coal seam designated for the proposed project in Areas IV South and V, 

were analyzed for mercury content. As a conservative approach, all values reported as “non-detect” were 

assumed to have the numerical magnitude of the analysis methods detection threshold of 0.05 ppm, 

resulting in a mean mercury concentration of 0.065 ppm. BHP Billiton is currently conducting additional 

coal sampling and analysis to verify the mean mercury content of the coal in Areas IV South and V. 

The following comments are important considerations regarding the estimation of mercury emissions and 

deposition rates. 1) It was assumed that 80 percent of the mercury generated by the combustion process is 

of an oxidized, particulate form, and that the remaining 20 percent consists of elemental mercury vapor. 

The control efficiency of the baghouse and wet scrubber, with respect to oxidized particulate mercury, 

will be no less than 95 percent, thus a maximum of 4 percent of the amount initially generated will be 

emitted, or approximately 26.8 pounds per year. Consequently, the balance of the total emissions 

(approximately 134.2 pounds per year) will be comprised of elemental mercury vapor (which is not 

removed by the control equipment); hence the total mercury removal efficiency of the control equipment 

is approximately 80 percent. 2) Deposition of a majority of the residual oxidized particulate mercury 

(about 26.8 pounds per year) will occur within about 25 kilometers from the proposed power plant. Due 

to its gaseous properties, only a small percentage of the elemental mercury vapor will settle out within 25 

kilometers from the plant (URS 2007). 

If, after operations commence, emissions testing indicates that total mercury removal is less than 80 

percent (which would be attributed to an actual ratio of oxidized to elemental mercury below 80/20), 

Sithe has committed to supplemental mercury control involving injection of activated carbon into the flue 

gas stream upstream of the control equipment. Elemental mercury will adsorb onto the surface of the 

carbon particles which are then captured (at a minimum 95 percent efficiency) in the control equipment 

(URS 2007). 

Mercury is an extremely mobile pollutant and is emitted from natural and anthropogenic sources, 

occurring in several different chemical states in the environment (USEPA 2005b). Mercury emissions 

may persist in vapor form in the atmosphere and travel large distances to be deposited, or may be 

deposited near the proposed plant site. Deposited mercury in water courses may be re-emitted to air, 

remain suspended or dissolve in the water, be deposited in sediments or absorbed or ingested by aquatic 
Biological Assessment of the Desert Rock Energy Project, April 2007 30

plants and wildlife (USFW 2005). A portion of mercury in water or sediment can be converted into 

methylmercury, which is easily absorbed by aquatic organisms and accumulates in aquatic vegetation, 

phytoplankton and invertebrates. The emitted mercury would consist of both particulates and vapors. The 

highest level of mercury emissions would occur within 0.36-km and 0.27-km from the stack (at an annual 

rate of 9.47E-03 mg/m2/yr) and most of that would be wet deposition. A small percentage of the total 

mercury coming out of the stack (0.2%) would be dry and the maximum deposition for this form of 

mercury (at an annual rate of 1.45E-07 mg/m2/yr) would occur about 5.3 km from the stack. 

For mercury, annual average deposition at Morgan Lake would be 1.36E-04 mg/m2/yr and the annual 

average deposition at the San Juan River where the proposed transmission line would cross the waterway 

would be 1.38E-04 mg/m2/yr. Currently, the maximum reported total mercury concentration in the San 

Juan River of 1.6 μg/L (microgram/liter) is below the Federal MCL (maximum contaminant level) for 

mercury of 2 μg/L, and the maximum dissolved mercury concentration in the San Juan River of 0.3 μg/L 

is below the chronic AWQC (ambient water quality criterion) of 0.7 μg/L. The average existing dissolved 

mercury concentrations in the San Juan River at Shiprock Bridge during the period 1994-2001 was 0.1 

μg/L. For the protection of aquatic wildlife, the federal chronic AWQC for dissolved mercury is 0.77 

μg/L (USEPA 2006). 

Based on the results of air toxics modeling, it is estimated that the proposed power plant would release a 

maximum of 161 pounds of mercury per year through air emissions. The emitted mercury would consist 

of both particulates and vapors. Some particulate mercury could be deposited both near to and far from 

the proposed plant site. Some portion of the mercury would be carried away by the atmosphere and would 

not be deposited in the region at all. It is estimated that about 19 pounds of mercury would be deposited 

within 25 km of the plant. The San Juan River is about 28 km from the power plant site. The actual 

quantity of mercury deposition that could eventually enter the San Juan River system or Morgan Lake 

directly or via runoff is difficult to quantify due to the high number of variables affecting deposition. 

Selenium is an essential element for both aquatic and terrestrial wildlife. However, it also has the 

narrowest range of what is beneficial and what is detrimental. Selenium has been shown to mitigate the 

toxic effects of mercury and other heavy metals in some organisms. There is also evidence that it may 

reduce the uptake of mercury in some aquatic organisms while increasing the mercury uptake in different 

organisms. Aquatic wildlife is exposed to selenium through ingesting food containing selenium and not 

through direct exposure to the chemical in water. Selenium is a bioaccumulative pollutant, meaning it 

accumulates in the tissues of aquatic wildlife. However, unlike mercury, concentrations of selenium do 

not increase significantly (biomagnify) in animals at each level of the food chain going from prey to 

predator (USEPA 2004). 

The AWQC for total selenium is 5.0 μg/L, and the mean concentration of total selenium in the San Juan 

River during the period of 1994–2001 is only 0.73 μg/L – 15 percent of the criterion. According to the 

USFWS (2005), selenium concentrations in fish from Morgan Lake may pose health risks to people and 

wildlife that consume a large amount of fish from the lake. However, the average dissolved selenium 

concentration measured in Morgan Lake was 1.0 μg/L which is substantially lower than the USEPA 

(2006) chronic water quality criterion (5.0 μg/L [total]) and the Navajo Nation Aquatic Habitat Criterion 

(2.0 μg/L) (USFWS (2005). 

Based on the results of air toxics modeling, it is estimated that the Desert Rock power plant could release 

up to 9,133 pounds of selenium per year through air emissions. The maximum deposition point for 

selenium also would be within .36 and .27 km from the stack, at a rate of 3.38E+00 mg/m2/yr. The 

annual average deposition at Morgan Lake would be 2.97E-02 mg/m2/yr and the annual average 

deposition at the San Juan River would be 3.01E-02 mg/m2/yr. The actual quantity of mercury deposition 
Biological Assessment of the Desert Rock Energy Project, April 2007 31

that could eventually enter the San Juan River system or Morgan Lake directly or via runoff is difficult to 

quantify based on the number of variables associated with depositon. 

The proposed power plant would result in the deposition of incremental quantities of mercury and 

selenium in the San Juan River and Morgan Lake and would incrementally add to existing concentrations. 

Heavy metal concentrations are likely to vary depending on location, prevailing winds and rainfall and a 

number of other factors. How this incremental increase in mercury and selenium would potentially affect 

different aquatic species, or those species which primarily feed on aquatic wildlife or vegetation, is 

difficult to quantify. Species would differ in the amount and pathway of heavy metals ingested, the rate of 

tissue bioaccumulation, and in what, if any, potential effects to growth, reproduction or longevity may 

occur. This would depend on many site specific and species specific factors. The ecological effects of 

mercury and selenium to aquatic wildlife remain greatly unknown and require additional study to fully 

understand (USFW 2005). Potential adverse impacts to area aquatic resources from incremental increases 

in mercury and selenium concentrations would be minor and long term. These impacts are not likely to 

result in a loss of species viability range-wide, nor cause a trend to federal listing. 

Sediment deposited into waterways can negatively impact aquatic plants in a number of ways. Sediment 

in water reduces light penetration, which can reduce the ability of plants to photosynthesize (USGS 

2006). Reduction in the ability of plants to photosynthesize can slow their growth and development. 

Sediment deposited in waterways can directly impact wildlife. For example, sedimentary particles can 

suffocate fish by clogging their gills and can also reduce respiratory efficiency of amphibians by adhering 

to their skin. Indirectly, sedimentation of waterways can reduce vegetation available as forage for wildlife 

when photosynthesis is impaired. 

Ground disturbance associated with construction and mining has the potential to increase sediments 

reaching the San Juan River. The power plant construction and BNCC mining operations must comply 

with Clean Water Act (CWA) regulations which require that surface-water runoff from constructed 

surfaces be controlled such as to “prevent, to the extent possible using the best technology currently 

available, additional contributions of suspended solids to streamflow, or runoff outside the permit area.” 

The CWA requires that discharges to streams meet all applicable water quality standards. Office of 

Surface Mining (OSM) approval procedures for controlling sediment transport include berms, terraces, 

sediment ponds, and other energy dissipative channel structures that allow water to pond and sediment to 

accumulate. Additionally, accidental fuel, lubrication or other hazardous material spills in the 

construction zone, depending upon the size, has potential to reach the San Juan River and adversely 

impact localized fisheries and/or downstream habitats such as nursery backwaters. 

Potential impacts to water quality from sedimentation or hazardous material spills would be mitigated by 

implementation of the construction Stormwater Management Plan and by the project Hazardous 

Materials Handling and Response Plan. Following implementation of these plans, potential impacts to 

water quality from increased sedimentation would be minor

6.3.2 Ground Water Effects 

Groundwater will be pumped from the Morrison aquifer to supply water for the Desert Rock Power Plant 

cooling processes. The average annual water consumption demand of the proposed Desert Rock Power 

Plant is estimated at 4,950 ac/ft per year, or 3,070 gallons per minute (gpm), of continuous flow for a 

period of 40 consecutive years. This is the volume used in well impact modeling simulations for the water 

well field location (URS 2007). 

 

A groundwater predictive computer model (Miller Brooks 2007), using the program MODFLOW, was 

constructed to evaluate the various combinations of well locations under Alternative B. The model 
Biological Assessment of the Desert Rock Energy Project, April 2007 32

boundaries were constructed as a rectangle, from near Morgan Lake south to Burnham and from Shiprock 

east to Fruitland. The source aquifer was the Morrison Formation, assumed to be confined and at a 

constant thickness of 600 feet. Hydraulic conductivity for the Morrison Formation was estimated at 0.075 

to 0.175 ft/day. Simulations were run for 20 years and for 40 years. Drawdown contour lines of ten feet or 

greater were mapped onto the model surface. At the center of the northern portion of the proposed well 

field, drawdowns were 1,885 feet for the 20-year simulation and 2,010 feet for 40 years. The southern 

portion of the proposed well field incurred drawdowns of 1,920 feet for 20 years of pumping and 2,020 

feet for 40 years of pumping. If both well field locations are used, the maximum drawdown would be 

experienced at the southern center, and would total 960 feet for 20 years of pumping and 1,020 feet over 

40 years. 

After 40 years of pumping, a large cone of depression in the potentiometric surface of the Morrison 

Formation would be experienced at the project site. This cone would decrease radially from the center of 

the wellfield and approach zero feet of drawdown at about 10 miles. 

6.3.3 Stream Flow Effects 

Given the distance, greater than 10 miles, between the water well field and San Juan River no effects to 

streamflows are expected from the extraction of 4,950 ac/ft per year from the Morrison Aquifer (URS 

2007). 

For mining operations, BNCC will utilize approximately 600 ac/ft per year of consumptive water rights 

from the San Juan River, which will be stored in Morgan Lake. BNCC use of existing San Juan River 

water rights and the effects on stream flow in the San Juan River have been analyzed and documented in 

the Final Environmental Impact Statement Navajo Reservoir Operations Navajo Unit - San Juan River 

New Mexico, Colorado, Utah (USDI Bureau of Reclamation 2006). Therefore, there would be no 

additional effects to stream flows in the San Juan River resulting from the proposed action. 

6.4 Infrastructure Related Effects 

6.4.1 General Habitat Effects 

Construction and operation of project components including the power plant facility, access roads, 

transmission lines and water well field will result in temporary ground disturbance, as well as the 

development of permanent structures that alter habitat for vegetation and wildlife in the analysis area. 

Table 4-1 in Section 4.2.1 above displays the disturbance per project component. 

Construction and operation of the power plant site is expected to disturb 149 acres of primarily grasslands 

(50%) and shrublands (49%). Construction and operation of the preferred transmission line alignment 

(Segments A, C and D) would disturb approximately 1,205 acres of primarily shrublands (49%) and 

grasslands (39%). Segment D contains portions of canyonlands (13%) and blackbrush-ephedragreasewood shrublands (13%). The sub-alternative transmission line (Segments B, C and D) would result 

in a total of approximately 1,373 acres of disturbance; 168 more acres than the preferred alternative that 

includes transmission line Segment A (503 acres). Construction and operation of the alternative 

transmission line Segment B would directly impact mostly inter-mountain basin mixed salt desert scrub 

lands and (50%) inter-mountain basin semi-desert grasslands (43%). 

Access road construction would permanently remove approximately 21 acres inter-mountain basin semidesert grasslands (57%) and inter-mountain basin mixed salt desert scrub lands and (22%). 
Biological Assessment of the Desert Rock Energy Project, April 2007 33

The water well field Alternative A would encompass about 890 acres, almost all of which is intermountain basin greasewood flats (93%). Vegetation would be removed from maximum of 45 acres 

within the water well field for construction, drilling and operation of 20 water wells, the construction of 

collector pipelines and an access road. This alternative would necessitate construction of a 12.4 mile 

utility corridor/water pipeline which would directly impact 150 acres of vegetation. The dominant 

vegetation communities that occur along the utility corridor/water pipeline are inter-mountain basin 

mixed salt desert scrub lands (42%), inter-mountain basin semi-desert grasslands (21%), and intermountain basin greasewood flats (34%). Total acreage for water well field Alternative B would be 890 

acres; the vegetation community in this area is co-dominated by inter-mountain basin semi-desert 

grasslands (33%) and inter-mountain basin mixed salt desert scrub (50%). Approximately 10.5 acres of 

piñon-juniper woodland occurs within the proposed water well field. 

Wildlife habitat within the BNCC Lease Areas IV and V would gradually be impacted on an ongoing 

basis as mining activities expand over time. A maximum of 13,051 acres would be removed and altered 

over the life of the lease areas, primarily grassland (68%), shrublands (27%), and blackbrush-ephedragreasewood shrublands (5%). 

Disturbance and removal of soil has potential to directly and indirectly impact vegetation in the project 

area. Temporary soil disturbance and permanent soil removal will likely kill live individuals, and may 

negatively impact seed sources if dead individuals are damaged or removed. Likewise, creation of manmade structures including large buildings, roads, and mines may alter natural seed dispersal patterns, 

which could impact recruitment of plant species from living and dead stock. The density and diversity of 

vegetation species would be modified in areas reclaimed following construction. Disturbance of natural 

plant communities can lead to invasion of exotic species, which may be more likely to outcompete 

natives. 

Construction and operation of the power plant facility, access roads, transmission lines and water wells is 

likely to impact wildlife via two primary mechanisms: 1) through removal of habitat, and 2) by altering 

normal movement routes. Disturbance and removal of soil and vegetation will directly and indirectly 

impact wildlife by removing habitat that is used for foraging, burrowing/nesting, and breeding. In 

addition to direct physical removal of habitats, construction of power plant facilities, transmission lines, 

access roads and water well facilities is likely to impede normal wildlife movement patterns. Because of 

the size of the physical structures themselves, wildlife movement corridors may be disrupted. This may 

result in localized clumping and restricted dispersal among sub-populations. Over time, restricted 

movement and dispersal could reduce genetic diversity in the population as a whole, or could limit the 

ability of individual sub-populations to recolonize following random demographic or environmental 

events, for example disease epidemics or extreme drought. 

6.4.2 Noise Effects 

Unwanted and excessive noise generated from the proposed action has the potential to adversely impact 

wildlife, particularly if the noise creates disruption within their nesting, foraging or breeding habitats. 

Noise is generally defined as unwanted sound that is associated with human activity or human-created 

infrastructure that disrupts normal activity patterns. The effect of noise on wildlife has only recently been 

considered a potential threat to animal health and long-term survival. Assessing the impact of noise on 

wildlife is complicated by the variations between different species and between individuals within a 

single population. In addition, variation can arise depending on the characteristics of the noise and its 

duration, the life history characteristics of the species, habitat type, season, activity at the time of 

exposure, sex and age of the individual, level of previous exposure, and whether other physical stresses 

such as drought are occurring around the time of exposure (Busnel 1978). Despite these inherent sources 
Biological Assessment of the Desert Rock Energy Project, April 2007 34

of variation, the general consensus among acoustic ecologists is that noise can affect an animal's 

physiology and behavior, and if it becomes a chronic stress, noise can be injurious to an animal's energy 

budget, reproductive success and long-term survival. 

Long-term studies have shown that depending on the characteristics of the noise and the species, the 

reaction of the animal to noise can range from mild annoyance to panic and escape behavior (Fletcher 

1980). Mild annoyance may cause wildlife to avoid or temporarily evacuate an area until the source of 

the noise abates. Panic or escape behavior may result in accidental injury, as animals could fall, run into 

objects or become trampled in panic. More specifically, studies have documented a short-term increase in 

heart rate among ungulates (Larkin 1996), reduced ability of small mammals to detect predators (Immel 

1995), and alteration of nesting and roosting sites among raptors (Larkin 1996). 

Noise is expected to be generated during construction of the proposed project components, including the 

power plant facilities, transmission line, access roads and water well field. The construction phase of the 

proposed project is projected to continue for at least 36 months. Conventional construction activities in 

the project area would result in a short-term increase in the ambient noise level resulting from the 

operation of construction equipment. The increase in noise levels would be primarily restricted to the 

areas surrounding construction zones and the magnitude of noise generated would depend on the type of 

construction activity, equipment used, duration of the activity, and distance between the noise source and 

the receiver. The DEIS provides detailed information on the maximum noise levels generated by typical 

construction equipment; however, the average sound level generated by construction equipment is 89 

dBA at 50 feet from the source (URS 2007). Because construction noise is expected to be below the 90 

dBA hourly levels recommended by the Federal Transit Administration, general impacts from noise are 

expected to be low. 

Once construction is completed, operation of the project components is expected to result in the ongoing 

generation of noise and vibrations throughout the project area for the lifetime of the project. According to 

the DEIS, operation of the power plant facility is expected to generate less than 30 dBAL at nearby sound 

receptors, which is below residential land use requirements. Vibrations resulting from operation of the 

power plant are also expected to have negligible impacts, as the equipment used in the power plant 

facility is designed to produce very low vibration levels and are designed to shut down automatically if an 

unforeseen imbalance develops. 

6.4.3 Human Activity Effects 

Construction and operation of the Desert Rock Energy project will necessitate a substantial increase in 

human presence above existing levels. For example, the DEIS projects that vehicles will travel 10 miles 

per day during the 36-month construction of the power plant, 25 miles per day during the 12 month 

construction of access roads, and 50 miles per day during the 6 month construction of the transmission 

lines, all with an operating schedule of 10 hours per day, 6 days per week, 52 weeks per year (URS 2007). 

The DEIS also specifies that an estimated 200 employees on rotating shifts will be required for 

construction and normal operations and maintenance of the power plant and associated facilities (URS 

2007). Thus, the proposed project will result in a considerable increase in human presence in the project 

area, which is likely to impact both vegetation and wildlife. 

Human presence has the potential to disturb vegetation in the project area, particularly in areas where 

humans travel beyond the boundaries of established roads, walkways or structures. Vegetation could be 

directly impacted by humans trampling or damaging individual plants or plant communities and could be 

indirectly impacted by humans disrupting soils outside of established travel routes. Disruption and 

degradation of soil can lead to increased wind and water erosion, making it difficult for vegetation to 

become or remain established. Cryptogamic soil crusts, if encountered, are particularly vulnerable to 
Biological Assessment of the Desert Rock Energy Project, April 2007 35

human disturbance, as these crusts can be disrupted by very few passes with a vehicle or human footprint 

(Belnap and Gillette 1997). 

In general, wildlife tend to avoid contact or confrontation with humans. As such, wildlife in the Desert 

Rock analysis area may temporarily avoid areas where human disturbances are occurring, or may 

permanently emigrate from areas where human presence is more constant. This may result in alterations 

of nesting, foraging and breeding behavior in species that are particularly sensitive to human presence 

(Stillman et al. 2002). Wildlife may be more sensitive to human presence during significant periods of 

their annual cycles, including the breeding season. Construction and operation of the proposed project 

will require extensive vehicle travel which may increase the likelihood of collisions with wildlife. 

Vehicle strikes have the potential to adversely impact a variety of wildlife species, including rabbits, 

coyotes, fox, birds, and deer. 

Depending upon the activity occurring, the proximity of the activity to wildlife and the species 

encountered, human activity impacts would range from negligible to major. A major impact would be 

attributable to harm caused to wildlife, either accidentally or intentionally from human activity in the 

area, that could result in serious injury or death. 

6.5 Effects to Raptors and Migratory Birds 

Vegetation clearing and development of electrical transmission and distribution lines may all have a 

negative effect on raptors and migratory birds by causing direct mortality and disrupting breeding, 

nesting, and foraging behaviors. In addition, nests may be disturbed during the construction phase, and 

less area will be available for or desirable for nesting as a result of the proposed project. 

Power poles provide attractive perch, nest, and roost sites, especially in relatively flat and treeless areas, a 

positive impact of powerline construction for raptors. However, the size of some birds makes it possible 

for them to simultaneously contact two charged objects (phases or conductors) or one charged object and 

a ground wire. Most problems occur on distribution lines 69kV or less, particularly at junction poles and 

transformers. Raptors and large birds are electrocuted through phase to phase and phase to ground 

contacts, while small birds can be electrocuted from bushings and transformers and other pole hardware. 

Studies have shown that golden and bald eagles suffer some of the highest mortalities; one study based on 

ten years of data collected from 13 western states and Canada found that out of 1,450 confirmed raptor 

electrocutions, 272 were golden eagles. 

In the project area, raptors (i.e. golden eagles and ferruginous hawks) and corvids (i.e. crows, ravens and 

magpies) are most likely to be affected by electrocution due to their relatively wide wingspans and 

tendency to use poles as nesting platforms and perches from which they survey for prey (Lehmann 2001). 

Raptor collisions are documented most frequently on transmission lines greater than 69 kV. Collisions 

occur when birds cross transmission lines in daily use areas (i.e. moving from roosting to foraging 

habitat); when birds migrate through an area; and when rain, fog, night and other low visibility conditions 

can contribute to collision risk. Other factors that contribute to birds colliding with transmission lines are 

the body size of the bird, maneuverability, and the height that birds commonly fly. Few studies on bird 

flight diverters have been completed, but most found they reduced collision rates (Crowder and Rhodes 

1999). 

Other potential effects on raptors and migratory birds include proximity to noise and human activity 

(discussed above) to breeding and foraging areas. As with other area wildlife, increases in area noise and 

human activity would impact area raptors and migratory birds. 
Biological Assessment of the Desert Rock Energy Project, April 2007 36

6.6 Federally Listed Species Effects 

The project area provides potential habitat for six federally listed species and one candidate species: bald 

eagle, southwestern willow flycatcher, yellow-billed cuckoo, Colorado pikeminnow, razorback sucker, 

Mancos milkvetch, and Mesa Verde cactus. Effects to these species are described in detail in this section. 

Species accounts include their federal status, known distribution and habitat requirements, 

presence/absence or potential to occur in the project area, and potential effects to each species. 

Also included in this section are recommended conservation and/or mitigation measures to minimize or 

eliminate potential impacts to federally listed flora and fauna species with potential to occur in the project 

area. 

6.6.1 Bald Eagle (Haliaeetus leucocephalus) 

Status: Federally Threatened 

Distribution and Habitat: Bald eagles are associated with aquatic habitats with forested shorelines or 

cliffs throughout North America. Breeding populations of bald eagles in the Rocky Mountain region are 

increasing (Buehler 2000); however, there are no verified nesting pairs along the San Juan River in 

northwestern New Mexico. The southwestern U.S. (including northwestern New Mexico) does, however, 

support healthy populations of wintering bald eagles. Wintering habitats are typically associated with 

aquatic areas with some open water for foraging; however, eagles wintering in the southwestern U.S. may 

occupy arid habitats (Buehler 2000). 

