Prepared for: Prepared by:

City of Palmdale/Inland Energy AECOM

60138827

July 2011

Addendum to the Palmdale Hybrid 

Power Project Biological Assessment
 Prepared for: Prepared by: 

 City of Palmdale/Inland Energy AECOM 

 60138227 

 July 2011 

Addendum to the Palmdale Hybrid 

Power Project Biological Assessment 

_________________________________ 

Prepared By Craig Wentworth 

_________________________________ 

Reviewed By Sara J. Head 
AECOM

July 2011 Addendum to the PHPP Biological Assessment, Los Angeles County, California Page 1

Introduction

This document serves as an Addendum to the Biological Assessment (BA) for the Palmdale Hybrid 

Power Project (PHPP or Project), Los Angeles County, California, March 2009. The BA for the PHPP 

was submitted to the U. S. Environmental Protection Agency (EPA) on March 31, 2009 along with the 

application for a Prevention of Significant Deterioration (PSD) permit (AECOM 2009a) for the PHPP, 

including a request that the EPA initiate consultation for the Project with the U.S. Fish and Wildlife 

Service (USFWS) under Section 7 of the Endangered Species Act. As noted in the cover letter for the 

PSD Application and BA in March 2009, the City of Palmdale (the Applicant) anticipated that EPA 

would seek concurrence with the USFWS that the PHPP “may affect but is not likely to adversely 

affect” federally listed species.

Subsequent to the submittal of the PSD application and BA to the EPA in March 2009, the 

licensing/permitting of the Project has progressed under the California Energy Commission’s (CEC’s) 

siting process. This Addendum to the BA is needed to address two additional potential components of

the Project identified during this CEC process: 1) an alternative transmission line route that was 

developed and assessed by the CEC; and 2) a list of ten specific road segments in and around the 

City of Palmdale that may be paved to create emission reduction credits for the PHPP. The proposed 

alternative transmission line and road paving were both added to the Project scope subsequent to the 

completion of the BA. This BA Addendum contains the description of these additional Project 

components. This BA Addendum provides analyses in support of a determination of may affect but is 

not likely to adversely affect for the federally listed desert tortoise (Gopherus agassizii) and a 

determination of no effect for the federally listed arroyo toad (Anaxyrus californicus).

Project Description, Alternative Transmission Line Route 4

In the CEC’s Final Staff Assessment (FSA), December 2010, the CEC Staff identified a number of 

alternative transmission line routes in response to comments received on the Staff’s Preliminary Staff 

Assessment. Of these alternatives, Staff determined that the Alternative Transmission Line Route 4, 

the Partial Underground/Overhead Transmission Route (Alternative Route 4), is a feasible alternative. 

In the Presiding Member’s Proposed Decision (PMPD), issued in June 2011 (CEC 2011b), the CEC 

has proposed approving both the Applicant’s proposed transmission line route and Staff’s Alternative 

Route 4. Both options are expected to be fully approved by the Energy Commission in August 2011 

and if so, the Applicant will have approval to construct the transmission line along either route. 

Alternative Route 4 would run along the proposed gas pipeline and proposed reclaimed water pipeline

for part of the route, and would be considerably shorter than the Applicant’s proposed route. The 

partial underground transmission line route would follow the PHPP underground fuel gas supply 

pipeline route for 6.75 miles and then would proceed approximately 6 miles as an overhead route, for 

a total route length of approximately 12.8 miles. The Alternative Route 4 is shown in Figure 1.

Alternative Route 4 would be shorter than the Applicant’s proposed transmission line and would 

consolidate impacts of the transmission, water, and gas pipelines along one roadway for about half of 

its length (CEC 2010). However, Alternative Route 4 would impact a wider corridor since the gas 

pipeline and the transmission line would be separated to meet regulatory requirements. Although 

longer, the Applicant’s proposed route would follow existing roads and/or an existing SCE 

transmission line, and would have minimal impacts to habitat along the route. Although temporary 

during construction, Alternative Route 4 would cause greater disruption to businesses along this busy 

traffic route and would increase traffic congestion. Maintenance of an underground line over the life of 

a project is also much more difficult to do than an overhead line, and access would be a problem. 