Winter habitat suitability is defined by food availability, presence of roost sites that provide protection 

from inclement weather, and absence of human disturbance (Buehler 2000). Wintering bald eagles are 

opportunistic foragers and winter diets may vary greatly across its range depending on food availability 

(Stalmaster 1987, Brown 1993). Forage may include a mix of live prey and carrion (Brown 1993) and 

consists of birds, mammals, or fish. Bald eagles prefer roost trees that are large and open (Keister and 

Anthony 1983, Chester et al. 1990, Buehler et al. 1991); in the western U.S., most roost trees are conifers 

(Keister and Anthony 1983, Buehler 2000) except in riparian areas where cottonwoods are typically used. 

While some wintering areas are absent of human activity, bald eagles will tolerate some human activity in 

areas of high prey availability (Buehler 2000). 

Potential to Occur in the Project Area: In San Juan County, bald eagles are most common during the 

winter months and there are no verified nesting pairs along the San Juan River. The nearest known 

nesting sites occur approximately 40 miles northeast of the proposed project area in southern Colorado. 

On the Navajo Nation, bald eagles are considered winter migrants and are generally only present from 

November to March. However, the San Juan River corridor does provide potential nesting habitat and 

nesting may occur in the future (Dave Mikesic, NNDFW, pers. comm.). 

Within the analysis area, the San Juan River provides quality foraging habitat for wintering bald eagles, as 

this perennially flowing river provides a plentiful source of fish, a primary component of the bald eagle 

diet. In addition, cottonwood trees which occur along and near the San Juan River provide wintering bald 

eagles with perching and roosting sites. Bald eagles are likely to utilize the open shrublands, extending up 

to 5 miles beyond the San Juan River, to forage for small mammals and scavenge for carrion. Limited 

roosting and nesting opportunities also exist in scattered patches of cottonwoods and/or lone trees along 

the Chaco River and, to a less extent, along the margins of Morgan Lake. While bald eagles may 

incidentally occur anywhere in the project analysis area, and at any time of the year, they would most 

commonly be expected to occur along the San Juan River corridor. 
Biological Assessment of the Desert Rock Energy Project, April 2007 37

Ecosphere biologists conducted bald eagle roosting/nesting surveys within a 1/4-mile radius of the 

proposed transmission line crossing of the San Juan River on 28 February 2006 and 1 March 2006. 

Surveys were conducted according to USFWS accepted methodologies that consisted of dawn and dusk 

ocular surveys for eagles for 2 successive days during the winter. There were no winter roosting or nest 

sites detected in the vicinity of the San Juan River transmission line crossing. Additionally, while it is 

common to observe bald eagles traveling the San Juan River corridor during winter months, no bald 

eagles were observed during the 2006 surveys. However, in August 2004, one juvenile bald eagle was 

spotted in the west-central portion of the study area and another juvenile was identified near the northern 

boundary of the study area (Ecosphere unpublished data). 

Project Effects to Bald Eagle: There would be no direct loss of suitable roosting or nesting habitat due 

to the removal of cottonwood trees across the San Juan River floodplain. While no nest or roost trees 

occur within the proposed right-of-way, there are tree nesting and roosting opportunities both up and 

down stream from the proposed transmission line crossing of the San Juan River. Several opportunities 

exist within 1⁄4-mile of the proposed right-of-way. 

During construction of the proposed transmission corridor across the San Juan River, eagles could be 

affected by noise and human activity disturbances due to proximity of the crossing to suitable nesting and 

roosting habitat. Bald eagles appear to be particularly sensitive to noise and human activity during the 

breeding season with distance to noise source as the primary factor of human activity determining bald 

eagle response (Grubb et al. 1992). Similarly, human activity can impact bald eagle distribution, causing 

bald eagles to avoid inhabiting developed areas (Buehler et al. 1991). Potential effects to bald eagle 

would be temporary avoidance of the river corridor during construction activities. 

The project component with the greatest potential to impact bald eagles in the project area is the proposed 

transmission line span of the San Juan River. The proposed transmission line will be placed adjacent and 

parallel to an existing power line. While this span would not directly impact individual roost or nest trees, 

the addition of electrical transmission towers and lines would increase the potential for eagle line 

strikes/collisions and electrocution from perching on or near tower conductors. Raptor collisions are 

documented most frequently on transmission lines greater than 69 kV. The addition of electrical 

transmission towers and lines would increase the long term potential for bald eagle line strikes/collisions 

and electrocution from perching on or near tower conductors. 

Recommended Conservation / Mitigation Measures: 

• Timing restrictions for construction and maintenance of transmission towers within and above the 

San Juan River floodplain (i.e. all towers within 1⁄4-mile of the San Juan River) and similar 

restrictions on timing for stringing conduit across the San Juan River. Work should not be 

conducted between November 1 and March 31 to avoid disturbance to over-wintering bald eagles. 

• Should a bald eagle(s) be observed perched within 1⁄4-mile of the transmission line crossing of the 

San Juan River, or of tower placements near the Chaco River, no construction activities should 

commence until the eagle leaves the area of its own accord. 

• Hospital-grade mufflers should be installed on all permanent project components that generate 

noise above acceptable levels in areas that are likely to be utilized by bald eagles for roosting or 

foraging. 
Biological Assessment of the Desert Rock Energy Project, April 2007 38

• Proposed electrical transmission and distribution lines will be designed and constructed utilizing 

"raptor-safe" design. The most complete manual on this work is " Suggested Practices For Raptor 

Protection On Power Lines: The State of the Art in 1996” (APLIC 1996). 

• Although few studies on bird flight diverters have been completed most found they reduced 

collision rates (Crowder and Rhodes 1999), therefore diverters will be installed on all lines at the 

river crossing, per recommended specifications. 

• Spacing of phase-to-phase and phase-to-ground wire should be sufficient to allow passage for 

large winged birds (Manville 2006). To minimize electrocutions that may occur while eagles are 

perching, installation of cross-arm braces on steel distribution poles or installation of artificial 

perches on wooden distribution poles is recommended (Manville 2006). 

Determination of Effect: The proposed action may affect, is likely to adversely affect bald eagle. 

6.6.2 Southwestern willow flycatcher (Empidonax traillii extimus) 

Status: Federally Endangered with Designated Critical Habitat 

Distribution and Habitat: Southwestern willow flycatchers are neotropical migrants that occur in dense 

riparian habitats along streams, rivers, and other wetlands where cottonwood, willow, boxelder, tamarisk, 

Russian olive, buttonbush, and arrowweed are present (USFWS 2002). Nests are found in thickets of trees 

and shrubs primarily 13 to 23 feet in height, among dense and homogenous foliage (USFWS 2002). 

Habitat occurs at elevations below 8,500 feet (USFWS 2002). This species breeds locally along the 

Colorado River in the Grand Canyon near the mouth of the Little Colorado River, and south of Yuma; at 

the Little Colorado River headwaters near Greer and Eagar; very locally along the middle Gila, Salt, and 

Verde rivers; middle to lower San Pedro River; and upper San Francisco River near Alpine (USFWS 

2002). In addition to being protected under ESA, this species also is protected by the Migratory Bird 

Treaty Act (MTBA). 

Potential to Occur in the Project Area: The breeding range of southwestern willow flycatcher extends 

into the Navajo Nation, and breeding has been documented along the San Juan River. Despite the 

presence of suitable habitat, no breeding southwestern willow flycatchers are known to occur in the 

project area. There is only one known historic breeding territory for southwestern willow flycatchers in 

San Juan County; this location occurs along the San Juan River at a location that is northwest of the 

proposed project area on the Navajo Nation. Migrants have been commonly recorded along the San Juan 

River during Bureau of Land Management Farmington Field office (BLM/FFO) surveys. The BLM has 

no documented occurrences of breeding southwestern willow flycatchers (Barney Wegener BLM/FFO, 

pers. comm. 2006). 

Migrants have the potential to occur in the project area from May to August and are most likely to occur 

along the San Juan River and at Morgan Lake. Within the project area, breeding habitat for this species is 

present along the San Juan River crossing and at Morgan Lake. These habitats consist of dense riparian 

vegetation and active wetlands, backwaters and sloughs. Because water only occurs in the Chaco River 

seasonally and given the absence of dense vegetation, it is not considered potential breeding habitat. 

Sections of vegetation along the Chaco River do provide potential migratory stopover habitat for 

southwestern willow flycatchers. 

USFWS protocol surveys conducted in the project area in 1998 and 1999 indicated the presence of 

southwestern willow flycatchers in the 2nd and 1st survey periods, respectively, but flycatchers were not 
Biological Assessment of the Desert Rock Energy Project, April 2007 39

detected during the 3rd survey period in either year (USDI 2001). In surveys conducted in the project area 

in 2004 by Ecosphere, six southwestern willow flycatchers were detected during the first survey period at 

Morgan Lake and no individuals were documented near the San Juan River. No detections were 

documented beyond the first survey period in 2004 at either Morgan Lake or near the San Juan River. In 

the most recent protocol surveys of the project area, conducted in June 2006 by Ecosphere, one willow 

flycatcher was detected near the transmission line crossing along the San Juan River during the 1st survey 

period. During the 2nd and 3rd survey periods no individuals were detected, which according to USFWS 

guidelines suggests that the flycatcher detected during the 1st survey period was a migrant, rather than a 

resident breeder. No flycatchers were detected near Morgan Lake in 2006 during any survey period. 

Preliminary surveys conducted by Ecosphere along the Chaco River in 2006 revealed that this area 

provided limited habitat for southwestern willow flycatcher and it was determined that this species is not 

likely to occur near the Chaco River. 

Project Effects to Southwestern Willow Flycatcher: There would be no direct removal of suitable 

nesting habitat for this species in any of these three habitat areas; San Juan River, Morgan Lake, and 

Chaco River. Currently, there is an approximately 50-foot wide fringe of previously disturbed tamarisk 

extending for approximately 200-feet south of the San Juan River along the west edge of the 

Transmission Line Segment D. At the time of the 2006 presence/absence surveys (negative results) in 

this area, this tamarisk fringe did not represent good nesting substrate due to its relatively short height 

(less than 6-ft). However, in 5 years or more, these tamarisk patches have potential to mature into 

suitable breeding habitats for the southwestern willow flycatcher. Should this tamarisk fringe require 

cutting or mowing in order to place transmission towers, it is recommended that the clearing occur 

outside the willow flycatcher breeding period from May 1 through Aug 30 and prior to the patch maturing 

to potential suitable breeding habitat status. 

If the tamarisk patch described above can be avoided, construction of transmission towers within the San 

Juan River floodplain has the potential to impact southwestern willow flycatcher as a result of increases in 

noise and human activity in the immediate area of suitable migratory and breeding habitats. These 

potential impacts would consist of temporary avoidance of the area during construction and would be 

avoided or minimized if construction of these towers is accomplished outside of the breeding period. 

The proposed action would not impact southwestern willow flycatchers that may be present around the 

perimeter of Morgan Lake as these habitats are more than 1⁄2 mile away from the proposed Transmission 

Line Segment D and shielded from line-of-sight by topography. 

Minor impacts in the form of temporary avoidance due to noise and human activities are possible during 

construction of Transmission Line Segment B where tower placements and line stringing activities are 

within 1⁄4-mile of the Chaco River and occur during the breeding season. This potential impact assumes 

that willow flycatcher may, in the future, utilize the Chaco River at a minimum as migratory stopover 

habitat. To date there are no records of flycatchers along the Chaco River; however, only limited surveys 

have been completed in this drainage. Avoidance of construction activities during the breeding season 

within 1⁄4-mile of the Chaco River would minimize or eliminate the potential of impacting willow 

flycatchers. These impacts to southwestern willow flycatcher would be insignificant and discountable. 

Construction of the proposed power plant and associated infrastructure, water well field and mining 

operations would have no effect to southwestern willow flycatchers or potential habitats. 

Recommended Conservation / Mitigation Measures: 

• Timing restrictions for construction of transmission towers and stringing of conduit lines, as well 

as other construction and maintenance activities within and above the San Juan River floodplain 
Biological Assessment of the Desert Rock Energy Project, April 2007 40

and within 1⁄4 mile of the Chaco River. Work should not be conducted between May 1 and 

August 30 to avoid disturbance to migrant or potential breeding flycatchers.

• Should clearing of riparian vegetation in areas of suitable flycatcher habitat be necessary, Desert 

Rock Energy LLC in coordination with the Navajo Natural Heritage Program and the USFWS, 

will develop a compensatory mitigation plan to offset the potential loss of habitat.

• Because southwestern willow flycatcher habitat along the Chaco River was not subject to 

protocol surveys in 2006 in all survey periods, the Chaco River should be resurveyed for willow 

flycatchers if habitat conditions change over the course of project development and construction. 

Determination of Effect: The proposed action may affect, is not likely to adversely affect southwestern 

willow flycatcher. 

6.6.4 Colorado pikeminnow (Ptychocheilus lucius) 

Status: Federally Endangered with Designated Critical Habitat 

Distribution and Habitat: The Colorado pikeminnow is a cyprinid fish species endemic to the Colorado 

River Basin. The species was once distributed throughout the major rivers and tributaries of the basin in 

Wyoming, Colorado, Utah, New Mexico, Arizona, Nevada, and California. This species is the largest 

cyprinid native to North America. The American Fisheries Society changed the common name for the 

Colorado squawfish to Colorado pikeminnow in 1998 (Nelson et al. 1998). Adults attain a maximum size 

of about 1.8 meters (m) total length (TL) and weigh 36 kilograms (kg). 

The Colorado pikeminnow was first included in the List of Endangered Species issued by the Office of 

Endangered Species on March 11, 1967 (32 FR 4001) and was considered endangered under provisions of 

the Endangered Species Conservation Act of 1969 (16 U.S.C. 668aa). The Colorado squawfish 

(pikeminnow) was included in the United States List of Endangered Native Fish and Wildlife issued on 

June 4, 1973 (38 FR No. 106; i.e., the red book, and it received protection as endangered under Section 

4(c)(3) of the original ESA of 1973. A revised Colorado Squawfish (pikeminnow) Recovery Plan was 

approved on August 6, 1991 (USFWS 1991), and critical habitat was designated on March 21, 1994 (59 

FR 13374). A total of 1,148 miles (1,848 kilometers (km) of critical habitat have been designated for the 

Colorado pikeminnow in the Upper Colorado River Basin. There is no critical habitat designated in the 

Lower Basin. The Colorado pikeminnow recovery plan was further amended and supplemented in 2002 

(USFWS 2002b). In 2003, an augmentation plan for Colorado pikeminnow in the San Juan River was 

approved by the USFWS (Ryden 2003). 

Adult fish inhabit large to medium rivers and are found in turbid, deep pools with a strong current and 

rocky or sand substrate. Juvenile fish use backwater and side channel habitats with silt and sand substrates 

and largely consume insects and crustaceans. Pikeminnow spawn when water temperatures approach 18o 

centigrade (C) in July or August. Preferred spawning sites are riffles with gravel or cobble substrates 

(Lamara et al. 1985). The Colorado pikeminnow have been collected over 150 mile section of the San 

Juan River from Lake Powell to near Farmington, New Mexico (Ryden 2000). 

Potential to Occur in the Project Area: On the Navajo Nation, the Colorado pikeminnow has been 

documented throughout the San Juan River from Shiprock to Lake Powell. The majority of adults use the 

stretch of the San Juan River about 11 km downstream of Shiprock to just downstream of Four Corners. 

Irrigation canals that feed into the San Juan River may also provide potential habitat. Because Colorado 
Biological Assessment of the Desert Rock Energy Project, April 2007 41

pikeminnow require perennial bodies of water, they are not expected to occur within the Chaco River 

which is an intermittent stream. 

Wild Colorado pikeminnow were generally believed to have been extirpated from the San Juan River 

after the closure of Navajo dam in 1965, however, two adult pikeminnow were collected in 1987 from the 

San Juan River between Shiprock and the Four Corners area confirming the species was still present 

(Platania 1990). Subsequent mark/recapture studies estimated that a total of 19 wild Colorado 

pikeminnow inhabited the San Juan River (Ryden 2000). These adult fish were found to use habitats 

primarily between river miles (RM) 109 to RM 142, generally between Shiprock, New Mexico and south 

of Aneth, Utah. Spawning has been documented to occur within a region of high channel complexity 

between RM 133.4 to RM 129.8, near the Four Corners Region (Ryden 2000). It is estimated that 

spawning occurs from July 8 to August 12 in the San Juan River (Platania 2000). Larval and juvenile 

pikeminnow have been collected from low velocity habitats downstream of RM 130 and Shiprock to the 

confluence of Lake Powell (Ryden 2000). 

Experimental stocking of Colorado pikeminnow in the San Juan River was initiated in 1996. From 1996 

through 2000, approximately 832,000 larval pikeminnow were stocked in the San Juan River within 

designated critical habitat. The relative success of these efforts was high with an over winter retention 

rate of about 62%. Due to the success of this initial stocking effort, a seven year pikeminnow stocking 

plan was initiated in 2002 which committed to the stocking of 300,000 juvenile pikeminnow at RM 180.2 

and RM 158.6, between Farmington and Shiprock (Ryden and McAda 2003). 

In addition, the San Juan River Recovery Program released flow recommendations for the San Juan River 

in 1999 that was believed to be needed to allow for the natural recovery of the Colorado pikeminnow 

(Holden 1999). These flow recommendations essentially described flows that would mimic the natural 

hydrograph to include operating Navajo Reservoir in such a manner to enhance flow conditions 

throughout designated critical habitat. 

Other pikeminnow recovery activities have been focused on allowing this species to more freely access 

upstream portions of the San Juan River. To facilitate this, the Cudei Diversion (RM 140), south of 

Shiprock, was removed and the Hogback Diversion structure was made freely passable in 2001. Also, in 

2003, a selective fish passageway was completed at the Public Service Company of New Mexico (PNM) 

weir in Kirtland (RM 150) to allow for native fish, including Colorado pikeminnow, species to access the 

San Juan River above the weir. In addition, non-native fish removal from the San Juan River, focusing 

primarily on channel catfish, has also been successful resulting in reduced predation from this species on 

juvenile Colorado pikeminnow (Dale Ryden USFWS, pers, comm. 2006). 

In 2004, six Colorado pikeminnow were collected from the lower 5 miles of the Animas River during the 

course of a fishery survey not directly tied to the San Juan Recovery Program indicating that the range of 

the Colorado pikeminnow may be expanding. This was the first fully documented occurrence of this 

species occurring in the Animas River (Zimmerman 2005). 

During the course of 2006 fall monitoring studies conducted in the San Juan River, 175 Colorado 

pikeminnow were collected during the first five days of sampling which extended from Farmington (RM 

180) to the Four Corners area (RM 120). No wild Colorado pikeminnow were collected during the course 

of this survey and it’s hypothesized that none remain in the system (Dale Ryden USFWS, pers. comm. 

2006). 

Critical habitat for this species occurs in the San Juan River across the northern portion of the project 

area. Colorado pikeminnow is expected to be present at certain times of the year, particularly during the 

summer months, within the San Juan River corridor portion of the proposed action area. 
Biological Assessment of the Desert Rock Energy Project, April 2007 42

Project Effects to Colorado Pikeminnow: The proposed Transmission Line Segment D would span 

Colorado pikeminnow critical habitat. Construction of the proposed alignment may result in 2 tower sites 

being placed within the 100-year floodplain of the San Juan River resulting in permanent disturbance to 

approximately 1.8-acres of upland habitats. The 100-year floodplain is considered part of the critical 

habitat designation. Primary constituent elements are physical and biological attributes that essential to 

species conservation and include but are not limited to: 

• Water – this includes a quantity of water of sufficient quality, 

• Physical Habitat - includes areas of the Colorado river system that are inhabited or 

potentially habitable by fish for use in spawning, nursery, feeding, and rearing or corridors 

between these areas, and 

• Biological Environment – food supply, predation and competition (Federal Register 

1991). 

Construction of the Transmission Line Segment D would not result in adverse modification to primary 

constituent elements within designated critical habitat following the implementation of mitigation 

measures. No construction activities would occur within or adjacent to the San Juan River stream channel 

for the proposed action. 

Ground disturbance associated with construction within the floodplain has the potential to increase 

sediments reaching the San Juan River. Additionally, accidental fuel, lubrication or other hazardous 

material spills in the construction zone, depending upon the size, has potential to reach the San Juan River 

and adversely impact localized fisheries and/or downstream habitats such as nursery backwaters. 

The average annual water consumption demand of the proposed Desert Rock Power Plant is estimated at 

4,950 ac/ft per year, or 3,070 gallons per minute (gpm), of continuous flow for a period of 40 consecutive 

years. Groundwater is proposed to be pumped from the Morrison aquifer to meet this need (URS 2007). 

At the center of the northern portion of the proposed well field, drawdowns were 1,885 feet for the 

20-year simulation and 2,010 feet for 40 years. The southern portion of the proposed well field incurred 

drawdowns of 1,920 feet for 20 years of pumping and 2,020 feet for 40 years of pumping. If both well 

field locations are used, the maximum drawdown would be experienced at the southern center, and would 

total 960 feet for 20 years of pumping and 1,020 feet over 40 years. 

After 40 years of pumping, a large cone of depression in the potentiometric surface of the Morrison 

Formation would be experienced at the project site. This cone would decrease radially from the center of 

the wellfield and approach zero feet of drawdown at about 10 miles (Brooks and Miller 2007). Given the 

distance between the water well field and San Juan River, and the depth of the Morrison aquifer, no 

effects to streamflows are expected from the extraction of 4,950 ac/ft per year from the Morrison Aquifer 

(URS 2007). 

For mining operations, BNCC will utilize approximately 600 ac/ft per year of existing water rights from 

the San Juan River. Effects from water depletion to Colorado pikeminnow under BNCC’s consumptive 

San Juan River water rights have been evaluated and documented in the Final Environmental Impact 

Statement (FEIS) Navajo Reservoir Operations Navajo Unit - San Juan River New Mexico, Colorado, 

Utah (USBR 2006). Therefore, there would be no additional effects from stream flow depletion to 

Colorado pikeminnow resulting from the proposed action beyond those previously disclosed and analyzed 

in the Navajo Reservoir Operations Navajo Unit - San Juan River New Mexico, Colorado, Utah FEIS. 

The power plant would result in the deposition of incremental quantities mercury and selenium in the San 

Juan River. Pollutant concentrations are likely to vary depending on location, prevailing winds and 

rainfall and other factors. A more detailed discussion is provided in Section 6.3.1 under Surface Water 
Biological Assessment of the Desert Rock Energy Project, April 2007 43

Quality Effects. The additive effect of mercury and selenium deposition to existing concentrations in the 

San Juan River will result in minor impacts to surface water quality. However, these impacts are not 

expected to exceed AWQC standards for the protection aquatic wildlife. Existing selenium concentrations 

in the San Juan River and Morgan Lake have been linked to a low to moderate occurrence of reproductive 

failure in endangered fish species given selenium concentrations found in tissues and diets (USFWS 

2005). The cumulative impact to surface water quality from the deposition of mercury and selenium may 

result in adverse effects to the reproductive success of this species. 

Recommended Conservation / Mitigation Measures: 

• Implementation of a Storm Water Pollution Prevention Plan for all construction activities with 

potential to discharge of sediment into the San Juan River. This includes project components that 

are adjacent to the San Juan River, as well as those components constructed away from the San 

Juan River, but with potential for runoff to flow into the San Juan River. 

• A Hazardous Materials Handling and Response Plan would be developed and implemented for all 

proposed project components. 

Determination of Effect: The proposed action may affect, is likely to adversely affect Colorado 

pikeminnow. 

6.6.5 Razorback sucker (Xyrauchen texanus) 

Status: Federal Endangered with Designated Critical Habitat 

Distribution and Habitat: This species is found in backwaters, flooded bottomlands, pools, side 

channels and other slower moving river habitats below 6,000 feet elevation. Razor back suckers have 

historically been found in large rivers near strong currents and once inhabited the Colorado, Gila, Salt, 

Verde, and San Pedro rivers. Razorback suckers spawn prior to spring run-off in late March or early April 

over sand or gravel substrates (BISONM 2006). 

Potential to Occur in the Project Area: On the Navajo Nation, this species has potential to occur 

within the San Juan River, upstream from Lake Powell. However, the only occurrences of wild razorback 

sucker from the San Juan River are from Bluff, Utah (RM 85) and occurred in 1978 and the late 1980’s 

Razorback sucker has never been documented from and is not expected to occur in the Chaco River, as 

this species requires perennial bodies of water. 

The razorback sucker can be found in the San Juan River from Farmington to Lake Powell. Adult 

razorback suckers typically occur in deep areas of the river such as pool habitats and also large 

backwaters. Razorbacks feed primarily on algae, plant debris and a variety of invertebrates. Initiated in 

1994, razorbacks were reintroduced from rearing facilities to the San Juan River. It has continued 

annually through 2006. The reintroduced populations are reproducing based on the belief there are no 

more wild razorback suckers left in the system collections of larval and juvenile razorback suckers from 

the river as recent as 2006 (Brandenberg et al. 2002, Dale Ryden, USFWS, pers. comm. 2006). 

Razorback spawning has been documented near Aneth, Utah at RM 100.2 and near RM 152.2 (Dale 

Ryden, USFWS, pers. comm. 2006). During fall 2006 electrofishing surveys conducted on the San Juan 

River 110 razorbacks were collected from Farmington to the Four Corners area (Dale Ryden, USFWS, 

pers comm. 2006). As stated above, it is hypothesized that the survivability of these stocked fish can be 

attributed to the success non-native catfish removal has had in reducing predation on native fishes 

including larval and juvenile razorback suckers. 
Biological Assessment of the Desert Rock Energy Project, April 2007 44

Stocked razorback suckers use a variety of habitats. During the winter, they tend to occupy highly diverse 

aquatic habitats while in the early summer they’re more commonly found in areas of inundated 

vegetation. During the summer and extending into the fall they are found most often in fast run habitats. 

Similar to what was described above under the Colorado pikeminnow section, efforts were initiated to 

augment populations of razorback suckers in the San Juan River through stocking practices first initiated 

in 1999. This augmentation program has been extended through 2011 (Ryden and McAda 2003). The 

goal of this program is to establish an adult population of 5,800 razorback sucker in the San Juan River. 

Several “grow out” ponds near the San Juan River have been established to meet the stocking needs. As 

described above under the Colorado pikeminnow, additional recovery efforts include mimicking the 

natural hydrograph through the designated critical habitat reach, monitoring stocking success, control of 

non-native fish, habitat monitoring and removal of fish passage barriers. 

As discussed above, removal of the Cudei Diversion, construction of free passage at the Hogback 

Diversion and construction of a selective fish passage at the PNM weir have already been completed. 

Razorback suckers were documented using the Nenahezad fish passage at the PNM weir in 2003 (Lapahie 

2004). 

Critical habitat for the razorback sucker has been designated from Neskahai Canyon (RM 10) to the 

Hogback Diversion (RM 160). The entire stretch of the San Juan River that crosses the project area is 

included in the razorback sucker critical habitat designation. Razorback sucker is expected to be present 

within this section of river to include the section of river within the project area. 

Project Effects to Razorback Sucker: The proposed Transmission Line Segment D would span 

razorback sucker critical habitat. Construction of the proposed alignment may result in 2 tower sites 

being placed within the 100-year floodplain of the San Juan River resulting in permanent disturbance to 

approximately 1.8-acres of upland habitats. The 100-year floodplain is considered part of the critical 

habitat designation. Construction of the Transmission Line Segment D would not result in adverse effects 

to primary constituent elements within designated critical habitat following the implementation of 

mitigation measures. No construction activities would occur within or adjacent to the San Juan River 

stream channel for the proposed action. 

Ground disturbance associated with construction within the floodplain has the potential to increase 

sediments reaching the San Juan River. Additionally, accidental fuel, lubrication or other hazardous 

material spills in the construction zone, depending upon the size, has potential to reach the San Juan River 

and adversely impact localized fisheries and/or downstream habitats such as nursery backwaters. 

Water depletion for the operation of the proposed power plant and associated infrastructure and mining 

operations would have no effect to razorback sucker or critical habitat. The average annual water 

consumption demand of the proposed Desert Rock Power Plant is estimated at 4,950 ac/ft per year, or 

3,070 gallons per minute (gpm), of continuous flow for a period of 40 consecutive years. Groundwater is 

proposed to be pumped from the Morrison aquifer to meet this need (URS 2007). Given the distance 

between the water well field and San Juan River no effects to stream flows are expected from the 

extraction of 4,950 ac/ft per year from the Morrison Aquifer (Brooks and Miller 2007). 

Effects from water depletion to razorback sucker under BNCC’s consumptive San Juan River water rights 

have been evaluated and documented in the Final Environmental Impact Statement Navajo Reservoir 

Operations Navajo Unit - San Juan River New Mexico, Colorado, Utah (USBR 2006). Therefore, there 

would be no additional effects from stream flow depletion to razorback sucker resulting from the 
Biological Assessment of the Desert Rock Energy Project, April 2007 45

proposed action beyond those previously disclosed and analyzed in the Navajo Reservoir Operations 

Navajo Unit - San Juan River New Mexico, Colorado, Utah FEIS. 

The power plant would result in the deposition of incremental quantities mercury and selenium in the San 

Juan River. Pollutant concentrations are likely to vary depending on location, prevailing winds and 

rainfall and other factors. A more detailed discussion is provided in Section 6.3.1 under Surface Water 

Quality Effects. The additive effect of mercury and selenium deposition to existing concentrations in the 

San Juan River will result in minor impacts to surface water quality. However, these impacts are not 

expected to exceed AWQC standards for the protection aquatic wildlife. Existing selenium concentrations 

in the San Juan River and Morgan Lake have been linked to a low to moderate occurrence of reproductive 

failure in endangered fish species given selenium concentrations found in tissues and diets (USFWS 

2005). The cumulative impact to surface water quality from the deposition of mercury and selenium may 

result in adverse effects to the reproductive success of this species. 

Recommended Conservation / Mitigation Measures: 

• Implementation of a Storm Water Pollution Prevention Plan for all construction activities with 

potential to discharge of sediment into the San Juan River. This includes project components that 

are adjacent to the San Juan River, as well as those components constructed away from the San 

Juan River, but with potential for runoff to flow into the San Juan River. 

• A Hazardous Materials Handling and Response Plan would be developed and implemented for all 

proposed project components. 

Determination of Effect: The proposed action may affect, is likely to adversely affect razorback sucker. 

6.6.6 Mancos milkvetch (Astragalus humillimus) 

Status: Federally Endangered 

Distribution and Habitat: Mancos milkvetch (Astragalus humillimus) is a diminutive, tufted perennial 

with leaves that have spines along the central veins. The plant flowers in late April to early May 

producing pale lavender to dark purple blooms. This species occurs at elevations ranging from 5,000 to 

6,000 ft, within cracks or eroded depressions in sandstone ledges and mesa tops in the Point Lookout 

sandstone. It is currently limited to 10 populations in New Mexico and 3 populations in Colorado. The 

sites range from San Juan County, New Mexico to Montezuma County in Colorado and from Mancos 

Canyon, Colorado southward just past the San Juan River in San Juan County, New Mexico. Plants often 

found associated with Mancos milkvetch include mountain mahogany, cliff rose, Fendler’s bladderpod, 

and Cottam’s milkvetch. 

Potential to Occur in the Project Area: On the Navajo Nation, Mancos milkvetch populations are 

known to extend eastward from Palmer Mesa to the Hogback area and south of the San Juan River, to the 

Hogback east of Little Water. Known populations of Mancos milkvetch occur about 10 miles southwest 

of Area IV North (approximately 15 miles southwest of Farmington, New Mexico) outside the project 

area. 

There are historical records of Mancos milkvetch occuring at the Hogback exposure just south of Navajo 

Route 13 where the Transmission Line approaches within 500 feet. Potential Mancos milkvetch habitat is 

present along the proposed transmission line corridor just north of U.S. Highway 64 along the Hogback. 

Marginal potential habitat occurs along the proposed corridor where it crosses the Hogback (Ecosphere 
Biological Assessment of the Desert Rock Energy Project, April 2007 46

2005a). Potential habitat was also recorded along the proposed Desert Rock Energy Project Alternative 

Water Well Field and Utility Corridor (URS 2007). No Mancos milkvetch populations were located 

within the proposed action area. 

Project Effects to Mancos Milkvetch: The action area offers potential, but unoccupied habitat for this 

species. This species was not observed within the proposed action area during surveys (Ecosphere 

2005a). However, prolonged drought conditions in the area may have precluded germination over the 

past several years. 

Human presence has the potential to disturb vegetation in the action area, particularly in areas where 

humans travel beyond the boundaries of established roads, corridors, rights-of-way, or facilities. Potential 

effects would be from suitable habitat loss and modification. Dormant seedbeds may be adversely 

impacted by construction activities. These potential impacts would be insignificant and discountable. 

Recommended Conservation / Mitigation Measures: 

• Implementation of a Storm Water Pollution Prevention Plan for all construction activities with 

potential to discharge sediment in areas of suitable Mancos milkvetch habitat. This should 

include even small-scale projects. 

• In areas of potential Mancos milkvetch habitat, pre-construction surveys are recommended for all 

potentially disruptive activities and for all ground disturbing activities. This includes all 

construction and maintenance activities, or any activity requiring human presence outside of 

developed. Surveys should include a minimum of a 200-ft buffer around the areas that have 

potential to be disturbed. The recommended survey period is during the flowering period (April 

to early May); however, surveys can be conducted by experienced botanists year-round. If 

individuals are encountered during surveys, construction plans should be altered to minimize or 

eliminate disturbance. 

• Human activity in portions of the project area where Mancos milkvetch have potential to occur 

should be minimized. Workers associated with the Desert Rock project would limit their 

activities to established construction and maintenance areas, roads and walkways. 

Determination of Effect: The proposed action may affect, is not likely to adversely affect Mancos 

milkvetch. 

6.6.7 Mesa Verde cactus (Sclerocactus mesae-verdae) 

Status: Federally Threatened 

Distribution and Habitat: Mesa Verde cactus is distinguished from other cacti of the Sclerocactus

genus by an almost total lack of central spines. This species has gray-green to pale green stems that are 

depressed-globose to oval in shape (Heil and Porter 1994) and typically produces yellowish-cream 

flowers from late April to early May, although extreme southern populations tend to produce pink 

flowers. Mesa Verde cactus is typically is found on or near clay hills at elevations ranging from 4,900-

5,500 feet associated with the Fruitland and Mancos Shale geological formations (Heil and Porter 1994). 

The western extent of the Mancos and Fruitland Formations are located in western San Juan County, New 

Mexico and southwestern Montezuma County, Colorado. The range of Mesa Verde cactus is roughly 

defined on the northern boundary by Cortez, Colorado, Sheep Springs, New Mexico on the southern 

boundary, the Chuska and Carrizo Mountains in New Mexico along the western border, and Kirtland, 
Biological Assessment of the Desert Rock Energy Project, April 2007 47

New Mexico and the Chaco River along the eastern boundary. Plants often found associated with Mesa 

Verde cactus often include mat saltbush, prickly pear cactus, shadscale, and frankenia (Heil and Porter 

1994). 

Potential to Occur in the Project Area: This species occurs along Transmission Line D north of San 

Juan River, where approximately 1000-1200 acres of good habitat occurs along the existing power 

transmission line. The proposed action area contains one general population of Mesa Verde cactus north 

of the San Juan River, west of the Hogback and south of the proposed NTP utility line. This population 

lies in close proximity to Segment D of the preferred transmission line alignment. In surveys conducted 

during the summer of 2006, this population was reported to contain 78 dead individuals and 42 live 

individuals (Ecosphere unpublished data). 

Because of recent drought conditions and concurrent pressures of insect herbivory within the range of 

Mesa Verde cactus, many known populations have suffered significant reductions, and in some cases 

possible extirpation of individual populations. Because of the slow growth rates and cryptic habits of 

seedlings, the results of these effects on Mesa Verde cacti will not become evident for several years after 

better climatic conditions return. It is likely that seeds of the Mesa Verde cacti survive in the seed bank 

present in many of these sites, awaiting the return of more favorable conditions. As unoccupied but 

potential habitat may host ecologically important seed banks, appropriate conservation measures should 

be applied to these areas as well. 

Project Effects to Mesa Verde Cactus: This species occurs along the proposed transmission line 

alignment north of the San Juan River in close proximity to Segment D. During construction of tower 

structures, wire-pulling and wire-splicing, human and vehicular activity within the proposed transmission 

line alignment would potentially result in cacti damage or mortality where the populations occur within 

the proposed right-of-way or access roads. Blading and leveling of tower sites could potentially kill or 

severely damage plants at those locations either by vehicle compression, soil removal, or plants buried 

under spoils. Vehicles and heavy equipment traveling along the proposed corridor or access roads could 

crush plants. 

Human or vehicular activity outside the proposed right-of-way or access roads may trample individuals or 

disrupt soils. Though potential impacts would be greatest during construction, human or vehicular 

activity during transmission line maintenance would potentially trample individuals or disrupt soils. 

Temporary soil disturbance may negatively impact seed sources if dead individuals are damaged or 

removed. Seedbed disturbance in population areas, and areas that may not currently support live 

individuals, could potentially result in a loss of seed viability and decrease the success of recolonization. 

Disturbed soils would be subject to greater erosion which could impact individuals by exposing roots or 

by smothering stems. Construction activities would disturb and alter potential habitat, which may affect 

the ability of the species to colonize those areas. During revegetation efforts, further disturbance to soil 

structure could accelerate erosion processes, which could impact the species by uprooting of individuals 

during storm events. 

The enlargement of the existing transmission line right-of-way with the addition of the proposed action 

could encourage increased public use of the corridor which would result in further disruption of soils and 

the potential for plant mortality within or areas adjacent to the right-of-way. 

Restrictive fencing or flagging of existing populations for extended periods could attract the public and 

result in illegal collection of specimens. 
Biological Assessment of the Desert Rock Energy Project, April 2007 48

Recommended Conservation / Mitigation Measures: 

Because of the potential impacts to this species as a result of the proposed project, specific conservation 

and mitigation measures for Mesa Verde cactus have been developed with the assistance of USFWS, the 

NNDFW, and other appropriate agencies. Recommended conservation measures are intended to closely 

conform with those developed for the NTP alignment during the course of Section 7 consultations 

completed for that project. The goal of these measures is to avoid or minimize all types of disturbance, 

direct or indirect, to Mesa Verde cactus and habitat. 

The conservation/mitigation measures described below apply to all areas where Mesa Verde cacti are 

known to occur and individual plants or populations have been observed. Also included are measures to 

protect suitable but unoccupied habitats for this cactus. Desert Rock Energy LLC and their contractors 

will strictly comply with all stipulations of the grant of easement issued by the BIA for the project 

throughout the term of the grant, as well as the procedures and stipulations identified in the project plan of 

development (POD). 

• Intensive pedestrian surveys for Mesa Verde cacti were performed in May of 2006. All Mesa 

Verde cacti and associated habitat that could potentially be affected by construction, operation, or 

maintenance of the transmission line was documented. All areas that may be affected (directly or 

indirectly) by construction, operation, or maintenance of the line or access roads, within the 250-

foot right-of-way and access roads outside the right-of-way will be resurveyed prior to 

construction activities to develop a pre-engineering map which will include all cacti locations 

from previous surveys. Unoccupied habitat will be classified in terms of quality based on 

substrate suitability, the degree to which suitable substrate is fragmented or isolated, previous 

presence of cacti (based on NNHP records and the 2006 surveys), and proximity to occupied 

habitat. 

• Based on the results of the 2006 surveys and pre-engineering surveys, a detailed Mesa Verde 

Cactus Construction Plan will be developed for the purposes of avoiding cacti and minimizing 

disturbance of habitat to the greatest extent practicable. The construction plan will include a map 

of all cacti identified through the Spring 2006 surveys, pre-engineering surveys, habitat 

classification by quality, and all construction work areas. The construction plan will be submitted 

to the USFWS, NNDFW, and the Bureau of Indian Affairs for review. In order to discourage the 

illegal harvesting of cacti, the locations of cacti will be kept confidential and no universal 

transverse mercator coordinates will be included in the final reports. Project Construction 

Inspectors and biological monitor(s) will be the only individuals with detailed cacti location 

information. All agency comments will be addressed and incorporated into the plan, as 

appropriate, prior to construction. The plan, without the maps of specific cacti locations, will be 

included in the project POD and adherence to the recommendations included therein will be a 

requirement of the construction contractor. 

• Construction areas, including tower sites and spur roads, will be located in coordination with 

project engineers and resource specialists so as to avoid individual cacti and habitat identified 

during the surveys. Wire-pulling and wire-splicing sites and materials staging areas will be 

evaluated for the presence of individual cacti prior to the clearing of any vegetation necessary in 

order to store equipment on site. Placement of these areas will be within, or will be as near as 

practicable, to existing roadways and/or heavily used areas. The siting of these areas also will 

take into consideration indirect effects from operation and maintenance (e.g., long-term 

utilization of access roads in areas where cacti are known to occur) as well as effects related to 
Biological Assessment of the Desert Rock Energy Project, April 2007 49

potential increase of access by off-road/highway vehicles. The pre-engineering surveys will 

determine the level of impact on cacti or their habitat in areas of conventional access. 

• To the extent practicable, the placement of access roads will minimize disturbance to Mesa Verde 

cactus habitat. The approximate locations of overland spur access roads will be included as part 

of the detailed maps included in the POD. The locations of access roads will be further refined 

once final engineering has been completed and the exact locations of the tower sites are 

determined. The edges of the access roads will be flagged in the field and to the extent 

practicable, will take advantage of existing disturbance, slope, and topography. Access roads will 

not be proposed in any area known to contain individual Mesa Verde cacti based on the results of 

both the 2006 surveys and pre-construction surveys. To the extent possible, access roads will be 

sited no closer than 50 feet from a known individual cactus location. 

• Overland spurs will not be bladed and construction personnel will be advised to follow existing 

tire tracks within the designated area and minimize their trips along these spurs to the extent 

possible in order to reduce disturbance. When construction is complete, all tower sites and spur 

roads will be hand-raked to remove tire tracks. An emphasis will be placed on obscuring access 

points at intersections with paved and improved dirt roads and re-creating the topography and 

natural barriers (e.g., washes). Reclamation techniques will be specifically designed to address 

site-specific soil properties and the potential for long-term erosion. 

• Pre-construction surveys for Mesa Verde cacti will be conducted in the spring of the year 

preceding the initiation of construction to identify any new areas of cacti. The locations of any 

additional cacti identified during pre-construction surveys will be added to the project maps 

developed for the POD. Appropriate mitigation will be developed and reviewed with the Bureau 

of Indian Affairs, and other applicable agencies, and included in the POD. 

• A worker education and awareness program for Mesa Verde cacti will be developed and 

presented to all personnel that will be on site during pre-construction surveying and construction. 

The program will include information on the legal and biological status of Mesa Verde cactus, the 

importance of habitat, the occurrence of cactus and unoccupied habitat in the study area, 

conservation measures, fines and penalties for damaging or removing cacti, and reporting 

procedures to be used if cacti not previously identified are discovered or disturbed cacti are 

discovered. A simple pamphlet or card summarizing critical information for avoiding cactus and 

minimizing effects on habitat will be provided to all field personnel. 

• Qualified biologists will be on site to monitor avoidance of cacti and habitat during all 

construction-related activities, including the initial delineation of construction exclusion areas 

(e.g., fenced and flagged areas). All sites where Mesa Verde cacti are present will be monitored 

daily. Construction activity within 200 feet of a cactus site will be monitored continuously during 

construction activity. Any disturbance to cactus or habitat outside the construction zone will be 

reported immediately by the biological monitor to the Construction Inspection Contractor who 

will report to the BIA and the NNFWD. A written account including a map, the extent of the 

disturbance, the number of cacti and/or quantity of habitat disturbed, and the circumstances 

surrounding the disturbance will be submitted to the Bureau of Indian Affairs within 48 hours. 

The incident reporting procedures for all construction activity is part of the project POD. 

• Access roads and tower sites in areas where Mesa Verde cacti are present will be enclosed with 

construction fencing. Fencing along access roads will extend 200 feet in both directions beyond 

the limits of areas that contain cacti or designated suitable habitat. Any cacti located within the 
Biological Assessment of the Desert Rock Energy Project, April 2007 50

right-of-way will be enclosed with construction fencing including, where possible, a buffer radius 

of 50 feet around the cacti. All project personnel will be instructed that their activities must be 

confined to the designated construction area. All construction fencing will be inspected daily by 

the on-site biologist and maintained in a functional capacity by the contractor. 

• All traffic will be restricted to the right-of-way, designated work areas, and authorized access 

roads. Overland spur roads will be used in areas to minimize surface disturbance and will be 

staked or flagged in the field. Cross-country travel will be strictly prohibited. 

• The pneumatic cleaning of construction equipment will be required before it is permitted on the 

right-of-way, as well as when equipment is moved from an area where noxious plant species are 

known to be present. Water shall not be used to clean equipment since it may provide moisture 

for germination of noxious weed seed that may be present. 

• Because of the delicate nature of soil structure in areas that support Mesa Verde cacti, no postconstruction reseeding will be implemented. Such soils are typically fine-grained, possess a low 

cohesion and in-place density, and are highly subject to erosion. Disturbance to soil structure 

during revegetation efforts conducted in these types of soils can accelerate erosion processes, 

which are known to be detrimental to Mesa Verde cacti. Reseeding would establish plants in 

Mesa Verde cactus habitat, in some instances where there is currently minimal vegetation that 

would compete with the cacti for water and other resources. A restoration plan for all areas of 

disturbance will be included in the POD. 

• Routine post-construction inspections of the line in Mesa Verde cactus habitat will be performed 

using aircraft. For minor maintenance or repair of structures or line that may be required, access 

will be accomplished by helicopter. If extensive repairs are required, all stipulations governing 

the placement and restoration of access routes covered in this document will be required. Surveys 

for Mesa Verde cactus will be required prior to any ground disturbing activities for maintenance. 

Surveys performed will be valid for three years. 

• Individual Mesa Verde cacti that cannot be avoided during the construction process will be 

transplanted in cooperation with the NNDFW. Transplanted cacti will be monitored for a 

minimum of 5 years. Desert Rock Energy LLC will provide funding for the annual monitoring 

and monitoring report. 

• Desert Rock Energy LLC will monitor the Mesa Verde cactus population for a five year period in 

the vicinity of where the DREP connects to the Navajo Transmission Project. 

• Locked gates will be installed at strategic locations to restrict unauthorized vehicle access to 

protect Mesa Verde cacti along the right-of-way. Strategic locations are those areas where a gate 

can be placed into a topographic feature that cannot be crossed by vehicles. Signs will be placed 

at intersections of the access road with other roads to discourage vehicular traffic along the rightof-way. They will alert people to the sensitivity of the area. 

• Desert Rock LLC will develop a comprehensive weed management plan that addresses the 

management of exotic species for a period of time post construction (preferably at least 5 years). 

Determination of Effect: The proposed action may affect, is likely to adversely affect Mesa Verde 

cactus. 
Biological Assessment of the Desert Rock Energy Project, April 2007 51

6.6.3 Yellow-billed cuckoo (Coccyzus americanus occidentalis) 

Status: Federal Candidate 

Distribution and Habitat: Yellow-billed cuckoos are neo-tropical migrants that winter primarily in 

South America. Suitable habitat for yellow-billed cuckoo is limited to narrow, and often widely separated, 

riparian cottonwood-willow galleries, as well as salt cedar (USFWS 2001). Dense understory foliage 

appears to be an important factor in nest site selection, whereas cottonwood trees are an important 

foraging habitat for the yellow-billed cuckoo. The species is usually found at elevations below 6,600 feet 

and has been documented in southern and central and extreme northeast Arizona (USFWS 2001). 

Historically, the yellow-billed cuckoo has been documented as occurring along the San Juan River from 

Navajo Reservoir to the Arizona state line (Travis 2002). 