Importantly, both routes were found to have insignificant impacts to biological resources with the 

implementation of the CEC’s required mitigation measures (CEC 2010; CEC 2011b). Thus, neither 

Alternative Route 4 nor the proposed project route would result in a significant impact to biological 

resources.
AECOM

July 2011 Addendum to the PHPP Biological Assessment, Los Angeles County, California Page 2

Project Description, Roads Proposed for Paving

In addition, the Applicant has proposed to pave segments of up to ten roads in the vicinity of the 

PHPP to offset PM10 emissions from the Project. The Applicant identified 11 road segments as 

having the highest potential for reducing PM10 emissions in a May 2009 submittal in response to CEC 

Staff data requests (AECOM 2009b), and later agreed to drop one of these segments (number 7) from 

further consideration due to concerns raised in public comments on the Project. The ten road 

segments under consideration for road paving are listed in Table 1. The locations of these road 

segments within the City of Palmdale or surrounding Los Angeles County are shown in Figures 2.a 

and 2.b.

Addendum to the Palmdale Hybrid Power Project Biological Assessment –

Table 1. Potential Road Segments for Generation of PM10 ERC

Segment Street From To

1 Avenue B 90th Street West 30th Street West

2 Avenue S-2 96th th Street East 106th Street East

3 110th Street East Avenue L Columbia Way/Avenue M

4 40th Street West Avenue N Avenue N-8

5 Avenue Q 90th Street East 110th Street East

6 Avenue S-6 96th Street East 106th Street East

7 Barrel Springs Road Sierra Highway 25th Street East

8 Avenue T-10 87th Street East 96th Street East

9 Avenue N-8 Bolz Ranch Road 30th Street West

10 Avenue G 90th Street East 120th Street East

11 Carson Mesa Road El Sastre Vincent View Road

Source: PHPP Responses to CEC Data Request Set 2 (91-162), May 1, 2009

As described in the CEC Staff’s Rebuttal Testimony (CEC 2011a), proposed road segments 2, 4, 6, 8, 

9, and 11 are located within urban areas characterized by large lot residential communities supporting 

single family homes, landscaping, and open ruderal fields where homes have either not been 

developed or have been removed (Table 2). Road segments 1 and 5, while in more rural areas,

support scattered residences, fallow agricultural lands, and natural desert scrub communities. Active 

farming occurs along portions of road segment 5. Road segment 11, while largely supporting natural 

lands, is located adjacent to the railroad and parallels Highway 14.

Road segments 3, 7, and 10 are located in more isolated areas supporting various native and nonnative plant communities. For example, road segment 3 appears to be a lightly travelled road that 

appears to be within the active portion of an ephemeral drainage. This area is bordered by large tracts 

of natural lands to the east and scattered rural residences to the west. Road segment 7 (Barrel 

Springs Road) also passes through native habitat in close proximity to Una Lake. Several small 

drainages also appear to bisect this road. Due to concerns raised about road segment 7, the 

Applicant agreed to drop this segment from further consideration.
AECOM

July 2011 Addendum to the PHPP Biological Assessment, Los Angeles County, California Page 3

Addendum to the Palmdale Hybrid Power Project Biological Assessment –

Table 2: Road Location and Existing Conditions

Road 

Segment

Segment 

Name

Existing Conditions

Potential 

for 

Sensitive 

Species

Expected 

ROW Width 

(feet)

1 Avenue B Low density rural residences, fallow and 

active agricultural lands, desert scrub, and 

ephemeral drainages

Moderate 40

2 Avenue S-2 Residential development on approximately 

one-acre lots. Landscape vegetation, 

ruderal fields, and disturbed areas

Low 40

3 110th Street 

East

Primarily natural lands, road appears to be 

within active channel of seasonal drainage.

Moderate 92

4 40th Street 

West

Urban residential lands. Landscaped 

areas.

Low 40

5 Avenue Q Low density rural residences, desert scrub, 

and various ephemeral drainages

Moderate 92

6 Avenue S-6 Residential development on approximately 

one-acre lots. Landscape vegetation, 

ruderals fields, and disturbed areas

Low 40

7 Barrel 

Springs Road

Primarily natural lands with sparse rural 

residences. Supports various scrub 

communities, juniper woodland, and 

several drainages. Close to Una Lake,

known to support nesting vireos.