Potential to Occur in the Project Area: Breeding habitat is typically characterized by riparian 

vegetation that has a dense overstory of mature cottonwood trees. As such, potential breeding habitat for 

yellow-billed cuckoo is present at the Transmission Line Segment D crossing along the San Juan River, 

and along the northern margin of Morgan Lake. Although the Chaco River supports riparian vegetation, 

preliminary examination of this habitat by Ecosphere in 2006 indicated that the density and extent of this 

habitat was not likely to support yellow-billed cuckoo. 

BLM/FFO surveys between 2002 and 2003 recorded this species at five river tracts between the Hogback 

and Bloomfield, New Mexico. In 2002, a yellow-billed cuckoo was recorded at the BLM Bradshaw Tract 

approximately 2 miles east of the proposed Transmission Line San Juan River crossing. A yellow-billed 

cuckoo was recorded during 2003 surveys of the BLM Wheeler Tract located approximately 3⁄4 mile from 

the proposed Transmission Line river crossing. The BLM/FFO has not conducted formal surveys for this 

species since 2004 (Wegener BLM/FFO, pers. comm. 2006). There are no documented occurrences of 

yellow-billed cuckoo nesting on the San Juan River. 

In June and August 2006, species specific surveys were conducted for yellow-billed cuckoo along the San 

Juan River in the project area using draft USGS guidelines (Ecosphere unpublished). No individuals 

were detected during these surveys.

Project Effects to Yellow-billed cuckoo: Potential habitat for the yellow-billed cuckoo is limited to 

small patches of native riparian (cottonwood and willow) and mixed native-exotic (Russian 

olive/tamarisk, cottonwood and willow) adjacent to the Transmission Line Segment D crossing of the San 

Juan River, along the northern margin of Morgan Lake and in very small scattered patches where 

overstory cottonwoods are present along the Chaco River. There would be no removal of potential 

habitat in these areas for the proposed action. 

Potential impacts to this species would be limited to noise and human activity in proximity to occupied 

habitats. Increases in noise and human activity would likely result in short-term temporary dispersal or 

avoidance of the area. No construction activities within 1⁄4-mile of suitable habitats during breeding 

season, May through August, would minimize or eliminate this potential impact. These impacts would be 

insignificant and discountable. 

Operation of the proposed power plant and associated infrastructure, water well field and mining 

operations would have no effect to yellow-billed cuckoos or potential habitats. 
Biological Assessment of the Desert Rock Energy Project, April 2007 52

Recommended Conservation / Mitigation Measures: 

• Timing restrictions for construction of transmission towers and stringing of conduit lines, as well 

as other construction and maintenance activities within and above the San Juan River floodplain 

and within 1⁄4 mile of the Chaco River. Work should not be conducted between May 1 and 

August 30 to avoid disturbance.

• Should clearing of riparian vegetation in areas of suitable cuckoo habitat be necessary, Desert 

Rock Energy LLC in coordination with the Navajo Natural Heritage Program and the USFWS, 

will develop a compensatory mitigation plan to offset the potential loss of habitat.

• Because yellow-billed cuckoo habitat along the Chaco River was not subject to protocol surveys 

in 2006 in all survey periods, the Chaco River should be resurveyed for cuckoo if habitat 

conditions change over the course of project development and construction. 

7.0 Summary of Determinations of Effect 

This section summarizes the effect determination for each of the ESA listed species with potential to 

occur in the project area. Also addressed in this section are the potential cumulative effects that may 

result from the proposed action, as well as interrelated projects and reasonable foreseeable developments 

that may occur in or near the Desert Rock project area. 

7.1 Determinations of Effects for ESA Listed Species 

Determinations of effect of have been assigned for all species 9 federally listed under ESA with potential 

to occur in the Desert Rock Energy Project area and critical habitat present in the analysis area. 

Determinations of effect were based on evaluating the potential impacts of the proposed action if the 

recommended conservation and mitigation measures are followed. Table 7-1 summarizes the effect 

determination of the proposed action on federally listed threatened and endangered candidate species. 

Table 7-1. Summary of the Determinations of Effect on Federally Listed Species. 

SPECIES STATUS DETERMINATION OF EFFECT 

MAMMALS

Black-footed ferret E No Effect 

BIRDS 

Bald eagle T May Affect, Likely to Adversely Affect 

Mexican spotted owl T No Effect 

Southwestern willow flycatcher E May Affect, Not Likely to Adversely Affect 

FISH 

Colorado pikeminnow E May Affect, Likely to Adversely Affect 
Biological Assessment of the Desert Rock Energy Project, April 2007 53

Colorado pikeminnow critical habitat No adverse modification 

Razorback sucker E May Affect, Likely to Adversely Affect 

Razorback sucker critical habitat No adverse modification 

PLANTS 

Knowlton’s cactus E No Effect 

Mancos milkvetch E May Affect, Not Likely to Adversely Affect 

Mesa Verde cactus T May Affect, Likely to Adversely Affect 

7.2 Cumulative Effects 

Ongoing and future activities on lands within the analysis area may include agricultural development 

including farming and ranching by members of the Navajo Nation. In addition, Navajo Agricultural 

Products Industry (NAPI), which is located immediately southwest of the proposed project area, will 

continue to develop and operate for the foreseeable future. Agricultural development has the potential to 

exacerbate air and water pollution in the project area and vicinity through the use of conventional 

pesticides and herbicides, as well as from repeated ground disturbances that contribute to generation of 

airborne particulates. In addition, livestock can contribute to ground disturbance by compacting soil and 

damaging cryptogamic soil crusts. 

As proposed, the Desert Rock Power Plant site would be constructed in close proximity to two existing 

power plants, the Arizona Public Service Four Corners Generating Station and the San Juan Power Plant. 

Addition of the Desert Rock Power Plant has the potential to increase all sources of disturbance discussed 

in previous sections of this documents. Dine Power Authority, an enterprise of the Navajo Nation, would 

be the developer of the NTP. The NTP would add 470 miles of 500kV alternating current transmission 

capability from the Four Corners area to the Las Vegas area, with an interconnection point north of 

Flagstaff to allow access to the metropolitan Phoenix market. 

Although there are no oil or natural gas wells in the proposed project area, the surrounding areas are 

subject to extensive oil and natural gas production. In 2003, it was estimated that there were over 18,000 

gas wells within the New Mexico portion of the San Juan Basin, which accounted for over two-thirds of 

the total gas production for the State of New Mexico (USDI Bureau of Land Management 2003). 

Operation of natural gas wells and refineries represent a notable source of air pollution in the project area 

and vicinity, which may exacerbate the impacts of air pollutants generated by the proposed Desert Rock 

project. Western Oil and Gas has proposed approximately 600 natural gas wells in eastern Burnham 

Chapter extending north into Upper Fruitland and Nenahnezad/San Juan Chapters. An EIS is currently 

being prepared for the Phoenix Expansion Project, which would expand the Transwestern Pipeline 

Company’s natural gas pipeline system by approximately 260 miles from its mainline in Yavapai, 

County, Arizona to delivery points in the Phoenix metropolitan area market. As part of the overall project, 

Transwestern plans to build approximately 25 miles of pipeline looping parallel to its existing San Juan 

Lateral, in San Juan County. The San Juan Lateral extends from San Juan County, New Mexico, to 

connect with Transwestern’s mainline in McKinley County, New Mexico, and is located approximately 

15 miles or further from the analysis area. 

Development of the existing and future projects would result in continued loss and alteration of wildlife 

habitat, including fragmentation; intentional and unintentional harassment of wildlife; invasion of non-
Biological Assessment of the Desert Rock Energy Project, April 2007 54

native vegetation; intentional and unintentional mortalities of wildlife from exposure to contaminants, 

depletion of water resources, collisions with vehicles, increases in legal or illegal harvest of game and 

non-game species, electrocution/collusion with overhead electrical transmission lines; increases in air and 

water pollution that directly and indirectly effect plants and animals. Further, increases in human activity 

to previously undisturbed habitats inevitably results in adverse impacts to vegetative communities and 

wildlife. The cumulative effects of these incursions are difficult to accurately quantify as the ultimate 

effects are dependant upon the species potentially present in the area, the timing of the human activity, the 

nature of the activity, the duration of the activity, and what is happening in adjacent habitats at the time of 

proposed disturbance. 

Further, some species of wildlife are more suited to adapt to rapid environmental change, while other 

species may be seasonally or permanently displaced from otherwise favorable habitat. Residential and 

industrial development in the San Juan Basin may have already influenced the occurrence, distribution, 

and abundance of wildlife within and near the proposed DREP analysis area. The degree and magnitude 

of wildlife impacts that could be cumulative as a result of developing the proposed action is generally 

considered a minor cumulative effect. The cumulative loss of habitat from the proposed project is not a 

significant loss of habitat because of the abundance of similar habitat in the region and across the Navajo 

Nation. However, increases in traffic along existing regional and planned local road networks 

cumulatively would have a moderate or likely noticeable, adverse cumulative impact on wildlife as a 

result of road killed animals in the San Juan Basin. According to the cumulative Class I increment air 

modeling analysis included in Section 4.5 of the ENSR Report Desert Rock Energy Facility Application 

for Prevention of Significant Deterioration Permit – Class I Area Modeling Update, January 2006, 

cumulative air quality impacts of the proposed project will be negative (overall lower emissions in the 

Four Corners region) due to increased emission controls occurring at the Four Corners Power Plant and at 

the San Juan Generating Station. If this is indeed the case, then biological resources would not be subject 

to cumulatively significant adverse impacts. 

There would be a minor loss of available habitat for bald eagle with the addition of a transmission 

corridor across the San Juan River that would periodically inhibit eagle foraging and travel flight patterns 

along the river corridor. This impact is considered small as the proposed transmission would parallel an 

existing transmission line, thereby widening an existing obstruction to eagle flight along the river. It is 

not known whether the addition of a second transmission line would serve to assist eagles, raptors or 

other birds avoid collusions with the lines due to increased visibility. An unknown number of Mesa Verde 

cactus may also be damaged or killed with the construction and maintenance of Segment D of the 

proposed transmission line and the Navajo Transmission Project (NTP). A mitigation plan has been 

prepared for NTP to minimize impacts on the Mesa Verde cactus. Construction and maintenance of 

transmission access roads and the construction footprint of tower locations would result in some 

permanent loss of potentially viable habitat and/or seed bank for Mesa Verde cactus. 

Wildlife exposed to mercury via their diet may be subject to reproductive failure, immune system 

impairment, behavioral aberrations, motor dysfunctions, or even direct toxicity. Most at risk are those 

animals at upper trophic levels that feed on fish, or on other animals that feed on fish. While little reliable 

information is available, there are no known instances of mercury intoxication of wildlife in New Mexico. 

Assessment of the impact of mercury on wildlife is difficult however, since some of the symptoms 

associated with chronic mercury poisoning may not be immediately apparent, resulting in reduced 

functionality, inappropriate breeding behavior, or early mortality by some other mechanism, e.g. impaired 

predator evasion. Minor increases in mercury and selenium, and other potentially toxic elements, 

reaching the San Juan River from air pollution deposition may contribute to adversely impacting 

razorback sucker and Colorado pikeminnow reproductive success and recovery efforts. In addition, 

mercury that is sorbed to sediment is still available to methylating bacteria when carried into the anoxic 

zones of river beds and reservoirs where methylation occurs. 
Biological Assessment of the Desert Rock Energy Project, April 2007 55

Depending on the mitigation measures applied and the degree that measures are enforced under the 

jurisdictional authority of projects currently being implemented, and for those proposed in the future, the 

magnitude of cumulative adverse impacts can only be incrementally minimized. 

 

7.3 Reasonable Foreseeable Developments 

As designed, the preferred alternative for the proposed access road would spur off of the existing 

Burnham Road. However, feasibility of this alternative is dependent on re-routing Burnham Road. 

While this road construction would be permitted under BHP’s existing mine lease, it would require 

substantial new ground disturbance that has not been addressed in detail by this Biological Assessment or 

by the DEIS prepared for the Desert Rock project. 
Biological Assessment of the Desert Rock Energy Project, April 2007 56

8.0 Biological Assessment Preparers 

Joey Herring B.S. Environmental Biology 

Erin Powell, Wildlife Biologist M.S., Ph.D. – Wildlife Ecology 

Lynn Wickersham, Wildlife Biologist M.S. – Biology 

Mike Fitzgerald, Environmental Scientist B.A. – Environmental Studies 

Sandy Friedley, Botanist M.S. - Botany 
Biological Assessment of the Desert Rock Energy Project, April 2007 57

9.0 Literature Cited and References 

APLIC. Avian Power Line Interaction Committee. Suggested Practices For Raptor Protection On Power 

Lines: The State of the Art in 1996. Edison Electric Institute and Raptor Research Foundation. 

_____. Avian Power Line Interaction Committee. 2005. Avian Protection Plan Guidelines. The Edison 

Electric Institute’s Avian Power Line Interaction Committee and U.S. Fish and Wildlife Service. 

Belnap, J. and D. A. Gillette. 1997. Disturbance of biological soil crusts: impacts on potential wind 

erodibility of sandy desert soils in southeastern Utah. National Biological Service, 2282 S. 

Resource Blvd., Moab, UT 

BISONM (Biotic Information System of New Mexico). 2006. Species Reports. Available online at: 

http://www.bison-m.org/

BHP Billiton. 2004. Navajo Coal Company Navajo Mine Proposal for Phase II Release on 1,034 Acres: 

Report of Vegetation Sampling and Data Analysis Plus Sedimentation Studies for Phase II Bond 

Release Areas. BHP Billiton Navajo Coal Company: Fruitland, New Mexico. 

Brace, S.; Peterson, D.L.; Horner, D. 1999. A guide to ozone injury in vascular plants of the Pacific 

Northwest. Gen. Tech. Rep. PNW-GTR-446. Portland, OR: U.S. Department of Agriculture, Forest 

Service, Pacific Northwest Research Station. 63 p. 

Brandenberg W., M. Farrington and S. Gottlieb. 2004. Razorback larval fish survey in the San Juan 

River during 1999-2002. Division of Fishes, Museum of Southwestern Biology, Department of 

Biology, University of New Mexico, Albuquerque, New Mexico. 

Brown, B. T. 1993. Winter foraging ecology of Bald Eagles in Arizona. Condor 95: 132–138. 

Buehler, D. A., T. J. Mersmann, J. D. Fraser, and J. K. D. Seegar. 1991. Nonbreeding Bald Eagle 

communal and solitary roosting behavior and habitat use on the northern Chesapeake Bay. J. 

Wildl. Manage. 55: 273–281. 

Buehler, D. A. 2000. Bald Eagle (Haliaeetus leucocephalus). In The Birds of North America, No. 506 

(A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA. 

BLM. Bureau of Land Management, Farmington Field Office. 2003. Farmington Proposed Resource 

Management Plan and Final Environmental Impact Statement BLN0NM-PL-03-014-1610. 

Burt, W. H. and R. P. Grossenheider. 1976. Peterson field guides: Mammals. 3rd Edition. Houghton 

Mifflin Company: New York. Pp. 289. 

Busnel,R.G. and John Fletcher (eds.). 1978. Effects of Noise on Wildlife. New York: Academic Press. 

Chester, D. N., D. F. Stauffer, T. J. Smith, D. R. Luukkonen, and J. D. Fraser. 1990. Habitat use by 

nonbreeding Bald Eagles in North Carolina. J. Wildl. Manage. 54: 223–234. 

Cornell University. 1993. Available online at www.naturesstandard.combioaccum.html 1993 

Crooks, K.R. 2002. Relative sensitivities of mammalian carnivores to habitat fragmentation. 

Conservation Biology 16:488-502. 
Biological Assessment of the Desert Rock Energy Project, April 2007 58

Crowder, M. R. and O.E. Rhodes. 2001. Avian collisions with power lines: A review. In Avian 

Interactions with Utility and Communication Structures. Workshop Proceedings . Charleston, 

S.C. EPRI Technical Report No. 1006907. R. Carlton, Project Manager. 

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Biological Assessment of the Desert Rock Energy Project, April 2007

Appendix A 

Regulatory Agency Correspondence 


















Biological Assessment of the Desert Rock Energy Project, April 2007

Appendix B 

Biological Evaluation 
Biological Evaluation of the Desert Rock Energy Project, April 2007 i

Biological Evaluation 

For the Proposed 

Desert Rock Energy Project 

PREPARED FOR: 

BUREAU OF INDIAN AFFAIRS

NAVAJO AREA OFFICE

GALLUP, NEW MEXICO

AND

NAVAJO NATION DEPARTMENT OF FISH AND WILDLIFE

WINDOW ROCK, ARIZONA

PREPARED BY: 

ECOSPHERE ENVIRONMENTAL SERVICES

4801 N. BUTLER SUITE 15101 

FARMINGTON, NEW MEXICO 87401 

APRIL 2007 
Biological Evaluation of the Desert Rock Energy Project, April 2007 ii

TABLE OF CONTENTS 

1.0 EXECUTIVE SUMMARY ....................................................................................................... 1 

2.0 DESCRIPTION OF THE PROPOSED ACTION..................................................................1 

2.1 Power Plant .............................................................................................................................2 

2.2 Access Roads ..........................................................................................................................3 

2.3 Transmission Lines .................................................................................................................5 

2.4 Water Well Fields ...................................................................................................................6 

2.5 BNCC Mine Lease ..................................................................................................................6 

3.0 DESCRIPTION OF THE ANALYSIS ....................................................................................7 

3.1 Affected Environment.............................................................................................................7 

4.0 SURVEY METHODS .............................................................................................................10 

4.1 Field Survey Preparation.......................................................................................................10 

4.2 Field Surveys.........................................................................................................................10 

5.0 SPECIAL STATUS SPECIES................................................................................................10 

6.0 EFFECTS OF THE PROPOSED ACTION .........................................................................15 

6.1 Ecological Risk Assessment..................................................................................................15 

6.2 Air Quality Effects ................................................................................................................15 

6.3 Water Quality Effects............................................................................................................16 

6.3.1 Surface Water Quality ...............................................................................................16 

6.3.2 Ground Water Quality...............................................................................................18 

6.3.3 Streamflow Effects......................................................................................................19 

6.4 Infrastructure Related Effects................................................................................................19 

6.5 Human Activity Effects.........................................................................................................21 

7.0 GENERAL MITIGATION MEASURES .............................................................................21 

8.0 SPECIAL STATUS SPECIES IMPACTS ............................................................................23 

8.1 San Juan milkweed (Asclepias sanjuanensis) .......................................................................23 

8.2 Cottam’s milkvetch (Astragalus cottamii) ............................................................................ 23 

8.3 Naturita milkvetch (Astragalus naturitensis).........................................................................24 

8.4 Mancos saltplant (Proatriplex pleiantha)...............................................................................24 

8.5 Parish’s alkali grass (Puccinellia parishii) ............................................................................25 

8.6 Banner-tail kangaroo rat (Dipodomys spectabilis)................................................................25 

8.7 Kit fox (Vulpes macrotis)......................................................................................................25 

8.7 Spotted bat (Euderma maculatum)........................................................................................26 

8.8 Brown pelican (Pelecanus occidentalis carolinensis)............................................................26 

8.9 Mountain plover (Charadrius montanus) ..............................................................................26 

8.10 Golden eagle (Aquila chrysaetos) .........................................................................................27 

8.11 Western burrowing owl (Athene cunicularia hypugea) ........................................................27 

8.12 Ferruginous hawk (Buteo regalis) .........................................................................................28 

8.13 American peregrine falcon (Falco peregrinus)......................................................................29 

8.14 Sora (Porzana carolina) .........................................................................................................29 

8.15 Roundtail Chub (Gila robusta) ..............................................................................................29 

8.16 Mottled sculpin (Cottus bairdi) .............................................................................................30 

8.17 Bluehead sucker (Catostomus discobolus)............................................................................30 

8.18 Northern leopard frog (Rana pipiens) ...................................................................................31 

8.19 Summary of Potential Impacts to Special Status Species .....................................................31 

9.0 BIOLOGICAL ASSESSMENT PREPARERS.....................................................................33 

10.0 CONSULTATION AND COORDINATION........................................................................33 

11.0 REFERENCES CITED...........................................................................................................34 
Biological Evaluation of the Desert Rock Energy Project, April 2007 ii

LIST OF FIGURES AND TABLES 

Table 2-1. Maximum Projected Ground Disturbance for Individual Project Components. 2 

Figure 1: Desert Rock Energy Project Proposed Action Including Sub-Alternatives. ......... 4 

Table 3-1. Maximum Projected Disturbance to Vegetation Communities Per Action 

Alternative. Desert Rock Energy Project 2007. ...........................Error! Bookmark not defined.

Table 5-1. Summary of Potential Impacts to Special Status Species Listed by the Navajo 

Nation Natural Heritage Program and the State of New Mexico With Potential to Occur in 

the Desert Rock Energy Project Analysis Area. ...................................................................... 11 

ATTACHMENTS 

ATTACHMENT A NAVAJO NATION NATURAL HERITAGE PROGRAM 

CONSULTATION LETTERS 

ATTACHMENT B GOLDEN EAGLE AND FERRUGINOUS HAWK NEST 

PROTECTION POLICY 
Biological Evaluation of the Desert Rock Energy Project, April 2007 1

BIOLOGICAL EVALUATION 

DESERT ROCK ENERGY PROJECT 

1.0 EXECUTIVE SUMMARY 

The purpose of this Biological Evaluation (BE) is to provide information about the potential 

environmental effects that development of the Desert Rock Energy, LLC proposed Desert Rock Energy 

Project would have on species listed as threatened, endangered or sensitive by the Navajo Nation 

Department of Fish and Wildlife (NNDFW) and the State of New Mexico. The proposed Desert Rock 

Energy Project would be located on Navajo Nation lands in San Juan County, New Mexico. The purpose 

of this survey was to adhere to the Endangered Species Act of 1973, as amended (16 U.S.C. 1531 et seq.), 

and the Navajo Nation code requirement for species of concern (17NNC507) administered by the Natural 

Heritage Program (NHP) of the NNDFW. State listed species are protected under the New Mexico 

Wildlife Conservation Act of 1978. (N.M. Stat. § 17-2-37) and the Endangered Plant Species Act (N.M. 

Stat. 1978 § 75-6-1). 

Potential impacts as a result of the proposed action to species listed by U.S. Fish and Wildlife Service 

(UFWS) as federally endangered, threatened, and/or candidate species, and proposed or designated 

critical habitat, are addressed in detail in the Biological Assessment (BA) (Ecosphere 2007). A draft 

environmental impact statement (DEIS) is being prepared in compliance with the National Environmental 

Policy Act (NEPA) to analyze and disclose probable effects of the proposed Desert Rock Energy Project. 

2.0 DESCRIPTION OF THE PROPOSED ACTION 

Desert Rock Energy, LLC is proposing to construct and operate a coal-fired power plant, that would 

produce up to 1,500 MW (megawatt) gross (1,366 MW net) of electricity. The proposed facilities include 

up to two 750-MW generation units, as well as a plant-cooling system, coal-handling facilities, power 

transmission interconnection facilities, a water-supply system, access to the plant site, waste-management 

operations and other ancillary facilities. The proposed action is summarized below in Table 2.1 in terms 

of the required facilities and the maximum ground disturbance per component. The proposed power plant 

is located approximately 30 miles southwest of Farmington in San Juan County, New Mexico and is 

entirely on the Navajo Nation (refer to Figure 1). More detailed information on the proposed action, 

including details on project construction, plant operation, maintenance and decommissioning is provided 

in the DEIS (URS 2007). 
Biological Evaluation of the Desert Rock Energy Project, April 2007 2

Table 2-1. Maximum Projected Ground Disturbance for Individual Project Components. 

Desert Rock Energy Project 2007. 

Project Component Alternative Maximum Anticipated Disturbance 

in Acres 

Power Plant Facility N/A 149 

Segment A 503 

Segment B 672 

Segment C 375 

Segment D 327 

Total if Sub-alternative A Selected 1,205 

Transmission Line 

Total if Sub-alternative B Selected 1,373 

Access Road N/A 21 

Sub-alternative A 942 Water Well Field 

Sub-alternative B 890 

BNCC Lease Area N/A 13,051 

2.1 Power Plant 

The power plant site would be located within a 592-acre area parcel immediately adjacent to and west of 

the existing BHP Navajo Coal Company (BNCC) lease area. Within the parcel, the footprint of the 

facilities would require approximately 149 acres. Ancillary facilities within the power plant site (i.e. 

administration building/control center, turbine hall, air-emission control equipment and facilities, 

maintenance shop, etc.) and operation of the plant are described in more detail in the DEIS (URS 2007). 

Up to 1.2 million tons of earth material is anticipated to be removed for the construction of the plant. The 

cut-and-fill activities, conducted using scrapers or excavators, would be balanced over the site such that 

soil would not need to be imported or exported. The plant site would be surrounded by fencing for 

security and safety purposes and normal access to the plant would be through a primary gate with security 

controls. 

The power plant, proposed as a mine mouth operation, would be fueled by sub-bituminous coal provided 

by the adjacent resources of the BNCC Lease Area. Operation of the power plant would require up to 

6.2 million tons of coal per year. The coal would be delivered from the BNCC Lease Area to the power 

plant via conveyor belt. 

State-of-the-art emission controls would be used to minimize emissions of potential air pollutants. Air 

pollution controls for the pulverized coal-fired boilers would consist of the following: 

• Low nitrogen oxide (NOx) burners and selective catalytic reduction to control NOx emissions; 

• Low sulfur coal and wet flue gas desulfurization to control sulfur dioxide (SO2) emissions; 

• Wet flue gas desulfurization and a wet stack to control acid gas emissions, including sulfuric 

acid mist; 

• Wet flue gas desulfurization to control mercury (Hg) emissions. Activated carbon and hydrated 

quicklime injection to be installed before the fabric filter baghouse if needed for additional 
Biological Evaluation of the Desert Rock Energy Project, April 2007 3

reductions, with secondary reductions in sulfur dioxide (SO2) emissions and sulfuric acid 

(H2SO4) mist; 

• A fabric filter to control particulate emissions; and 

• High efficiency combustion to control carbon monoxide (CO) and volatile organic compound 

emissions. 

Highly efficient supercritical boilers would operate at high temperatures (net heat rate of 8,792 Btu 

[British thermal unit] per kilowatt hour) and pressure to make steam to turn a steam turbine connected to 

a generator that would produce the electricity. Steam exhausted from the turbine would be cooled by a 

Heller natural-draft cooling system. This type of cooling system uses 80 percent less water than 

conventional mechanical-draft cooling systems. No cooling pond would be required. 

The power plant would have a 50-year design life without major capital improvements. At the end of its 

useful life, the power plant and all associated facilities would be decommissioned. All structures and 

equipment at the site would be dismantled and removed. All water wells would be decommissioned and 

abandoned in accordance with Navajo Nation procedures and regulations. Following removal and 

abandonment of facilities, any areas disturbed would be rehabilitated as near as possible to their original 

condition including all areas of the BNCC lease area disturbed by mining activities. All mining areas 

associated with Desert Rock will be reclaimed per the terms and conditions of BNCC’s Surface Mining 

Control and Reclamation Act (SMCRA) permit as administered by Office of Surface Mining (OSM). 

2.2 Access Roads 

Although existing access roads and two-tracks are available within the project area and along proposed 

utility and transmission corridor alignments, a new permanent access road to the proposed plant site is 

proposed. The proposed road alignment is approximately 2.24 miles in length requiring 21 acres of new 

ground disturbance. This access road would spur off of the existing Burnham Road that currently crosses, 

in a north-south direction, Areas V and IV of the BNCC lease. 
Biological Evaluation of the Desert Rock Energy Project, April 2007 4

Figure 1: Proposed Desert Rock Energy Project Preferred Alternative Including SubAlternatives. 
Biological Evaluation of the Desert Rock Energy Project, April 2007 5

2.3 Transmission Lines 

The proposed transmission lines would extend from the proposed plant site to the existing Arizona Public 

Service (APS) Four Corners Generating Station (Segments A or B and Segment C). After leaving the 

Four Corners Generating Station, the proposed transmission alignment would continue northward 

(Segment D) crossing the San Juan River and interconnecting with the proposed Navajo Transmission 

Project (NTP). There are two sub-alternative corridors being considered in the DEIS for the southernmost 

portion of the transmission alignment: Segments A and B (described below). With the exception of 

Segment D, which is proposed within a 250 feet-wide right-of-way (ROW), all other alternative 

transmission corridors would be within a 500-feet wide ROW. 

Segment A, the preferred alternative, would leave the plant site and would parallel the eastern side of the 

Chaco River, connecting with Segment C after 8.3 miles. The ROW for this sub-alternative would require 

503 acres. Sub-alternative Segment B would leave the plant site to the west, cross the Chaco River then 

parallel the western side of the Chaco River continuing northward and crossing the Chaco River again 

before connecting into Segment C after 11.1 miles. The ROW for this alternative would require 

approximately 672 acres. Segment C would be 6.2 miles in length requiring a 375 acre ROW, while 

Segment D is 10.8 miles in length and would require a 372 acre ROW. Segment D would cross the San 

Juan River and continue northward to tie into the currently proposed NTP. There are no sub-alternatives 

considered for transmission Segments C and D. 

Segments A or B would consist of 2 single-circuit 500kV transmission lines. Segment C would consist of 

1 single-circuit 500kV transmission line, which would parallel an existing 230kV line. Segment D would 

also consist of 1 single-circuit 500kV transmission line paralleling an existing 230kV line. All 

transmission line segments would be self-supporting, four-legged, steel-lattice tower structures 

approximately 135 feet in height with 1,200-1,600 feet of spacing between individual structures. 

At each tower site, leveled areas, or pads, approximately 30 feet by 40 feet would be needed to facilitate 

the safe operation of construction equipment, such as cranes. At each structure site, a work area of 

approximately 200 by 200 feet would be required for the location of structure footings, assembly of the 

tower, and equipment maneuvers. The work area would be cleared of vegetation only to the extent 

needed. After construction, disturbed areas not needed for normal maintenance of the transmission line 

would be graded to blend as near as possible with the natural contours, and revegetated with indigenous 

plant species. Areas would be reseeded prior to the season(s) when precipitation is normally received. 

Pilot lines would be pulled (strung) from structure to structure by helicopter and threaded through the 

stringing sheaves at each tower. Following the pilot lines, a larger diameter, stronger line would be 

attached to conductors to pull them through. Conductors and ground wires would be strung using 

powered pulling equipment at one end and powered tensioning equipment at the other end of a conductor 

segment. Sites for tensioning equipment and pulling equipment would be approximately 3 miles apart. 

The tensioning site would be an area approximately 200 by 200 feet. The pulling site would require 

approximately half the area of the tension site. 

During pre-design project development activities, a series of preexisting roads were field verified and 

mapped for access to proposed transmission tower sites resulting in selection of routes of which avoided 

disturbance of cultural and biologically sensitive areas. Existing roads will be used to the greatest extent 

possible; however some overland access on undisturbed areas would be required. It is expected that all 

biological and cultural resources of importance along or within all roads used for the project will be 

inventoried and monitored by a qualified biologist or archaeologist prior to construction related activities 

and that these resources will be avoided during long term maintenance activities of the project. 
Biological Evaluation of the Desert Rock Energy Project, April 2007 6

2.4 Water Well Fields 

The average annual water consumption demand of the Desert Rock Energy Project is estimated to be 

4,500 acre-feet per year (af/yr), or 2,795 gallons per minute (gpm), of continuous flow for a period of 40 

consecutive years. An additional 450 ac/ft per year would be available to meet Navajo municipal demand 

for a total of 4,950 ac/ft per year. The proposed and alternative water sources would be groundwater from 

the Morrison aquifer. Based on evaluations of the hydrogeologic characteristics of the Morrison aquifer, it 

was estimated that 10 to 20 new production wells could meet this anticipated water demand (URS 2005). 

Water from the Morrison aquifer was identified as suitable for industrial use through a study by URS in 

September 2005 and amended in September 2006. Data for the study came from previous studies, well 

data from Navajo Department of Water Resources, and water quality field tests. 

Two alternate water well field locations are being evaluated in the DEIS and in this BE. The preferred 

alternative Water Well Field B would include 13 wells located within the 592-acre power plant facility 

site, as well as an additional 7 wells spaced at 1-mile intervals along Segment A of the proposed 

transmission line corridor. The sub-alternative Water Well Field A would also be comprised of 20 water 

wells, all within an approximately 2 square mile area. Water Well Field A would also require the 

construction of a 12.4 mile utility corridor/water line. 

Each water production well and associated facilities would be enclosed within an 8-foot-high chain-link 

fence surrounding the well yard, requiring a 100 foot by 100 foot area (approximately 2 acres). Individual 

wells would be connected by collector pipelines to the main utility line, which would extend from the 

water well field to the proposed power plant site. Due to the topographic conditions, the pipelines would 

be pressurized only by the well pumps; no booster-pump station would be required. Overhead distribution 

power lines would be constructed to supply electricity to the wells and would be constructed in the same 

ROW paralleling the main water utility pipeline and collector pipelines. Access to the production wells 

would be needed for construction, operation, and maintenance. Access roads would be approximately 15-

feet wide and would be gravel roads constructed in accordance with Bureau of Indian Affairs (BIA) 

and/or Navajo Nation standards. The utility corridor for Water Well Field B would be approximately 12.4 

miles in length and constructed within a 100-foot wide ROW requiring a 149.7 acres. Following 

construction the utility corridor would have a permanent 10-foot wide ROW. 

2.5 BNCC Mine Lease 

The power plant would be constructed on a 592-acre parcel immediately adjacent to and west of the 

existing BNCC lease area. The coal fuel supply would be produced and conveyed by a conveyor belt 

from coal reserve Area IV South, and Area V of the BNCC lease area to proposed coal preparation 

facility located next to the power plant in Area IV North of the BNCC lease area. The production phase 

in Area IV South will last through approximately 2044. At that time, the mining operations within the 

BNCC Lease Area will transition to Area V of the mine lease. 

BNCC holds Surface Permit Number 2838 issued by the New Mexico Office of the State Engineer in 

October 1958. This permit provides BNCC a total diversionary right of 51,600 acre-feet annually, with a 

consumptive right of 39,000 acre-feet annually, for waters drawn from the San Juan River. The additional 

consumption associated with the expansion of the surface mining operations at the Navajo Mine required 

to supply coal to the Desert Rock Energy Project is estimated to be approximately 600 acre-feet annually. 

The additional consumption is within BNCC’s existing consumptive right and will cause no depletions to 

the San Juan River beyond those authorized under the current water right permit. 

A single public road, referred to as the Burnham Road Realignment, will be re-routed to suit the needs of 

mining operation on the BNCC lease area. This road requires re-alignment over its extent within Areas III 

and IV North of the lease to suit the needs of the current BNCC lease area operations, regardless of the 

disposition of the Desert Rock Energy Project. Navajo Mine staff have developed a preferred alignment 
Biological Evaluation of the Desert Rock Energy Project, April 2007 7

and have entered preliminary approval discussions with the BIA, the regulatory authority over the roads 

in the project area. 

3.0 DESCRIPTION OF THE ANALYSIS AREA 

This section describes components of the environmental setting of the area with potential to be impacted 

by the proposed action. Because a detailed description of the physical and biological characteristics of the 

analysis area is provided in the DEIS (URS 2007), this evaluation focuses on the physical and biological 

characteristics of the analysis area that have a direct relevance to special status plant and wildlife species 

protected by the NNDFW and the State of New Mexico. 

To account for factors that may affect special status species, such as emissions, noise and human and 

vehicle presence, the analysis area is defined by a 31-mile (50-km) radius from the proposed Desert Rock 

Energy Project power plant site. The 31-mile (50-km) buffer was chosen to be consistent with air quality 

analyses required for major source air quality permitting (U.S. Environmental Protection Agency 

[USEPA] 2005). 

3.1 Affected Environment 

The climate of the analysis area is classified as arid continental (BLM 2003). Because of its relatively 

high elevations, San Juan County, New Mexico experiences warm dry summers and cool dry winters 

(Western Regional Climate Center 2006). Average annual temperatures in and near the project area are in 

the low to mid 50’s, summer temperatures range from the mid 60’s to the low 90’s and winter 

temperatures range from the low 20’s to the low 40’s (Western Regional Climate Center 2006). The mean 

annual precipitation in Shiprock, New Mexico is 7.07 inches (Western Regional Climate Center 2006). 

Topographically, the proposed action is characterized by alternating series of rolling hills, broad alluvial 

terrain, and bottomed washes with eroded sandstone and clay mesas and ridges. The project site is located 

in relatively flat to gently rolling terrain that is interspersed with areas of extreme topographic relief, 

including steep ridges and buttes. Major topographic features in the analysis area include the Hogback 

Monocline and Shiprock Peak. Elevations in the analysis range from approximately 5,000 ft to 5,675 ft. 

The project area is surrounded by several high elevation areas, including the Chuska Mountains in 

northwest Arizona, Sleeping Ute in Colorado and New Mexico, and the San Juan Mountains in southwest 

Colorado and north-central New Mexico. 

The action area is geologically located within the Cretaceous and Quaternary deposits derived from 

Mancos Shale (Upper Cretaceous), Menefee formation, Cliff House Sandstone of the Mesaverde Group 

(Upper Cretaceous), Pictured Cliff Sandstone (Upper Cretaceous), Fruitland formation, (Upper 

Cretaceous), Lower Shale member, Eolian sand (Holocene and Pleistocene), Naha and Tsegi Alluvium, 

undifferentiated (Holocene), and Channel and flood-plain alluvium (Holocene) (Hunt 1978). 

There are about 10 named washes in the site area that will likely intersect or be proximal to infrastructure 

associated with the Desert Rock Energy Project. All of these washes are intermittent or ephemeral. Most 

of the washes discharge into the Chaco River, which is an intermittent water source in the analysis area. 

The Chaco River flows north into the San Juan River. Originating in the San Juan Mountains of 

southwest Colorado, the San Juan flows southward into New Mexico and then generally westward into 

Utah where it eventually becomes a tributary to the Colorado. The project area contains a single lake, 

Morgan Lake. Morgan Lake is a man-made lake situated adjacent to the Four Corners Generating 

Station, which utilizes water in the lake to cool its generating units. 

In addition to these large water bodies, the project area also contains scattered wetlands that are fed by 

springs and/or collection of surface water (i.e. stockponds). During the 2006 field season, Ecosphere 

Environmental Services (Ecosphere) conducted jurisdictional wetland delineations of all potential Waters 

of the U.S. within all project component ROWs and footprints. These surveys identified 2 areas that were 
Biological Evaluation of the Desert Rock Energy Project, April 2007 8

characterized as wetlands; one near the proposed power plant access road, southeast of the proposed 

power plant location and the other near the Water Well Field B (Ecosphere 2006). The southwestern 

corner of Morgan Lake is located within a 1-mile corridor of the southern end of the proposed Segment D 

transmission line alignment. Jurisdictional wetlands are also present along the margins of Morgan Lake 

(Ecosphere 2006). There are no jurisdictional wetlands within the proposed action area of disturbance. 

The primary source of groundwater in the San Juan Basin is derived from wells completed within 

surficial valley-fill deposits of Quaternary age and sandstones of Tertiary, Cretaceous, Jurassic, and 

Triassic age (Stone et. al 1983). Groundwater in the sandstone sequences generally is under confined 

conditions, resulting in an artesian flow from wells completed in these units. 

Vegetation in the Desert Rock Energy Project analysis area is dominated by Great Basin desert-scrub 

habitats (Dick-Peddie 1993). Great Basin desert-scrub is a cold desert ecosystem dominated by shrubs 

with a sparse understory of forbs and grasses; bare ground occurs in poor, alkaline soils (Fitzgerald et a. 

1994, Dick-Peddie 1993). Vegetative communities within the study area were identified using the 

Provisional Digital Land Cover Map for the southwestern United States (USGS National GAP Analysis 

Program 2004). There are 18 cover types occurring within the analysis area, including two non-vegetative 

cover classes, Open Water and Recently Mined or Quarried (Table 3.1). The Provisional Digital Land 

Cover Map for the southwestern United States identified areas that have been recently mined or quarried 

(USGS National GAP Analysis Program 2004). Portions of BNCC Permit Areas I, II and III have been 

reclaimed. To more accurately describe the study area, data from BNCC’s reclamation efforts were 

extrapolated to characterize reclaimed areas and then categorize into GAP Analysis classifications (BHP 

Billiton 2004). The maximum projected disturbance to vegetation communities per project component are 

provided in Table 3.1. 

Table 4-1. Maximum Projected Surface Disturbance in Acres to Vegetation Communities 

for the Proposed Action. Desert Rock Energy Project 2007. Habitat Type Power Plant Coal Processing Plant Transmission Line A Transmission Line B Transmission Line C and D Access Road 

Water Well Field A Water Well Field A Utility Corridor Water Well Field B BNCC Lease Areas 

Colorado Plateau 

Mixed Bedrock 

Canyon and 

Tableland 1.56 0.00 2.22 0.00 45.81 0.44 2.22 1.60 9.56 5.12 

Inter-Mountain 

Basins Shale 

Badland 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

Colorado Plateau 

Piñon-Juniper 

Woodland 0.00 0.00 1.11 0.00 15.35 1.11 0.00 0.00 10.67 6.00 

Inter-Mountain 

Basins Big 

Sagebrush Shrubland 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.11 

Colorado Plateau 

Mixed Low 

Sagebrush Shrubland 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

Colorado Plateau 

BlackbrushMormon-tea 

Shrubland 0.00 0.00 0.00 0.00 21.35 0.00 0.00 0.00 0.00 0.00 

Inter-Mountain 

Basins Mixed Salt 

Desert Scrub 24.69 10.01 307.13 338.33 235.29 4.45 47.59 61.50 447.68 1332.37 

Inter-Mountain 

Basins Semi-Desert 

Shrub Steppe 46.93 18.01 22.02 30.30 24.69 2.45 3.34 3.18 102.97 475.70 
Biological Evaluation of the Desert Rock Energy Project, April 2007 9

Inter-Mountain 

Basins Semi-Desert 

Grassland 75.84 70.94 166.80 274.31 298.01 11.34 0.00 31.07 302.90 5893.46 

Rocky Mountain 

Lower Montane 

Riparian 

Woodland/Shrubland 0.00 0.00 0.00 1.60 2.22 0.00 0.00 0.00 0.00 4.89 

Inter-Mountain 

Basins Greasewood 

Flat 0.00 1.78 3.34 24.30 23.80 0.44 

836.2

0 52.40 16.46 379.18 

Southern Colorado 

Plateau Sand 

Shrubland 0.00 0.00 0.00 0.00 4.67 0.00 0.00 0.00 0.00 0.00 

Open Water 0.00 0.00 0.00 0.00 3.34 0.00 0.00 0.00 0.00 3.78 

Barren Lands, Nonspecific 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

Agriculture 0.00 0.00 0.00 0.00 10.90 0.00 0.00 0.00 0.00 0.00 

Recently Mined or 

Quarried 0.00 0.00 0.00 0.00 14.90 0.00 0.00 0.00 0.00 0.00 

Invasive Southwest 

Riparian Woodland 

and Shrubland 0.00 0.00 0.00 0.00 4.67 0.00 0.00 0.00 0.00 0.00 

Invasive Annual and 

Biennial Forbland 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

Total 149 101 503 669 705 20 889 150 890 13,051 

Source: USGS National GAP Analysis Program 2006. Acreages are approximate based on polygon calculations. 

Semi-desert grasslands, salt desert scrublands, and semi-desert shrublands are similar in that they overlap 

somewhat in species composition, but vary by physical structure and vegetative density. For example, 

semi-desert grasslands are often dominated by alkalai saccaton (Sporobolus airoides), galleta (Hilaria 

jamesii) and Indian ricegrass (Stipa hymenoides), but also include scattered shrubs such as saltbush 

(Atriplex spp.), shadscale (Atriplex confertifolia), and greasewood (Sarcobatus vermiculatus). Salt desert 

scrublands are generally dominated by various species of saltbush or greasewood but also include many 

of the same understory grasses and herbaceous forbs as grassland communities. Semi-desert shrublands 

include vegetative communities dominated by shrub species such as rabbitbrush (Chrysothamnus spp.), 

sagebrush (Artemisia spp.), broom snakeweed (Gutierrezia sarothrae), or ephedra (Ephedra spp.) 

Riparian habitats within the analysis area include native, exotic, and mixed native-exotic riparian 

woodlands occurring along perennial and intermittent water sources. Native riparian woodlands are 

dominated by cottonwoods (Populus spp.) and willows (Salix spp.), whereas riparian exotics include 

saltcedar (Tamarix chinensis) and Russian olive (Elaeagnus angustifolia). These riparian communities are 

associated with the primary water sources in the project area, the Chaco River, the San Juan River and 

Morgan Lake. 

The analysis area supports a variety of natural vegetation communities and landscape features that offer a 

diversity of wildlife habitat types, including habitat for an assortment of mammals, birds, reptiles, 

amphibians, fish and invertebrates. While these habitat types correspond with the vegetation community 

types discussed above, they also are defined by a number of distinct landscape features such as washes 

and gullies, rock outcrops and hillsides, cliffs and taluses, and caves. All contribute to the diversity and 

abundance of wildlife in the area as they generally provide a microhabitat for wildlife uniquely adapted to 

or dependent on these features. 

Most wildlife species within the study area are adapted to drought conditions, including sparse vegetative 

cover and limited sources of permanent water. However, perennial sources of water in the study area 

support a relatively high concentration of vegetation and cover that contribute to increased wildlife 

diversity in these areas. While many species of wildlife commonly feed in upland habitats, they also 
Biological Evaluation of the Desert Rock Energy Project, April 2007 10

depend on riparian-wetland habitat for breeding and cover. The riparian-wetland habitats generally have 

more structured and complex vegetative assemblages, along with higher wildlife diversity than the 

surrounding upland areas. These areas effectively function as movement corridors for mammals and serve 

as congregation and feeding areas for a variety of bird species. 

4.0 SURVEY METHODS 

4.1 Field Survey Preparation 

Information used to compile this section was gathered from data collected during field-based evaluations 

conducted in 2004-2006, from reviews of published literature, and from the project Ecological Risk 

Assessment contained in the DEIS (URS 2007). Prior to conducting fieldwork, a list of Navajo Nation 

species of concern was obtained through consultation with the NHP. Species of concern include 

protected, candidate, and other rare or otherwise sensitive species. Consultation letters from the NHP are 

provided in Attachment A. New Mexico State listed species were retrieved from the New Mexico Natural 

Heritage Program (NMNHP) Biological and Conservation Data System (NMNHP 2006) and the New 

Mexico Rare Plant Technical Council (NMRPTC 2006). Federally listed species are addressed in the BA 

(Ecosphere 2007). A review of existing data sources was conducted prior to field work. A volume of 

baseline data has been prepared for the BNCC mine lease area and the proposed power plant site. 

4.2 Field Surveys 

Intensive biological investigations, including species-specific surveys for federally listed and special 

status flora and fauna were conducted during between the 2004 and 2006 field seasons by biologists and 

botanists from Ecosphere. In addition to surveys completed specific to the proposed action, biologists and 

botanists from Ecosphere have conducted numerous biological and botanical investigations within and 

adjacent to the boundaries of Navajo Mine, the Four Corners Generating Station, Shiprock and 

Nenanhazad Chapters, and along the eastern end of the Navajo Transmission Project, all areas within or 

immediately adjacent to the analysis area. As adequate baseline data exists for the fish species, speciesspecific surveys were not conducted for these aquatic species. Surveys were conducted according to U.S. 

Fish and Wildlife Service (USFWS) survey protocols or for those species for which no federal survey 

protocol has been established, by using other commonly accepted scientific survey methods. 