Moderate 92

8 Avenue T-10 Residential development on approximately 

one-acre lots. Landscape vegetation, 

ruderals fields, and disturbed areas

Low 40

9 Avenue N-8 Urban residential lands. Landscaped 

areas.

Low 60

10 Avenue G Primarily fallow agricultural lands likely 

supporting rabbit bush scrub, various 

desert scrub, and several ephemeral 

drainages.

Moderate 40

11 Carson Mesa 

Road

Primarily natural lands with various scrub 

communities, juniper woodland, and small 

ephemeral drainages. General parallels a 

railroad ROW and State Highway 14

Moderate 40

Source: CEC Staff Rebuttal Testimony, 2011a.

ROW = Right of Way
AECOM

July 2011 Addendum to the PHPP Biological Assessment, Los Angeles County, California Page 4

Listed and Proposed Species in the Project Area

Desert Tortoise

The Mojave population of the desert tortoise, which includes all tortoises occurring west and north of 

the Colorado River, is listed as threatened by the U.S. Fish and Wildlife Service (USFWS) and the 

California Department of Fish and Game (CDFG). The desert tortoise is most common in desert 

scrub, desert wash, and Joshua tree habitats in a variety of terrain types, including alluvial fans, 

valleys, rocky hillsides, and washes. The species requires friable soil for burrow and nest construction. 

Burrows are typically found at the base of shrubs, in the interspaces between shrubs, and 

occasionally in caliche soil bank areas or underneath boulders/rocks. Desert tortoises are herbivores 

that feed on a variety of plants, including annual herbs and perennial grasses. The Project area 

contains no designated critical habitat for the desert tortoise.

Arroyo Toad

The arroyo toad is a medium-sized toad, and adults range from 2.2 to 2.6 inches in length (USFWS 

1999). Adults typically require overflow pools adjacent to the inflow channel of streams that are 

generally third order or greater and generally free of predators. Normally, shallow pools with sandy or 

gravely bottoms surrounded by little woody vegetation are preferred. Regular disturbance in the form 

of flooding is required to maintain areas of sparsely vegetated, sandy stream channels and terraces, 

which are used by adults and sub-adults for foraging and burrowing (USFWS 2001). Outside the 

breeding season, arroyo toads use a wide range of habitats in both upland (to a distance of at least 

3,740 feet from the upland-riparian ecotone) and riparian areas (Holland and Sisk 2001). Upland 

habitats used by arroyo toads include coastal sage scrub, chaparral, oak woodland, grassland, 

riparian, and agricultural habitats (Griffin and Case 2001; USFWS 2001). The Project area contains 

no designated critical habitat for the arroyo toad.

Assessment of Potential Impacts, Alternative Route 4 

Transmission Line 

Desert Tortoise

Desert tortoise potentially occurs along the northern portion of the underground segment of Alternative 

Route 4, west and south of the PHPP site. This area is considered to have a low potential to support 

the species due to the highly disturbed, degraded, and fragmented condition of the surrounding land. 

In addition, these parcels are confined by development and are further fragmented by Sierra Highway 

and U.S. Air Force Plant 42. Therefore, direct and indirect effects to the species would have a 

very low potential to occur with implementation of Alternative Route 4.

No desert tortoise designated critical habitat is present on or near the Project site. The nearest 

designated critical habitat and known occupied habitat for this species is located approximately 16 

miles northeast within the Fremont-Kramer Desert Wildlife Management Area (DWMA) (AMEC 2008). 