5.0 SPECIAL STATUS SPECIES 

Special status species habitat requirements and potential to occur in the proposed project area were 

evaluated based upon project-specific habitat analyses. Table 5.1 lists the special status species, their 

conservation status, habitat associations, and potential impacts resulting from the proposed project. 
Biological Evaluation of the Desert Rock Energy Project, April 2007 11

Table 5-1. Summary of Potential Impacts to Special Status Species Listed by the Navajo 

Nation Natural Heritage Program and the State of New Mexico With Potential to Occur in 

the Desert Rock Energy Project Analysis Area. 

Species Name New Mexico 

Status 

Navajo 

Nation 

Status 

Habitat Associations Potential Impacts 

Bolack’s sand verbena 

(Abronia bolackii)

Species of 

concern 

None 

Gypsiferous clay of the 

Ojo Alamo Formation, 

often on very steep 

hillsides at 5,250-5,750 

ft. 

No Impact 

This species was not found 

in the proposed construction 

area boundaries. Limited 

potential habitat occurs in 

the analysis area. 

San Juan false carrot 

(Aletes macdougalii ssp. 

breviradiatus)

Species of 

concern 

None 

Sandstone slabs and 

canyon walls, usually 

growing in crevices 

(rarely on deeper sandy 

soil) in piñon-juniper 

woodland at 5,800-

8,200 ft. 

No impact. 

There is no potential canyon 

woodland habitat for this 

species in the proposed 

construction area 

boundaries. 

Aztec gilia 

(Aliciella formosa) Endangered None 

Salt desert scrub 

communities in soils of 

the Nacimiento 

Formation between 

5,000-6,000 ft. 

No impact. 

This geologic formation 

does not occur in the 

proposed project 

construction boundaries. 

San Juan milkweed 

(Asclepias sanjuanensis)

Species of 

concern 

G4 

Sandy loam soils in 

juniper savanna and 

Great Basin desert 

scrub at 5,000-5,500 ft. 

May impact 

This species occurs within 

the proposed construction 

area boundaries. 

Chuska milkvetch 

(Astragalus chuskanus)

Species of 

concern 

None 

Degraded Chuska 

sandstone in openings 

in montane coniferous 

forest above 5,500 ft. 

No impact. 

No Chuska sandstone or 

coniferous forests occur in 

the project area. 

Cottam’s milkvetch 

(Astragalus cottamii)

Species of 

concern 

None 

Found in rimrock 

habitats often within 

weathered depressions 

and crevices in 

sandstone substrates of 

Cretaceous origin in 

piñon-juniper woodland 

at 5,000-6,000 ft. 

May impact. 

This species was not found 

in the proposed construction 

area boundaries. Limited 

suitable habitat occurs in the 

project area 

Chaco milkvetch 

(Astragalus 

micromerius)

Species of 

concern 

None 

Gypseous or limey 

sandstones in piñonjuniper woodland or 

Great Basin desert 

scrub at 6,600-7,300 ft. 

Usually associated with 

outcrops of sandstone 

that are blended with 

Todilto gypsum or 

limestone. 

No impact. 

Todilto gypsum or 

limestone is not found in the 

analysis area. The species 

was not found in the project 

area. 
Biological Evaluation of the Desert Rock Energy Project, April 2007 12

Species Name New Mexico 

Status 

Navajo 

Nation 

Status 

Habitat Associations Potential Impacts 

Naturita milkvetch 

(Astragalus naturitensis)

Species of 

concern 

G4 

Southwest Colorado 

and south of Coyote 

Canyon on rimrocks 

and slickrocks in piñonjuniper woodlands. 

May impact. 

This species was not found 

in the proposed construction 

area boundaries. Limited 

suitable habitat occurs in the 

project area 

Arboles milkvetch 

(Astragalus oocalycis)

Species of 

concern 

None 

Seleniferous clay soils 

with sagebrush, piñonjuniper woodland, and 

transitional areas 

between piñon-juniper 

woodland and 

ponderosa pine forest. 

No impact. 

No potential habitat occurs 

within the analysis area. 

This species has a relatively 

limited distribution centered 

on Navajo Reservoir. 

Zuni fleabane 

(Erigeron rhizomatus) Endangered G2 

Nearly barren detrital 

clay hillsides with soils 

derived from shales of 

the Chinle or Baca 

formations; usually on 

north or east-facing 

slopes in open piñonjuniper woodlands at 

7,300-8,000 ft. 

No impact 

There are no Chinle or Baca 

derived soils in the analysis 

area. Elevation within the 

analyis area ranges from 

5,000 to 5,675 ft. 

Navajo mountain phlox 

(Phlox cluteana)

Species of 

concern 

None 

Light to heavy shade on 

sandy soils in 

ponderosa pine forest 

between 6,000-10,000 

ft. 

No impact 

There are no ponderosa pine 

forests within the proposed 

construction area 

boundaries. 

Mancos saltplant 

(Proatriplex pleiantha)

Species of 

concern 

None 

Desert badlands of 

Colorado Plateau on 

saline clay soils of the 

Mancos and Fruitland 

shale formations 5,000-

5,500 ft. 

May impact. 

This species is known to 

occur within 2 miles of the 

project area. Potential 

habitat occurs within the 

project area. 

Parish’s alkali grass 

(Puccinellia parishii) Endangered G3 

Great Basin Desert and 

Chihuahuan Desert 

Scrub communities in 

alkaline springs, seeps, 

and cienegas. 

May Impact. 

This species was not found 

in the proposed construction 

area boundaries. Limited 

potential habitat occurs in 

the project area. 

Brack’s hardwall cactus 

(Sclerocactus cloveriae 

ssp. brackii)

Endangered None 

Sandy clay of the 

Nacimiento Formation 

in sparse shadscale 

scrub between 5,000-

6,000 ft. 

No impact. 

This geologic formation 

does not occur in the 

proposed project 

construction boundaries. 

Pronghorn 

(Antilocapra americana) None G3 

Grasslands or desertscrub with rolling or 

dissected hills or small 

mesas. 

No Impact 

Not known to occur in the 

project area. There were no 

signs of this species 

utilizing the project area.

Banner-tail kangaroo rat 

(Dipodomys spectabilis) None G4 

Great Basin desert 

grassland or desert 

scrub. Presence of 

grasses is necessary. 

May impact. 

This species occurs within 

the project area. 
Biological Evaluation of the Desert Rock Energy Project, April 2007 13

Species Name New Mexico 

Status 

Navajo 

Nation 

Status 

Habitat Associations Potential Impacts 

Kit fox 

(Vulpes macrotis) None G4 

Desert scrub or desert 

grassland with soft, 

alluvial or silty-clay 

soils, with sparse 

vegetation cover. 

May impact. 

This species occurs within 

the project area. 

Spotted bat 

(Euderma maculatum) Threatened None 

Found in ponderosa 

pine forests, piñonjuniper woodlands, and 

open semidesert 

shrublands. Rocky 

cliffs are necessary for 

roosting, as is access to 

water. 

May impact. 

This rare species was not 

observed in the project area. 

However, there is potential 

habitat for this species. 

Baird’s sparrow 

(Ammodramus bairdii) Threatened None 

Winters in southwest 

United States and 

northern Mexico. Local 

in native long grass 

prairies. 

No impact. 

May incidentally migrate 

through the analysis area. 

However, the area does not 

provide potential wintering 

habitat. 

Common blackhawk 

(Buteogallus anthracinus 

anthracinus) 

Threatened None 

In New Mexico an 

uncommon summer 

resident that is largely 

restricted to welldeveloped riparian 

habitats in the San 

Francisco, Gila, and 

Mimbres drainages. 

No impact. 

Rarely seen in San Juan 

County. This species 

unlikely to occur in the 

analysis area. 

Gray vireo 

(Vireo vicinior) Threatened None 

Closely associated with 

piñon/juniper 

woodlands with a 

variety of canopy 

covers. 

No impact. 

Piñon/juniper woodlands in 

the construction area 

boundaries are not extensive 

enough to offer potential 

habitat. 

Brown pelican 

(Pelecanus occidentalis 

carolinensis)

Threatened None 

Usually found in 

marine habitats in 

warmer waters in North 

America; except for the 

lower Colorado Basin 

and vicinity. It only 

rarely occurs inland. 

May impact. 

May incidentally migrate 

through the analysis area 

(Morgan Lake). However, 

the area does not provide 

potential nesting habitat. 

Mountain plover 

(Charadrius montanus) None G3 

Breeds in short sparse 

vegetation in disturbedprairies or semideserts 

with less than a twodegree slope. 

May impact. 

This species has been 

recorded as breeding within 

the BNCC mine lease area. 

Golden eagle 

(Aquila chrysaetos) None G3 

Open habitats in 

mountainous, canyon 

terrain. Nests primarily 

on steep cliffs and 

occasionally large trees. 

May Impact 

Known to nest in the 

analysis area. However, the 

proposed area of 

disturbance contains only 

potential foraging habitat. 
Biological Evaluation of the Desert Rock Energy Project, April 2007 14

Species Name New Mexico 

Status 

Navajo 

Nation 

Status 

Habitat Associations Potential Impacts 

Western burrowing owl 

(Athene cunicularia 

hypugea)

None G4 

Nests in ground 

burrows (often deserted 

prairie dog burrows) in 

dry open grasslands or 

desert scrub. 

May Impact 

This species occurs and 

nests within the proposed 

area of disturbance. 

Ferruginous hawk 

Buteo regalis) None G3 

Nests in badlands, flat 

or rolling grasslands 

and desert scrub. 

May Impact 

The proposed area of 

disturbance contains 

potential nesting and 

foraging habitat. 

American peregrine 

falcon 

(Falco peregrinus)

Threatened G3 

Cliffs that generally 

exceed 200 feet in 

height near permanent 

surface water 

May Impact 

Potential nesting habitat 

occurs along the San Juan 

River corridor. 

Sora 

(Porzana carolina) None G4 

Nests in wetlands with 

shallow to 

intermediate-depth 

water with fine leaved 

emergent vegetation. 

May impact. 

May incidentally migrate 

through the analysis area 

(Morgan Lake). However, 

the area does not provide 

potential nesting habitat. 

Roundtail Chub 

(Gila robusta) Endangered G2 

Pools, creeks, rivers; 

rare in water 

impoundments 

May Impact 

Known to occur from 

Shiprock to Lake Powell in 

the San Juan River. 

Mottled sculpin 

(Cottus bairdi) None G4 

Found in rubble and 

gravel riffles, less often 

in sand-gravel runs, of 

headwaters, creeks, and 

small rivers 

May Impact 

Known to occur in the San 

Juan River. 

Bluehead sucker 

(Catostomus discobolus) None G4 

Occupies a wide range 

of water condition 

within river/stream 

habitats. 

May Impact 

Known to occur in the San 

Juan River. 

Milk snake 

(Lampropeltis 

triangulum) 

None G4 

Found in high foothill 

grasslands and 

coniferous forest using 

rocks, logs, stumps and 

other objects as cover. 

No Impact 

Potential habitat for this 

species does not occur 

within the proposed 

disturbance area. 

Northern leopard frog 

(Rana pipiens) None G2 

Breeds in wetlands 

usually with permanent 

water and aquatic 

vegetation ranging from 

irrigation ditches to 

small streams, rivers, 

ponds and marshes. 

May Impact 

Potential habitat occurs 

along the San Juan River 

corridor and at Morgan 

Lake. 

Sources: Natural Heritage New Mexico and Navajo Nation Natural Heritage Program. 

NOTES: E = Endangered species; T = Threatened species; G2 = Group 2 species on the Navajo 

Endangered Species List (NESL); G3 = Group 3 species on the NESL; G4 = Group 4 species on the NESL 
Biological Evaluation of the Desert Rock Energy Project, April 2007 15

6.0 EFFECTS OF THE PROPOSED ACTION 

6.1 Ecological Risk Assessment 

Potential risks to ecological receptors from the proposed power plant chemical emissions were evaluated 

in combination with the concentrations of these chemicals already present in the environment, to the 

extent that existing conditions are known. The risk analysis generally followed risk assessment 

procedures developed by U.S. Environmental Protection Agency (USEPA). Details of the ecological risk 

evaluation are presented in the DEIS (URS 2007). The ecological assessment includes a screening process 

where chemicals of potential ecological concern (COPECs) are selected and the subsequent risk-based 

assessment where site-specific risks and impacts are evaluated. 

Results of the risk estimation process in terms of hazard quotients (HQs) on vegetation are provided in the 

Ecological Risk Assessment in the DEIS (URS 2007). Results of the ecological risk evaluation indicates 

that emissions of selenium or mercury or other metals from the proposed Desert Rock Power Plant are not 

expected to result in adverse affects to wildlife. 

6.2 Air Quality Effects 

Estimated emissions of chemical air toxics associated with the Desert Rock Energy Project were extracted 

from the air quality permit application prepared by ENSR for Desert Rock Energy, LLC and submitted to 

the USEPA Region 9. In addition, ENSR performed dispersion modeling to evaluate air quality impacts 

of the power plant on local and regional air quality, including the deposition of particulate matter (PM10), 

sulfates, nitrates, dioxin and six metals; arsenic, cadmium, chromium, lead, mercury, and selenium. 

Based on results of these studies, the primary air pollutants associated with the Desert Rock Energy 

Project are expected to be fugitive dust associated with construction and mining activities, as well as 

emissions of chemical air pollutants and toxics associated with operation of the power plant and exhaust 

emissions from vehicles and other equipment (URS 2007). Models predicting ozone concentrations were 

not evaluated because is not required under the Prevention of Significant Deterioration (PSD) permitting 

procedures and the modeled ambient concentrations of ozone precursor compounds (NOx and VOC) were 

deemed insignificant (per the PSD criteria). 

For the proposed alternatives, the total maximum controlled PM10 (particulate matter/fugitive dust) 

emissions from construction of the plant site, well fields, transmission lines and access road are estimated 

to be 147.7 tons/month. In the project area, the impact of dust pollution on vegetation and wildlife is 

expected to be of localized importance near construction areas. Likewise, because intensive construction 

is only expected to occur for less than 36 months, dust pollution that results from construction activities is 

expected to have only short-term impacts on vegetation and wildlife and would be limited to the time of 

construction disturbance. Impacts from fugitive dust resulting from mine operations would be low, 

localized and long term. 

During construction, gasoline and diesel fueled vehicles and equipment will generate gaseous and 

particulate exhaust emissions, including volatile organic compounds (VOCs), carbon monoxide (CO), 

nitrogen oxides (NOx) and PM10. In the DEIS, annual emissions for all diesel-fueled vehicles and 

equipment were calculated based on average engine horsepower for each type of vehicles and equipment, 

and an operating schedule of 10 hours/day, 6 days/week and 52 weeks/year. Annual emissions for 

gasoline-fueled pickup trucks and crew cabs were calculated based on a traveling distance of 10 miles/day 

during power plant construction, 25 miles/day during access road construction, and 50 miles/day during 

transmission line and water conveyance system construction, all with an operating schedule of 6 

days/week and 52 weeks/year (URS 2007). Maximum annual tailpipe emissions from plant employees 

commuting to the project site would be 13.5 tons VOC, 132.0 tons CO, 6.9 tons NOx, 2.7 tons PM10 and 

0.3 tons of SO2. These emissions would be mobile and distributed across a large rural area; therefore, the 

ambient air quality impacts would be considered negligible. Impacts from vehicle emissions resulting 

from mine operations would be low, localized and long term. 
Biological Evaluation of the Desert Rock Energy Project, April 2007 16

The DEIS (2007) for the Desert Rock Energy Project specifies that approximately 7,000 tons of coal will 

be combusted in the power plant facility each year. This will result in the emission of several chemical 

pollutants and toxicants including volatile organic compounds (VOCs), carbon monoxide (CO), nitrogen 

oxide (NOx) and PM10, as well as sulphur dioxide (SO2). Computer-based modeling analyses indicate that 

maximum predicted ambient concentrations of NOx (annual), SO2 (annual), and CO (1 hr and 8 hr) will be 

below the significant impact levels for these pollutants within 1 km of the proposed power plant site 

(URS 2007). In contrast, maximum annual predicted ambient concentrations of PM10 (24 hr and annual) 

and SO2 (3 hr and 24 hr) will be above significant impact limits for these pollutants within 1 km of the 

power plant facility. The model predicted air concentrations of the criteria pollutants decrease with 

greater distance from the proposed site. This analysis indicates that the predicted plant emissions are not 

expected to increase air concentrations of any of the criteria pollutants to concentrations exceeding the 

National Ambient Air Quality Standards (NAAQS) criteria, at any location from the power plant fence 

line out. 

The concentrations of chemical air pollutants that plants and wildlife in the project area will be exposed 

are expected to be variable and depend on location, wind direction, rainfall, and sunlight. Potential risks 

to ecological receptors (soil invertebrates, vegetation and wildlife) from the proposed plant’s chemical 

emissions were evaluated in combination with the concentrations of these chemicals already present in the 

environment, to the extent that existing conditions are known (URS 2007). Results of the ecological risk 

evaluation indicates that emissions of selenium or mercury or other metals from the proposed Desert 

Rock Power Plant are not expected to result in adverse affects to wildlife (URS 2007). 

6.3 Water Quality Effects 

6.3.1 Surface Water Quality 

Based on the results of air toxics modeling, it is estimated that the Desert Rock power plant could release 

up to 161 pounds of mercury per year through air emissions. The emitted mercury would consist of both 

particulates and vapors. The highest level of mercury emissions would occur within 0.36-km and 0.27-km 

from the stack (at an annual rate of 9.47E-03 mg/m2/yr) and most of that would be wet deposition. A 

small percentage of the total mercury coming out of the stack (0.2%) would be dry and the maximum 

deposition for this form of mercury (at an annual rate of 1.45E-07 mg/m2/yr) would occur about 5.3 km 

from the stack. For mercury, annual average deposition at Morgan Lake would be 1.36E-04 mg/m2/yr 

and the annual average deposition at the San Juan River where the proposed transmission line would 

cross the waterway would be 1.38E-04 mg/m2/yr. 

Mercury is an extremely mobile pollutant and is emitted from natural and anthropogenic sources, 

occurring in several different chemical states in the environment (USEPA 2005b). Mercury emissions 

may persist in vapor form in the atmosphere and travel large distances to be deposited, or may be 

deposited near the proposed plant site. Deposited mercury in water courses may be re-emitted to air, 

remain suspended or dissolve in the water, be deposited in sediments or absorbed or ingested by aquatic 

plants and wildlife (USFW 2005). A portion of mercury in water or sediment can be converted into 

methylmercury, which is easily absorbed by aquatic organisms and accumulates in aquatic vegetation, 

phytoplankton and invertebrates. 

The maximum reported total mercury concentration in the San Juan River of 1.6 μg/L (microgram/liter) is 

below the Federal MCL (maximum contaminant level) for mercury of 2 μg/L, and the maximum 

dissolved mercury concentration in the San Juan River of 0.3 μg/L is below the chronic AWQC (ambient 

water quality criterion) of 0.7 μg/L. The average existing dissolved mercury concentrations in the San 

Juan River at Shiprock Bridge during the period 1994-2001 was 0.1 μg/L. For the protection of aquatic 

wildlife, the federal chronic AWQC for dissolved mercury is 0.77 μg/L (USEPA 2006). It is estimated 
Biological Evaluation of the Desert Rock Energy Project, April 2007 17

that the Desert Rock power plant could release up to 114 pounds of mercury per year (which accounts for 

80% control of mercury) through air emissions. 

Mercury is an extremely mobile pollutant and is emitted from natural and anthropogenic sources, 

occurring in several different chemical states in the environment (USEPA 2005b). Mercury emissions 

may persist in vapor form in the atmosphere and travel large distances to be deposited, or may be 

deposited near the proposed plant site. Deposited mercury in water courses may be re-emitted to air, 

remain suspended or dissolve in the water, be deposited in sediments or absorbed or ingested by aquatic 

plants and wildlife (USFW 2005). A portion of mercury in water or sediment can be converted into 

methylmercury, which is easily absorbed by aquatic organisms and accumulates in aquatic vegetation, 

phytoplankton and invertebrates. The emitted mercury would consist of both particulates and vapors. The 

highest level of mercury emissions would occur within 0.36-km and 0.27-km from the stack (at an annual 

rate of 9.47E-03 mg/m2/yr) and most of that would be wet deposition. A small percentage of the total 

mercury coming out of the stack (0.2%) would be dry and the maximum deposition for this form of 

mercury (at an annual rate of 1.45E-07 mg/m2/yr) would occur about 5.3 km from the stack. 

For mercury, annual average deposition at Morgan Lake would be 1.36E-04 mg/m2/yr and the annual 

average deposition at the San Juan River where the proposed transmission line would cross the waterway 

would be 1.38E-04 mg/m2/yr. Currently, the maximum reported total mercury concentration in the San 

Juan River of 1.6 μg/L (microgram/liter) is below the Federal MCL (maximum contaminant level) for 

mercury of 2 μg/L, and the maximum dissolved mercury concentration in the San Juan River of 0.3 μg/L 

is below the chronic AWQC (ambient water quality criterion) of 0.7 μg/L. The average existing dissolved 

mercury concentrations in the San Juan River at Shiprock Bridge during the period 1994-2001 was 0.1 

μg/L. For the protection of aquatic wildlife, the federal chronic AWQC for dissolved mercury is 0.77 

μg/L (USEPA 2006). 

It is estimated that about 19 pounds of mercury would be deposited within 25 km of the plant. The San 

Juan River is about 28 km from the power plant site. The actual quantity of mercury deposition that 

could eventually enter the San Juan River system or Morgan Lake directly or via runoff is difficult to 

quantify. 

Selenium is an essential element for both aquatic and terrestrial wildlife. However, it also has the 

narrowest range of what is beneficial and what is detrimental. Selenium has been shown to mitigate the 

toxic effects of mercury and other heavy metals in some organisms. There is also evidence that it may 

reduce the uptake of mercury in some aquatic organisms while increasing the mercury uptake in different 

organisms. Aquatic wildlife is exposed to selenium through ingesting food containing selenium and not 

through direct exposure to the chemical in water. Selenium is a bioaccumulative pollutant, meaning it 

accumulates in the tissues of aquatic wildlife. However, unlike mercury, concentrations of selenium do 

not increase significantly (biomagnify) in animals at each level of the food chain going from prey to 

predator (USEPA 2004). 

The AWQC for total selenium is 5.0 μg/L, and the mean concentration of total selenium in the San Juan 

River during the period of 1994–2001 is only 0.73 μg/L – 15% of the criterion. According to the USFWS 

(2005), selenium concentrations in fish from Morgan Lake may pose health risks to people and wildlife 

that consume a large amount of fish from the lake. However, the average dissolved selenium 

concentration measured in Morgan Lake was 1.0 μg/L which is substantially lower than the USEPA 

(2006) chronic water quality criterion (5.0 μg/L [total]) and the Navajo Nation Aquatic Habitat Criterion 

(2.0 μg/L) (USFWS (2005). 

Based on the results of air toxics modeling, it is estimated that the Desert Rock power plant could release 

up to 9,133 pounds of selenium per year through air emissions. The maximum deposition point for 

selenium also would be within .36 and .27 km from the stack, at a rate of 3.38E+00 mg/m2/yr. The 
Biological Evaluation of the Desert Rock Energy Project, April 2007 18

annual average deposition at Morgan Lake would be 2.97E-02 mg/m2/yr and the annual average 

deposition at the San Juan River would be 3.01E-02 mg/m2/yr. The actual quantity of selenium 

deposition that could eventually enter the San Juan River system or Morgan Lake directly or via runoff is 

difficult to quantify. 

The proposed power plant would result in the deposition of mercury and selenium in the San Juan River 

and Morgan Lake and would incrementally add to existing concentrations. Heavy metal concentrations 

are likely to vary depending on location, prevailing winds and rainfall and a number of other factors. How 

this incremental increase in mercury and selenium would potentially affect different aquatic species, or 

those species which primarily feed on aquatic wildlife or vegetation, is difficult to quantify. Species 

would differ in the amount and pathway of heavy metals ingested, the rate of tissue bioaccumulation, and 

in what, if any, potential effects to growth, reproduction or longevity may occur. This would depend on 

many site specific and species specific factors. The ecological effects of mercury and selenium to aquatic 

wildlife remain greatly unknown and require additional study to fully understand (USFW 2005). Potential 

adverse impacts to area aquatic resources from incremental increases in mercury and selenium 

concentrations would be minor and long term. These impacts are not likely to result in a loss of species 

viability range-wide, nor cause a trend to federal listing. 

Sediment deposited into waterways can negatively impact aquatic plants in a number of ways. Sediment 

in water reduces light penetration, which can reduce the ability of plants to photosynthesize (USGS 

2006). Reduction in the ability of plants to photosynthesize can slow their growth and development. 

Sediment deposited in waterways can directly impact wildlife. For example, sedimentary particles can 

suffocate fish by clogging their gills and can also reduce respiratory efficiency of amphibians by adhering 

to their skin. Indirectly, sedimentation of waterways can reduce vegetation available as forage for wildlife 

when photosynthesis is impaired. 

Ground disturbance associated with construction and mining has the potential to increase sediments 

reaching the San Juan River. The power plant construction and BNCC mining operations must comply 

with Clean Water Act (CWA) regulations which require that surface-water runoff from constructed 

surfaces be controlled such as to “prevent, to the extent possible using the best technology currently 

available, additional contributions of suspended solids to streamflow, or runoff outside the permit area.” 

The CWA requires that discharges to streams meet all applicable water quality standards. Office of 

Surface Mining (OSM) approval procedures for controlling sediment transport include berms, terraces, 

sediment ponds, and other energy dissipative channel structures that allow water to pond and sediment to 

accumulate. Additionally, accidental fuel, lubrication or other hazardous material spills in the 

construction zone, depending upon the size, has potential to reach the San Juan River and adversely 

impact localized fisheries and/or downstream habitats such as nursery backwaters. 

Potential impacts to water quality from sedimentation or hazardous material spills would be mitigated by 

implementation of the construction Stormwater Management Plan and by the project Hazardous 

Materials Handling and Response Plan. Following implementation of these plans, potential impacts to 

water quality from increased sedimentation would be minor. 

6.3.2 Ground Water Quality 

Groundwater will be pumped from the Morrison aquifer to supply water for the Desert Rock Power Plant 

cooling processes. The average annual water consumption demand of the proposed Desert Rock Power 

Plant is estimated at 4,950 ac/ft per year, or 3,070 gallons per minute (gpm), of continuous flow for a 

period of 40 consecutive years. This is the volume used in well impact modeling simulations for the water 

well field location (URS 2007). 

 

A groundwater predictive computer model (Miller Brooks 2007), using the program MODFLOW, was 

constructed to evaluate the various combinations of well locations under Alternative B. The model 
Biological Evaluation of the Desert Rock Energy Project, April 2007 19

boundaries were constructed as a rectangle, from near Morgan Lake south to Burnham and from Shiprock 

east to Fruitland. The source aquifer was the Morrison Formation, assumed to be confined and at a 

constant thickness of 600 feet. Hydraulic conductivity for the Morrison Formation was estimated at 0.075 

to 0.175 ft/day. Simulations were run for 20 years and for 40 years. Drawdown contour lines of ten feet or 

greater were mapped onto the model surface. At the center of the northern portion of the proposed well 

field, drawdowns were 1,885 feet for the 20-year simulation and 2,010 feet for 40 years. The southern 

portion of the proposed well field incurred drawdowns of 1,920 feet for 20 years of pumping and 2,020 

feet for 40 years of pumping. If both well field locations are used, the maximum drawdown would be 

experienced at the southern center, and would total 960 feet for 20 years of pumping and 1,020 feet over 

40 years. 

After 40 years of pumping, a large cone of depression in the potentiometric surface of the Morrison 

Formation would be experienced at the project site. This cone would decrease radially from the center of 

the wellfield and approach zero feet of drawdown at about 10 miles. 

6.3.3 Streamflow Effects 

Given the distance, greater than 10 miles, between the water well field and San Juan River no effects to 

streamflows are expected from the extraction of 4,950 ac/ft per year from the Morrison Aquifer (URS 

2007). 

For mining operations, BNCC will utilize approximately 600 ac/ft per year of consumptive water rights 

from the San Juan River. BNCC use of existing San Juan River water rights and the effects on stream 

flow in the San Juan River have been previously analyzed and documented in the Final Environmental 

Impact Statement Navajo Reservoir Operations Navajo Unit - San Juan River New Mexico, Colorado, 

Utah (USDI Bureau of Reclamation 2006). Therefore, there would be no additional effects to stream 

flows in the San Juan River resulting from the proposed action. 

6.4 Infrastructure Related Effects 

Construction and operation of project components including the power plant facility, access roads, 

transmission lines and water well field will result in temporary ground disturbance, as well as the 

development of permanent structures that alter habitat for vegetation and wildlife in the analysis area. 

Table 2-1 in Section 2.0 above displays the disturbance per project component. 

Construction and operation of the power plant site is expected to disturb 149 acres of primarily grasslands 

(50%) and shrublands (49%). Construction and operation of the preferred transmission line alignment 

(Segments A, C and D) would disturb approximately 1,205 acres of primarily shrublands (49%) and 

grasslands (39%). Segment D contains portions of canyonlands (13%) and blackbrush-ephedragreasewood shrublands (13%). The sub-alternative transmission line (Segments B, C and D) would result 

in a total of approximately 1,373 acres of disturbance; 168 more acres than the preferred alternative that 

includes transmission line Segment A (503 acres). Construction and operation of the alternative 

transmission line Segment B would directly impact mostly inter-mountain basin mixed salt desert scrub 

lands and (50%) inter-mountain basin semi-desert grasslands (43%). 

Access road construction would permanently remove approximately 21 acres inter-mountain basin semidesert grasslands (57%) and inter-mountain basin mixed salt desert scrub lands and (22%). 

The water well field sub-alternative A would encompass about 890 acres, almost all of which is intermountain basin greasewood flats (93%). Vegetation would be removed from maximum of 45 acres 

within the water well field for construction, drilling and operation of 20 water wells, the construction of 

collector pipelines and an access road. This sub-alternative would necessitate construction of a 12.4 mile 

utility corridor/water pipeline which would directly impact 150 acres of vegetation. The dominant 

vegetation communities that occur along the utility corridor/water pipeline are inter-mountain basin 
Biological Evaluation of the Desert Rock Energy Project, April 2007 20

mixed salt desert scrub lands (42%), inter-mountain basin semi-desert grasslands (21%), and intermountain basin greasewood flats (34%). Total acreage for water well field sub-alternative B would be 890 

acres; the vegetation community in this area is co-dominated by inter-mountain basin semi-desert 

grasslands (33%) and inter-mountain basin mixed salt desert scrub (50%). Approximately 10.5 acres of 

piñon-juniper woodland occurs within the proposed water well field. 

Wildlife habitat within the BNCC Lease Areas IV and V would gradually be impacted on an ongoing 

basis as mining activities expand over time. A maximum of 13,051 acres would be removed and altered 

over the life of the lease areas, primarily grassland (68%), shrublands (27%), and blackbrush-ephedragreasewood shrublands (5%). 

Disturbance and removal of soil has potential to directly and indirectly impact vegetation in the project 

area. Temporary soil disturbance and permanent soil removal will likely kill live individuals, and may 

negatively impact seed sources. Likewise, creation of man-made structures including large buildings, 

roads, and mines may alter natural seed dispersal patterns, which could impact recruitment of plant 

species from living and dead stock. The density and diversity of vegetation species would be modified in 

areas reclaimed following construction. Disturbance of natural plant communities can lead to invasion of 

exotic species, which may be more likely to outcompete natives. 

Construction and operation of the power plant facility, access roads, transmission lines and water wells is 

likely to impact wildlife via two primary mechanisms: 1) through removal of habitat, and 2) by altering 

normal movement routes. Disturbance and removal of soil and vegetation will directly and indirectly 

impact wildlife by removing habitat that is used for foraging, burrowing/nesting, and breeding. In 

addition to direct physical removal of habitats, construction of power plant facilities, transmission lines, 

access roads and water well facilities is likely to impede normal wildlife movement patterns. Because of 

the size of the physical structures themselves, wildlife movement corridors may be disrupted. This may 

result in localized clumping and restricted dispersal among sub-populations. Over time, restricted 

movement and dispersal could reduce genetic diversity in the population as a whole, or could limit the 

ability of individual sub-populations to recolonize following random demographic or environmental 

events, for example disease epidemics or extreme drought. 

Noise is expected to be generated during construction of the proposed project components, including the 

power plant facilities, transmission line, access roads and water well field. The construction phase of the 

proposed project is projected to continue for at least 36 months. Conventional construction activities in 

the project area would result in a short-term increase in the ambient noise level resulting from the 

operation of construction equipment. The increase in noise levels would be primarily restricted to the 

areas surrounding construction zones and the magnitude of noise generated would depend on the type of 

construction activity, equipment used, duration of the activity, and distance between the noise source and 

the receiver. The DEIS provides detailed information on the maximum noise levels generated by typical 

construction equipment; however, the average sound level generated by construction equipment is 89 

dBA at 50 feet from the source (URS 2007). Because construction noise is expected to be below the 90 

dBA hourly levels recommended by the Federal Transit Administration, general impacts from noise are 

expected to be low. 

Once construction is completed, operation of the project components is expected to result in the ongoing 

generation of noise and vibrations throughout the project area for the lifetime of the project. According to 

the DEIS, operation of the power plant facility is expected to generate less than 30 dBAL at nearby sound 

receptors, which is below residential land use requirements. Vibrations resulting from operation of the 

power plant are also expected to have negligible impacts, as the equipment used in the power plant 

facility is designed to produce very low vibration levels and are designed to shut down automatically if an 

unforeseen imbalance develops. 
Biological Evaluation of the Desert Rock Energy Project, April 2007 21

6.5 Human Activity Effects 

Construction and operation of the Desert Rock Energy project will necessitate a substantial increase in 

human presence above existing levels. Human presence has the potential to disturb vegetation in the 

project area, particularly in areas where humans travel beyond the boundaries of established roads, 

walkways or structures. Vegetation could be directly impacted by humans trampling or damaging 

individual plants or plant communities and could be indirectly impacted by humans disrupting soils 

outside of established travel routes. Disruption and degradation of soil can lead to increased wind and 

water erosion, making it difficult for vegetation to become or remain established. Cryptogamic soil crusts, 

if encountered, are particularly vulnerable to human disturbance, as these crusts can be disrupted by very 

few passes with a vehicle or human footprint (Belnap and Gillette 1997). 

In general, wildlife tend to avoid contact or confrontation with humans. As such, wildlife in the Desert 

Rock analysis area may temporarily avoid areas where human disturbances are occurring, or may 

permanently emigrate from areas where human presence is more constant. This may result in alterations 

of nesting, foraging and breeding behavior in species that are particularly sensitive to human presence 

(Stillman et al. 2006). Wildlife may be especially sensitive to human presence during significant periods 

of their annual cycles, including the breeding season. Construction and operation of the proposed project 

will require extensive vehicle travel which may increase the likelihood of collisions with wildlife. 

Vehicle strikes have the potential to adversely impact a variety of wildlife species, including rabbits, 

coyotes, fox, birds, and deer. 

7.0 GENERAL MITIGATION MEASURES 

The following section discusses mitigation measures that would occur prior to, during, and after 

construction of the proposed action. Measures listed below are in addition to those described under 

individual special status species that may be impacted by the action alternative. General mitigation 

measures would serve to minimize or avoid impacts to special status species. Species specific mitigation 

measures are provided in the detailed analysis of impacts in Section 8.0. 

Prior to Construction 

• An Oil and Hazardous Materials Spill Prevention, Control, and Countermeasure Plan shall be 

prepared to address hazardous materials storage and spill prevention. 

• A Storm Water Pollution Prevention Plan shall be prepared and implemented for construction 

activities to control surface runoff, reduce erosion, and prevent sedimentation from entering 

waterbodies during construction. 

• An Environmental and/or Biological Resource Compliance Monitoring Plan shall be prepared for 

all construction projects to ensure implementation of mitigation measures described in pertinent 

resource sections of the DEIS (URS 2007). The plan shall identify the frequency and type of 

monitoring required by qualified natural/biological resources personnel. The plan shall be 

submitted for NNDFW approval prior to any construction.

• All construction personnel shall attend an environmental protection briefing prior to working on 

any construction site in the project area. This briefing is designed to familiarize workers with 

statutory and contractual environmental requirements and the recognition of and protection 

measures for sensitive vegetation community and wildlife habitats. 

• Protective barriers shall be placed around specified sensitive vegetation community and wildlife 

habitats as identified by the NNDFW. Barriers shall be installed prior to construction and field 

inspected by NNDFW personnel to verify proper placement. 

• Aboveground structures (i.e. transmission towers) shall be sited and designed in order to 

minimize disturbance to sensitive wildlife habitats and to minimize adverse effects to landscape 

features such as topography and vegetation. 
Biological Evaluation of the Desert Rock Energy Project, April 2007 22

• Imported soils, fills, or aggregates shall be free of deleterious materials (i.e. trash, construction 

debris, noxious weeds). Sources of imported materials shall be submitted for Navajo Nation 

approval prior to construction. 

• A Non-native Species Management Plan shall be prepared prior to the commencement of any 

ground-disturbing activities that specifies the locations and methods for removing non-native 

species, prescriptions for monitoring activities after construction, and reporting requirements. The 

plan shall be submitted for NNDFW approval prior to ground-disturbing activities. 

• A Revegetation Plan shall be prepared for approval by the NNDFW prior to the commencement 

of any ground-disturbing activities that prescribes plant salvage, revegetation, and postconstruction monitoring activities. 

• Preconstruction surveys shall be conducted, as specified by the NNDWF by a qualified biologist 

to identify the number, type, and location of special-status species potentially occur within the 

project area. 

• A construction work schedule shall be prepared for all construction projects that minimizes noise 

and human activity effects on wildlife in adjacent habitats. 

• If any grading, clearing, brushing, or construction occurs during the bird breeding season 

(approximately February 15 through August 31), a qualified biologist shall conduct a survey of 

the habitat to determine whether there are active bird nests in the area, including raptors and 

ground nesting birds. The survey would begin not more than three days prior the beginning of 

work. If an active nest is observed, a minimum 300-foot buffer (500 feet for raptors) would be 

established using temporary fencing. The buffer would be in effect as long as work is occurring 

and until the nest is no longer active. 

During Construction 

• All construction contractors shall implement and comply with requirements of the Oil and 

Hazardous Materials Spill Prevention, Control, and Countermeasure Plan prepared for all 

construction projects. 

• All construction contractors shall implement and comply with operational compliance 

requirements of the Storm Water Pollution Prevention Plan. 

• Construction activities shall be monitored by qualified natural resources personnel as outlined in 

the Environmental and/or Biological Resource Compliance Monitoring Plan. 

• All project construction contractors shall implement and comply with the Non-native Species 

Management Plan prepared for each project component. 

• All construction equipment entering the project area shall be cleaned by means of pressure 

washing and/or steam cleaning so as to arrive on site free of mud or seed-bearing material. 

• Vegetation salvage, seed collection, and revegetation shall be implemented as defined in the 

Revegetation Plan. Topsoil shall be salvaged, segregated during storage, and reused in the proper 

location and depth as specified by the NNDFW. 

• All construction activities will be completely confined to the areas of potential ground 

disturbance for each project component as described in in the Desert Rock Energy Project DEIS 

under the Preferred Alternative (URS 2006) Clearing of vegetation and ground disturbance shall 

be minimized to the greatest extent possible. 

• Stationary noise sources shall be located as far as possible from sensitive wildlife habitat areas. 

All on-site work that generates noise levels above 76 decibels at the site boundary shall be done 

between 7:00 a.m. and 7:00 p.m. 

• Excavation sites must be monitored or covered to avoid trapping wildlife, and routes of escape for 

wildlife should be maintained. The construction site shall be inspected daily for appropriate 

covering and flagging of excavation sites. Each morning the project area shall be inspected for 

wildlife trapped in excavation pits. A qualified biologist shall be available to inspect excavations 

before refilling occurs. 
Biological Evaluation of the Desert Rock Energy Project, April 2007 23

• Proposed electrical transmission and distribution lines will be designed and constructed utilizing 

"raptor-safe" design. The most complete manual on this work is: " Suggested Practices For 

Raptor Protection On Power Lines: The State of the Art in 1996" (APLIC 1996).

Post-Construction 

• All tools, equipment, barricades, signs, surplus materials, debris, and rubbish shall be removed 

from the project work limits upon project completion. 

• The success of revegetation efforts shall be monitored. Plant materials used for revegetation shall 

remain alive and in a healthy, vigorous condition for a period of one year after final acceptance of 

planting. The project site shall be monitored in accordance with the Nonnative Species 

Management Plan and Revegetation Plan. All plants determined to be in an unhealthy condition 

shall be replaced. 

8.0 SPECIAL STATUS SPECIES IMPACTS 

Detailed species evaluations of species that have the potential to be impacted by the proposed action 

alternatives are provided below. Specific mitigation measures for these species are also addressed. 

8.1 San Juan milkweed (Asclepias sanjuanensis) 

Populations of this species were located at three (3) dispersed areas in Area V of the BNCC mine lease 

area (Ecosphere 2005d). Four (4) widely dispersed locations were recorded within Area VI of the BNCC 

mine lease (Ecosphere 2004a, 2005e). Several scattered populations are located within the proposed 

power plant site (Ecosphere 2005a). No populations were found along the proposed transmission 

corridors, access road, water well fields or the utility corridor/water line (Ecosphere 2005c). This species 

may be more abundant than previously thought (pers. comm. Daniela Roth 2004). 

Impacts to this species would occur during soil removal and disturbance from mining activities and power 

plant construction that would result in plant mortality. Temporary and permanent soil disturbance may 

negatively impact seed sources. The seedbed in stored topsoils could potentially result in a loss of seed 

viability and decrease the success of recolonization during reclamation. Human presence has the potential 

to disturb vegetation in the project area, particularly in areas where humans travel beyond the boundaries 

of established roads, corridors, rights-of-way, or facilities. Vegetation could be directly impacted by 

humans trampling or damaging individual plants or plant communities and could be indirectly impacted 

by humans disrupting soils outside of established travel routes or construction areas. 

Impacts would be low to moderate and long term. Impacts are not likely to result in a loss of species 

viability range-wide, nor cause a trend to federal listing. 

Specific Mitigation Measures: Following the completion of preconstruction surveys, if it is determined 

that special status plant species occur within the project area, the NNDFW will be consulted in 

accordance with the project Environmental and/or Biological Resource Compliance Monitoring Plan to 

develop strategies to minimize or avoid impacts to identified species. 

8.2 Cottam’s milkvetch (Astragalus cottamii) 

The action area offers potential, but unoccupied habitat for this species. Potential habitat occurs within the 

piñon-juniper woodlands encompassing 2 acres on the proposed access road, 2 acres on transmission line 

Segment A, 13 acres on transmission line Segment C, 4 acres on transmission line Segment D, 11 acres in 

water well field sub-alternative B, and 24 acres within the BNCC mine lease area. This species was not 

observed within the proposed action area during surveys (Ecosphere 2004a, 2005a, 2005c, 2005d, 2005e). 

However, prolonged drought conditions in the area may have precluded germination over the past several 

years. 
Biological Evaluation of the Desert Rock Energy Project, April 2007 24

Human presence has the potential to disturb vegetation in the action area, particularly in areas where 

humans travel beyond the boundaries of established roads, corridors, rights-of-way, or facilities. Potential 

impacts would be from suitable habitat loss and modification. Dormant seedbeds may be adversely 

impacted by construction activities or long-term topsoil storage. Following the implementation of 

mitigation measures, impacts to potential, but currently unoccupied habitat would be low and long term. 

Specific Mitigation Measures: Following the completion of preconstruction surveys, if it is determined 

that special status plant species occur within the project area the NNDFW will be consulted in accordance 

with the project Environmental and/or Biological Resource Compliance Monitoring Plan to develop 

strategies to minimize or avoid impacts to identified species. 

8.3 Naturita milkvetch (Astragalus naturitensis) 

The action area offers potential, but unoccupied habitat for this species. Potential habitat occurs within the 

piñon-juniper woodlands encompassing; 2 acres on the proposed access road, 2 acres on transmission line 

Segment A, 13 acres on transmission line Segment C, 4 acres on transmission line Segment D, 11 acres in 

water well field sub-alternative B and 24 acres within the BNCC mine lease area. This species was not 

observed within the proposed action area during surveys (Ecosphere 2004a, 2005a, 2005c, 2005d, 2005e). 

However, prolonged drought conditions in the area may have precluded germination over the past several 

years. 

Human presence has the potential to disturb vegetation in the action area, particularly in areas where 

humans travel beyond the boundaries of established roads, corridors, rights-of-way, or facilities. Potential 

impacts would be from suitable habitat loss and modification. Dormant seedbeds may be adversely 

impacted by construction activities or long-term topsoil storage. Following the implementation of 

mitigation measures, impacts to potential, but currently unoccupied habitat would be low and long term. 

Specific Mitigation Measures: Following the completion of preconstruction surveys, if it is determined 

that special status plant species occur within the project area the NNDFW will be consulted in accordance 

with the project Environmental and/or Biological Resource Compliance Monitoring Plan to develop 

strategies to minimize or avoid impacts to identified species. 

8.4 Mancos saltplant (Proatriplex pleiantha) 

The action area offers potential, but unoccupied habitat for this species. Potential habitat occurs within the 

mine lease area and power plant site. This species was not observed within the proposed action area 

during surveys (Ecosphere 2004a, 2005a, 2005c, 2005d, 2005e). This species has been recorded within 

the BNCC mine lease area in the past (Marron et al. 1991) However, prolonged drought conditions in the 

area may have precluded germination over the past several years. The occurrence and abundance of 

Mancos saltplant is strongly influenced by climatic conditions. Seeds may remain viable in the soil for up 

to 10 years. In unfavorable years the species may be rarely observed, but can be locally abundant in 

favorable years (NMRPTC 1999). 

Human presence has the potential to disturb vegetation in the action area, particularly in areas where 

humans travel beyond the boundaries of established roads, corridors, rights-of-way, or facilities. Potential 

impacts would be from suitable habitat loss and modification. Dormant seedbeds may be adversely 

impacted by construction activities or long-term topsoil storage. Following the implementation of 

mitigation measures, impacts to potential, but currently unoccupied habitat would be low and long term. 

Specific Mitigation Measures: Following the completion of preconstruction surveys, if it is determined 

that special status plant species occur within the project area the NNDFW will be consulted in accordance 

with the project Environmental and/or Biological Resource Compliance Monitoring Plan to develop 

strategies to minimize or avoid impacts to identified species. 
Biological Evaluation of the Desert Rock Energy Project, April 2007 25

8.5 Parish’s alkali grass (Puccinellia parishii) 

The action area offers potential, but unoccupied habitat for this species. Potential habitat is limited to 

small patches of native riparian and mixed native-exotic adjacent to the transmission line Segment D 

crossing of the San Juan River, along the northern margin of Morgan Lake and along the Chaco River. 

This species was not observed within the proposed action area during surveys (Ecosphere 2004a, 2005a, 

2005c, 2005d, 2005e). However, prolonged drought conditions in the area may have precluded 

germination over the past several years. 

Human presence has the potential to disturb vegetation in the action area, particularly in areas where 

humans travel beyond the boundaries of established roads, corridors, rights-of-way, or facilities. Potential 

impacts would be from suitable habitat loss and modification. Dormant seedbeds may be adversely 

impacted by construction activities or long-term topsoil storage. Following the implementation of 

mitigation measures, impacts to potential, but currently unoccupied habitat would be low and long term. 

Specific Mitigation Measures: Following the completion of preconstruction surveys, if it is determined 

that special status plant species occur within the project area the NNDFW will be consulted in accordance 

with the project Environmental and/or Biological Resource Compliance Monitoring Plan to develop 

strategies to minimize or avoid impacts to identified species. 