Vegetation communities identified on the Project site (e.g., desert scrub, desert wash, and Joshua 

tree) are known to be used by desert tortoises, but focused surveys conducted in 2006 on the power 

plant site did not detect desert tortoise or sign and focused surveys conducted in 2008 did not detect 

desert tortoise on the Project site, buffer zone, or zone of influence (ZOI) transects. One burrow that 

potentially could be used by a tortoise (Class 5: good condition, undetermined species) was found 

during 2008 surveys on the 3,960-foot ZOI transect west of the power plant site. The mouth of the 

burrow was overgrown with vegetation, and no sign of recent use was evident. Focused surveys 

conducted in 2008 did not detect desert tortoise or sign on adjacent U.S. Air Force Plant 42. The 

highly fragmented nature of the Project site with numerous barriers (e.g., highways, railroad tracks, 
AECOM

July 2011 Addendum to the PHPP Biological Assessment, Los Angeles County, California Page 5

development) makes it highly unlikely that desert tortoises are present or could wander there from 

adjacent lands – the connectivity to known occupied habitat is very low. Known occupied habitat is 16 

miles northeast of the Project site, spanning numerous barriers. 

Desert tortoise also have not been detected along the Applicant proposed transmission line alignment, 

and tortoises are not expected to occur within the Alternative Route 4 alignment due to the urban 

setting and disturbed habitat that occurs there.

Potential direct and indirect impacts to wildlife at the PHPP plant site and along the linear facilities will 

be reduced to less-than-significant levels with impact avoidance and minimization measures. To 

reduce potential effects to the desert tortoise, Conditions of Certification will be contained in the CEC 

Final PHPP Decision (anticipated to be approved in August 2011) that apply to protection of desert 

tortoise and other biological resources in and near the PHPP. The Conditions of Certification include 

preconstruction surveys, installation of tortoise exclusion fencing, clearance surveys, monitoring; and 

verification that all desert tortoise impact avoidance, minimization, and compensation measures have 

been implemented. Additional measures will require the development and implementation of a Raven 

Monitoring, Management, and Control Plan and the payment of a raven management fee to minimize 

impacts to desert tortoise resulting from increases in raven populations. These Conditions of 

Certification will apply to either transmission line route alternative, depending on which one is selected 

by the Applicant for construction. Implementation of these conditions will further reduce or avoid 

the already low potential for impacts to the desert tortoise. Based on the low potential for 

occurrence or impacts, no compensatory mitigation for the loss of desert tortoise habitat is 

proposed.

Arroyo Toad

Designated critical habitat for the federally listed arroyo toad is not present along Alternative Route 4. 

The nearest critical habitat designated for the arroyo toad (Unit 21 Little Rock Creek Basin) occurs 2.6 

miles south of the Segment 2 transmission line. Construction of the Alternative Route 4 would not 

affect critical habitat for this species.

Arroyo toads were not detected in 2009 during protocol surveys at the Applicant proposed 

transmission line route crossing of Little Rock Creek. It was previously concluded that the arroyo toad 

was not observed during 2006 or 2008 surveys because of a lack of suitable habitat (i.e., lack of 

flowing water; City of Palmdale 2008). In addition, the Biological Assessment (AECOM 2009a) 

indicated that the most recent sighting of this species was in 2001, three miles upstream of the Project 

crossing. Protocol surveys for arroyo toad were conducted at the proposed transmission line crossing 

in 2009. Arroyo toads were not detected during surveys of the Project area in 2009. Reconnaissance 

level surveys of Little Rock Creek were conducted for arroyo toads during the 2010 breeding season. 

Toads were verified by calling near the confluence of Santiago and Little Rock creeks above the dam; 

however, toads were not detected during nighttime surveys below the dam. In addition, an inspection 

of the creek below the dam did not detect any egg masses or tadpoles. Further, it appears that habitat 

in this area has been compromised by the construction of the Little Rock Reservoir which has trapped 

sediment, altered flows, and resulted in the degradation of the stream channel below the dam. If 

arroyo toads persist below the dam, they are expected to occur in very low densities and are likely 

isolated from upstream populations. Although the proposed project transmission line route would 

cross Little Rock Creek, survey and avoidance requirements would be implemented such that there is 

little potential to affect Arroyo toad. 