8.6 Banner-tail kangaroo rat (Dipodomys spectabilis) 

This species has been documented (i.e. trapped) in the BNCC mine lease area and the power plant site 

(Ecosphere 2005b, Ecosphere unpublished data). Construction and operation of the power plant, access 

road, transmission lines and water well fields and mining activities would directly and indirectly bannertail kangaroo rat through habitat loss and modification. Increased human activity during construction and 

operation would result in avoidance of the area. Some individuals would be displaced to adjacent, 

undisturbed habitat with similar vegetation structure while some may permanently emigrate from the 

area. Species movement and dispersal in the area would be adversely impacted by the presence of human 

activity and increased noise. This may result in alterations of foraging and breeding behavior. This impact 

would be greater during significant periods of wildlife annual cycles, including the breeding season. 

Some incidental mortalities may occur during construction activities since this species less regularly uses 

burrows and is less mobile than larger mammals. Potential vehicle-wildlife collisions would also 

adversely impact this species. 

Impacts are not likely to result in a loss of species viability range-wide, nor cause a trend to federal 

listing. Impacts would be low and long term following the implementation of recommended mitigation 

measures. 

Specific Mitigation Measures: Prior to any ground disturbing activities, conduct reconnaissance surveys 

to document whether there are any banner-tail kangaroo rat mounds along or within 1⁄4-mile of proposed 

disturbance areas. Should active burrows be detected, consult with the NNDFW to determine impact 

minimization or avoidance measures. 

8.7 Kit fox (Vulpes macrotis) 

The action area provides potential habitat for this species. The species has been recorded as occurring in 

the mine lease area and power plant site (Ecosphere 2005b, Ecosphere unpublished data). Construction 

and operation of the power plant, access road, transmission lines and water well fields and mining 

activities would directly and indirectly kit fox through habitat loss and modification. Increased human 

activity during construction and operation would result in avoidance of the area. Some individuals would 

be displaced to adjacent, undisturbed habitat with similar vegetation structure while some may 

permanently emigrate from the area. Movement and dispersal in the area would be adversely impacted by 

the presence of human activity and increased noise. This may result in alterations of foraging and 

breeding behavior. This impact would be greater during significant periods of wildlife annual cycles, 
Biological Evaluation of the Desert Rock Energy Project, April 2007 26

including the breeding season. Some incidental mortalities may occur during construction activities since 

this species less regularly uses burrows and is less mobile than larger mammals. Potential vehicle-wildlife 

collisions would also impact this species. Habitat loss and fragmentation may result in a decreased prey 

base for this species. Additionally, young and nursing adult females may be harmed during construction 

activities if natal burrows are destroyed. 

Impacts are not likely to result in a loss of species viability range-wide, nor cause a trend to federal 

listing. Recommended mitigation measures would minimize impacts to kit fox. Potential impacts would 

be low and long term. 

Specific Mitigation Measures: Prior to any ground disturbing activities, conduct reconnaissance 

surveys to document whether there are any kit fox burrows along or within 1⁄4-mile of proposed disturbance 

areas. Should active burrows be detected, consult with the NNDFW to determine impact minimization or 

avoidance measures. 

8.7 Spotted bat (Euderma maculatum) 

Potential habitat for this species occurs along the San Juan River corridor where Transmission Line D 

crosses the San Juan River and within areas of the BNCC mine lease area and power plant site. The 

species has not been recorded in action area (Ecosphere 2005b, Ecosphere unpublished data). 

Potential impacts would be from suitable habitat loss and modification. Bats foraging or migrating 

through the area would likely avoid the area due to increased human activity during construction and 

operation. Impacts would be low and long term following the implementation of general mitigation 

measures. 

8.8 Brown pelican (Pelecanus occidentalis carolinensis) 

There is one record of this species occurring during migration at Morgan Lake (BISONM 2006). This 

species would likely occur as an incidental migrant along the San Juan River corridor within the 

transmission line Segment D alignment or at Morgan Lake. Potential nesting habitat does not occur 

within the transmission line Segment D alignment. Impacts to this species would be limited to temporary 

avoidance of the river corridor and Morgan Lake during construction of transmission line D. These 

impacts would be negligible and short term 

8.9 Mountain plover (Charadrius montanus) 

This species has been recorded as breeding with the BNCC lease area (Ecosphere unpublished data). 

Construction and operation of the power plant, access road, transmission lines and water well fields and 

mining activities would directly and indirectly this species through habitat loss and modification. 

Increased human activity during construction and operation would result in avoidance of the area. Some 

individuals would be displaced to adjacent, undisturbed habitat with similar vegetation structure while 

some may permanently emigrate from the area. Movement and dispersal in the area would be adversely 

impacted by the presence of human activity and increased noise. This may result in alterations of foraging 

and breeding behavior. Disturbance or construction during breeding season could result in unsuccessful 

mating, nest abandonment, or an unsuccessful reproductive effort. 

Impacts are not likely to result in a loss of species viability range-wide, nor cause a trend to federal 

listing. Implementing mitigation measures would minimize potential impacts which are expected to be 

low and long term. 

Specific Mitigation Measures: A pre-construction survey to determine presence/absence and no ground 

disturbance activities within occupied habitat during the period between April 1 and July 15 would 

minimize impacts to mountain plover. 
Biological Evaluation of the Desert Rock Energy Project, April 2007 27

8.10 Golden eagle (Aquila chrysaetos) 

There is no potential nesting habitat for this species within the action area; however, the power plant site, 

mine lease area, access road, transmission line alignments and water well fields do provide potential 

foraging habitat for this raptor. This species is known to nest within 1-3 miles of the action area 

(Ecosphere unpublished data, Hawks Aloft 2005). Construction and operation of the power plant, access 

road, transmission lines and water well fields and mining activities would directly and indirectly impact 

golden eagle through habitat loss and modification. Habitat loss and fragmentation may indirectly result 

in a decreased prey base for this species. Increased human activity during construction and operation 

would result in avoidance of the area. Some individuals would be displaced to adjacent, undisturbed 

habitat with similar vegetation structure while some may permanently emigrate from the area. Species 

movement and dispersal in the area would be adversely impacted by the presence of human activity and 

increased noise. This may result in alterations of foraging and breeding behavior. In addition, electrical 

transmission and distribution lines may negatively impact golden eagles by causing direct mortality and 

disrupting breeding, nesting, and foraging behaviors. 

Impacts are not likely to result in a loss of species viability range-wide, nor cause a trend to federal 

listing. Following the implementation of mitigation measures outlined below, potential impacts would be 

low and long term. 

Specific Mitigation Measures: If possible, construction will be timed to avoid activities within specified 

buffers (TBD by the NNDWF), of known raptor breeding areas until after young have fledged. If 

construction must occur within the specified protection zone for a given nest, NNDFW will prescribe 

additional mitigation (e.g., screening the nest from construction activity, monitoring the nest during 

construction) to protect the nest from disturbance, to be determined on a case-by-case basis. 

Mitigation measures approved by the NNDFW should be employed to avoid disturbing any current or 

future potential area golden eagle nesting sites. The following are recommended 

conservation/coordination measures that will, at a minimum, be implemented: 

3⁄4 Avoid conducting construction or other disruptive human activities between January 15th and 

May 30th to avoid sensitive nesting time periods for golden eagle; 

3⁄4 If these time periods cannot be avoided, conduct a pre-activity raptor survey to determine the 

presence/absence of courting and/or nesting raptors within a 1 mile radius of proposed 

activities; 

3⁄4 If occupied raptor territories or nests are identified, develop a Monitoring Plan in coordination 

with the NNDFW to monitor raptor behavior during any NNDFW approved activities. This 

Monitoring Plan would include procedures for terminating/delaying activities if raptors are 

being impacted by the activities. 

8.11 Western burrowing owl (Athene cunicularia hypugea) 

This species has been recorded as breeding within the BNCC mine lease area and along the transmission 

line Segment B alignment (Ecosphere 2004a, Ecosphere unpublished data). Construction and operation of 

the power plant, access road, transmission lines and water well fields and mining activities would directly 

and indirectly western burrowing owl through habitat loss and modification. Increased human activity 

during construction and operation would result in wildlife avoidance of the area. Some individuals would 

be displaced to adjacent, undisturbed habitat with similar vegetation structure while some may 

permanently emigrate from the area. Species movement and dispersal in the area would be adversely 

impacted by the presence of human activity and increased noise. This may result in alterations of foraging 

and breeding behavior. Disturbance or construction during breeding season could result in unsuccessful 

mating, nest abandonment, or an unsuccessful reproductive effort. 
Biological Evaluation of the Desert Rock Energy Project, April 2007 28

Though individuals would be impacted by the proposed action alternatives, the population as a whole 

would not. Mitigation measures for burrowing owl are provided below. Potential impacts would be low 

and long term following the implementation of mitigation measures. 

Specific Mitigation Measures: To avoid direct impact to any burrowing owl or nest, conduct a preconstruction survey no more than 30 days prior to construction according to the Burrowing Owl Survey 

Protocol and Mitigation Guidelines (California Burrowing Owl Consortium 1993). If owls are found to be 

using the site and avoidance is not feasible, a passive relocation effort (displacing the owls from the site) 

may be conducted, subject to the approval of the NNDFW. 

If construction activities occur during the owl breeding season, and if burrowing owls are observed on or 

within 250 feet of a project site during preconstruction surveys, a 250-foot protective buffer will be 

established with the placement of a barrier fence. The fence will remain in place for the duration of the 

breeding season. The fence integrity will be monitored by a qualified biologist. 

8.12 Ferruginous hawk (Buteo regalis) 

There is potential nesting habitat for this species within BNCC mine lease area and there is potential 

foraging habitat within the proposed plant site, transmission corridors, access roads and water well fields. 

The species is known to nest within 1-3 miles of the action area (Ecosphere unpublished data, Hawks 

Aloft 2005). Construction and operation of the power plant, access road, transmission lines and water 

well fields and mining activities would directly and indirectly ferruginous hawk through habitat loss and 

modification. Increased human activity during construction and operation would result in avoidance of 

the area. Some individuals would be displaced to adjacent, undisturbed habitat with similar vegetation 

structure while some may permanently emigrate from the area. Species movement and dispersal in the 

area would be adversely impacted by the presence of human activity and increased noise. This may result 

in alterations of foraging and breeding behavior. In addition, electrical transmission and distribution lines 

may negatively impact ferruginous hawks by causing direct mortality and disrupting breeding, nesting, 

and foraging behaviors. Habitat loss and fragmentation may result in a decreased prey base for this 

species. 

Impacts are not likely to result in a loss of species viability range-wide, nor cause a trend to federal 

listing. Following the implementation of mitigation measures outlined below, potential impacts would be 

low and long term. 

Specific Mitigation Measures: The proposed action would adhere to the NNDFW newly developed and 

implemented Ferruginous Hawk Nest Protection Policy provided in Attachment B. 

If possible, construction will be timed to avoid activities within specified buffers (TBD by the NNDWF), 

of known raptor breeding areas until after young have fledged. If construction must occur within the 

specified protection zone for a given nest, NNDFW will prescribe additional mitigation (e.g., screening 

the nest from construction activity, monitoring the nest during construction) to protect the nest from 

disturbance, to be determined on a case-by-case basis. 

Mitigation measures approved by the NNDFW should be employed to avoid disturbing any current or 

future potential area ferruginous hawk nesting sites. The following are recommended 

conservation/coordination measures that will, at a minimum be implemented: 

3⁄4 Avoid conducting construction or other disruptive human activities between January 15th and 

May 30th to avoid sensitive nesting time periods for ferruginous hawk; 

3⁄4 If these time periods cannot be avoided, conduct a pre-activity raptor survey to determine the 

presence/absence of courting and/or nesting raptors within a 1 mile radius of proposed 

activities; 
Biological Evaluation of the Desert Rock Energy Project, April 2007 29

3⁄4 If occupied raptor territories or nests are identified, develop a Monitoring Plan in coordination 

with the NNDFW to monitor raptor behavior during any NNDFW approved activities. This 

Monitoring Plan would include procedures for terminating/delaying activities if raptors are 

being impacted by the activities. 

8.13 American peregrine falcon (Falco peregrinus) 

There is no potential nesting habitat for this species within the action area; however, the site does provide 

potential foraging habitat for this raptor species. Outside the action area, the San Juan River corridor 

offers potential nesting habitat. Species movement and dispersal in the area would be adversely impacted 

by the presence of human activity and increased noise. This may result in alterations of foraging behavior. 

Electrical transmission and distribution lines may negatively impact this species by causing direct 

mortality and disrupting breeding, nesting, and foraging behaviors. 

Mitigation measures outlined below would minimize or avoid impacts to this species. Potential impacts 

would be low and long term following the implementation of mitigation measures. 

Specific Mitigation Measures: A pre-construction survey to determine presence/absence and no ground 

disturbance activities within occupied habitat during the period between April 1 and July 15 would 

minimize impacts. 

8.14 Sora (Porzana carolina) 

This species has been recorded as a transient at Morgan Lake. This species would likely occur within the 

San Juan River corridor within the transmission line Segment D alignment or at Morgan Lake. Potential 

nesting habitat does not occur within the transmission line alignment, which is located approximately 1⁄2 

mile from the Morgan Lake, nor is there potential nesting habitat where the proposed transmission line 

crosses the San Juan river. Impacts to this species would be limited to temporary avoidance of the river 

corridor and Morgan Lake during construction. These impacts would be negligible and short term 

8.15 Roundtail Chub (Gila robusta) 

Currently, roundtail chub is occasionally found in the San Juan River near the mouths of the Mancos and 

Animas rivers (Carman 2006). The power plant would result in the deposition of small quantities of 

mercury and selenium in the San Juan River. Pollutant concentrations are likely to vary depending on 

location, prevailing winds and rainfall and other factors. A more detailed discussion is provided in 

Section 6.3.1 under Surface Water Quality Effects. The additive effect of mercury and selenium 

deposition to existing concentrations in the San Juan River will result in minor impacts to surface water 

quality. However, these impacts are not expected to exceed AWQC standards for the protection aquatic 

wildlife. Potential adverse impacts to area aquatic resources from incremental increases in mercury and 

selenium concentrations would be minor and long term. These impacts are not likely to result in a loss of 

species viability range-wide, nor cause a trend to federal listing. 

Impacts to this aquatic species would be potential impacts occurring during transmission line construction 

activities that result in discharge of sediment into the San Juan River. Human activity during construction 

in portions of the San Juan River that these species are known to frequent has the potential to directly 

impact these species by causing temporary dispersal. Additionally, accidental fuel, lubrication or other 

hazardous material spills in the construction zone, depending upon the size, has potential to reach the San 

Juan River and adversely impact localized fisheries and/or downstream habitats such as nursery 

backwaters. 

Following implementation of mitigation measures, potential impacts would be minor and long term. 
Biological Evaluation of the Desert Rock Energy Project, April 2007 30

Specific Mitigation Measures: Potential impacts from sedimentation or hazardous material spills would 

be mitigated by implementation of the construction Stormwater Management Plan and by the project 

Hazardous Materials Handling and Response Plan. 

8.16 Mottled sculpin (Cottus bairdi) 

On the Navajo Nation, this species is known only from the New Mexico reach of the San Juan River. The 

power plant would result in the deposition of small quantities of mercury and selenium in the San Juan 

River. Pollutant concentrations are likely to vary depending on location, prevailing winds and rainfall and 

other factors. A more detailed discussion is provided in Section 6.3.1 under Surface Water Quality 

Effects. The additive effect of mercury and selenium deposition to existing concentrations in the San Juan 

River will result in minor impacts to surface water quality. However, these impacts are not expected to 

exceed AWQC standards for the protection aquatic wildlife. Potential adverse impacts to area aquatic 

resources from incremental increases in mercury and selenium concentrations would be minor and long 

term. These impacts are not likely to result in a loss of species viability range-wide, nor cause a trend to 

federal listing. 

Impacts to this aquatic species would be potential impacts occurring during transmission line construction 

activities that result in discharge of sediment into the San Juan River. Human activity during construction 

in portions of the San Juan River that these species are known to frequent has the potential to directly 

impact these species by causing temporary dispersal. Additionally, accidental fuel, lubrication or other 

hazardous material spills in the construction zone, depending upon the size, has potential to reach the San 

Juan River and adversely impact localized fisheries and/or downstream habitats such as nursery 

backwaters. 

Following implementation of mitigation measures, potential impacts would be minor and long term. 

Specific Mitigation Measures: Potential impacts from sedimentation or hazardous material spills would 

be mitigated by implementation of the construction Stormwater Management Plan and by the project 

Hazardous Materials Handling and Response Plan. 

8.17 Bluehead sucker (Catostomus discobolus) 

Known throughout the San Juan River and its tributaries. The power plant would result in the deposition 

of small quantities of mercury and selenium in the San Juan River. Pollutant concentrations are likely to 

vary depending on location, prevailing winds and rainfall and other factors. A more detailed discussion is 

provided in Section 6.3.1 under Surface Water Quality Effects. The additive effect of mercury and 

selenium deposition to existing concentrations in the San Juan River will result in minor impacts to 

surface water quality. However, these impacts are not expected to exceed AWQC standards for the 

protection aquatic wildlife. Potential adverse impacts to area aquatic resources from incremental increases 

in mercury and selenium concentrations would be minor and long term. These impacts are not likely to 

result in a loss of species viability range-wide, nor cause a trend to federal listing. 

Human activity during construction in portions of the San Juan River that these species are known to 

frequent has the potential to directly impact these species by causing temporary dispersal. Additionally, 

accidental fuel, lubrication or other hazardous material spills in the construction zone, depending upon the 

size, has potential to reach the San Juan River and adversely impact localized fisheries and/or downstream 

habitats such as nursery backwaters. 

Following implementation of mitigation measures, potential impacts would be minor and long term. 

Specific Mitigation Measures: Potential impacts from sedimentation or hazardous material spills would 

be mitigated by implementation of the construction Stormwater Management Plan and by the project 

Hazardous Materials Handling and Response Plan. 
Biological Evaluation of the Desert Rock Energy Project, April 2007 31

8.18 Northern leopard frog (Rana pipiens) 

This species has not been recorded in the action area. Potential habitat for this species is limited to 

riparian areas adjacent to the San Juan River and at Morgan Lake. Removal of approximately 1.8 acres 

shrub riparian and upland habitat within the floodplain of the San Juan River would result in a minimal 

short term disturbance to potential habitat. Impacts to this species would be short term occurring during 

transmission line construction activities that result in discharge of sediment into the San Juan River. 

Additionally, accidental fuel, lubrication or other hazardous material spills in the construction zone, 

depending upon the size, has potential to reach the San Juan River and adversely affect potential habitat. 

Following implementation of mitigation measures, potential impacts would be negligible. 

Specific Mitigation Measures: Potential impacts from sedimentation or hazardous material spills would 

be mitigated by implementation of the construction Stormwater Management Plan and by the project 

Hazardous Materials Handling and Response Plan. 

8.19 Summary of Potential Impacts to Special Status Species 

The proposed project would result in the permanent removal of approximately 450 acres of vegetation 

and wildlife habitat for construction of the power plant, access road and water well field. Since specific 

designs have not been completed, construction of the transmission lines would remove or modify an 

undetermined acreage within the proposed ROWs; 1,205 acres for sub-alternative A and 1,373 acres for 

sub-alternative B. The actual disturbance within the ROWs would result from temporary overland access, 

tower sites, and staging sites and would be much less than the permitted acreage. The BNCC mine lease 

would modify the largest amount of acreage by contemporaneous mining of 13,051 acres over the 

expected 50 year life of the project. The impact to habitats in the mine lease area would be moderate to 

major as some aspects of these habitats will be irretrievably lost (such as natural rock outcrops) while 

these habitats will be reclaimed in accordance with SMRCA standards of reestablishing pre-mining 

species compositions and community densities and production. 

Impacts to special status species would be minimized by the implementation of general mitigation 

measures and species specific mitigation measures such as pre-construction presence/absence surveys 

prior to breeding season. Potential impacts are not likely to result in a loss of species viability range-wide, 

nor cause a trend to federal listing. 

Approximately seven isolated populations of San Juan milkweed would likely be destroyed by 

construction of the proposed project. The seedbed would likely be adversely affected through soil 

removal and or stock piling. The proposed project would result in the removal of generally small isolated 

areas of potential, but unoccupied habitat for Cottam’s milkvetch, Naturita milkvetch, Mancos saltplant, 

and Parish’s alkali grass. 

Impacts to brown pelican and sora would generally be limited to temporary dispersal during construction 

activities. There would be no loss of potential nesting habitat for these waterfowl. 

Potential, but unoccupied habitat for spotted bat would be modified or removed by the proposed action. 

Occupied habitat for kit fox and banner-tail kangaroo rat would be modified or removed by the proposed 

project resulting in displacement to adjacent suitable habitat. These two species may also experience 

some mortality due to construction activities and/or vehicular collisions. 

Mountain plover and western burrowing owl have been previously recorded as breeding within the 

analysis area with the largest expanses of occupied and potential but unoccupied habitat occurring within 

the BNCC mine lease area and the water well field sub-alternative A. Due to the removal or modification 
Biological Evaluation of the Desert Rock Energy Project, April 2007 32

of potential nesting habitat, these species would likely be displaced to suitable adjacent habitat. Impacts to 

golden eagle would be limited to removal or modification of foraging habitat and temporary avoidance of 

areas where increased human and vehicular activities occur. The removal of ferruginous hawk potential, 

but unoccupied nesting habitat within the BNCC lease area would result in long term impacts. There 

would also be a decrease in available foraging habitat for this species and a likely change in movement 

and dispersal. The addition of transmission lines would increase the likelihood of potential golden eagle, 

ferruginous hawk and American peregrine falcon collisions/electrocutions. 

Wildlife exposed to mercury via their diet may be subject to reproductive failure, immune system 

impairment, behavioral aberrations, motor dysfunctions, or even direct toxicity. Most at risk are those 

animals at upper trophic levels that feed on fish, or on other animals that feed on fish. While little reliable 

information is available, there are no known instances of mercury intoxication of wildlife in New Mexico. 

Assessment of the impact of mercury on wildlife is difficult however, since some of the symptoms 

associated with chronic mercury poisoning may not be immediately apparent, resulting in reduced 

functionality, inappropriate breeding behavior, or early mortality by some other mechanism, e.g. impaired 

predator evasion. Minor increases in mercury and selenium, and other potentially toxic elements, 

reaching the San Juan River from air pollution deposition may contribute to adversely impacting aquatic 

species’ reproductive success. In addition, mercury that is sorbed to sediment is still available to 

methylating bacteria when carried into the anoxic zones of river beds and reservoirs where methylation 

occurs. These impacts would be minor and long term and are not likely to result in a loss of species 

viability range-wide, nor cause a trend to federal listing. 
Biological Evaluation of the Desert Rock Energy Project, April 2007 33

9.0 BIOLOGICAL ASSESSMENT PREPARERS 

Joey Herring B.S. Environmental Biology 

Jennifer Zahratka M.S. Zoology 

John Dodge B.S. Environmental Biology 

10.0 CONSULTATION AND COORDINATION 

Sonja Detsoi, Rita Whitehorse-Larson 

Natural Heritage Program 

Navajo Fish and Wildlife Department 

P.O. Box 1480 

Window Rock, AZ 86515 

Daniela Roth 

Natural Heritage Program 

Navajo Fish and Wildlife Department 

P.O. Box 1480 

Window Rock, AZ 86515 

David Mikesic 

Natural Heritage Program 

Navajo Fish and Wildlife Department 

P.O. Box 1480 

Window Rock, AZ 86515 
Biological Evaluation of the Desert Rock Energy Project, April 2007 34

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ATTACHMENT A 

NAVAJO NATION NATURAL HERITAGE PROGRAM 

CONSULTATION LETTERS 


















Biological Evaluation of the Desert Rock Energy Project, April 2007 ii

ATTACHMENT B 

GOLDEN EAGLE AND FERRUGINOUS HAWK 

NEST PROTECTION POLICY 




Biological Evaluation of the Desert Rock Energy Project, April 2007 iii

Appendix C 

Ecological Risk Assessment (excerpt) 
[This appendix was excerpted from the Risk Analysis that is included in this Draft EIS, in 

its entirety, as Appendix J. The excerpt is not reproduced here.]