Adult Arroyo toads typically require overflow pools adjacent to the inflow channel of streams that are 

generally 3rd order or greater and generally free of predators. Normally, shallow pools with sandy or 

gravely bottoms surrounded by little woody vegetation are preferred. Regular disturbance in the form 
AECOM

July 2011 Addendum to the PHPP Biological Assessment, Los Angeles County, California Page 6

of flooding is required to maintain areas of sparsely vegetated, sandy stream channels and terraces, 

which are used by adults and sub-adults for foraging and burrowing (USFWS 2001; CEC 2010). This 

type of suitable habitat does not occur along Alternative Route 4. Therefore, construction or 

operation of Alternative Route 4 would have no effect on Arroyo toad. 

Assessment of Potential Impacts, Road Paving

Desert Tortoise

Surveys for desert tortoise have not been conducted for the proposed road segments, and this 

species may occur along portions of road segments 1, 3, 5, and 10. The majority of the proposed 

roads, however, are located in existing urban residential areas where the surrounding habitat is 

disturbed. Desert tortoise has a very low potential to occur near the proposed roads identified in Table 

2 (CEC 2011a). 

As mentioned above related to Alternative Route 4, Conditions of Certification will be contained in the 

Final PHPP Decision (anticipated to be approved in August 2011) that apply to protection of desert 

tortoise and other biological resources in and near the PHPP. These conditions will also apply to road 

paving activities. Therefore, paving any of the identified road segments is expected to have 

insignificant impacts on desert tortoise. 

Arroyo Toad

No suitable habitat for the arroyo toad occurs in the proposed roads paving area locations. As noted 

above, focused presence/absence surveys were conducted in suitable habitat for the Applicant’s 

proposed transmission line route with negative results. Mitigation has not been proposed for potential 

impacts to arroyo toad during PHPP road paving due to the absence of suitable habitat in the Project

impact area or vicinity. Similar to the Alternative Route 4, since suitable habitat for Arroyo toad (as 

described above) is not found in the vicinity of these road segments, no impact to the species 

is expected from the road paving.

Determination of Effects

Desert Tortoise

Implementation of Alternative Route 4 or the road paving as described may affect but is not likely to 

adversely affect the desert tortoise. The proposed Project area and associated features are primarily 

located within disturbed, developed, and fragmented urban areas. Because of this structural spatial 

arrangement, habitat conditions are sub-prime for tortoise activity.

Arroyo Toad

Implementation of Alternative Route 4 or the road paving will have no effect to the arroyo toad or 

arroyo toad critical habitat, since suitable habitat does not occur where these project components 

would be located. Comprehensive surveys have not revealed the presence of the species within the 

Project area, and habitat is absent from these additional project components. 
AECOM

July 2011 Addendum to the PHPP Biological Assessment, Los Angeles County, California Page 7

Addendum to the Palmdale Hybrid Power Project Biological As s es s ment –

Figure 1: Proposed Transmission Line Alternative Route 4 (CEC 2010)
AECOM

July 2011 Addendum to the PHPP Biological Assessment, Los Angeles County, California Page 8

Addendum to the Palmdale Hybrid Power Project Biological As s es s ment –

Figure 2.a: Potential Road Segments for Paving (CEC 2011c)
AECOM

July 2011 Addendum to the PHPP Biological Assessment, Los Angeles County, California Page 9

Addendum to the Palmdale Hybrid Power Project Biological As s es s ment –

Figure 2.b: Potential Road Segments for Paving (CEC 2011c)
AECOM

July 2011 Addendum to the PHPP Biological Assessment, Los Angeles County, California Page 10

References

AECOM, 2009a. S. Head (tn: 51347). PSD Application and Draft Biological Assessment. Submitted to 

EPA on 3/31/09 and to the CEC Docket Unit on 4/29/09.

AECOM, 2009b. PHPP Responses to CEC Data Request Set 2 (91-162) and Supplemental 

Response to #4 to CEC Data Request Set 1, May 1.

AMEC Earth & Environmental, Inc., 2008. Palmdale Hybrid Power Project Biological Resources 

Technical Report. Prepared for ENSR Corporation (AECOM). July.

California Energy Commission (CEC), 2011a. Energy Commission Staff's Rebuttal Testimony. 7 pp 

and Table 1.

CEC, 2011b. PHPP Presiding Member’s Proposed Decision. June.

CEC, 2011c. Palmdale Hybrid Power Project – Location of Potential Roads for Paving. 

CEC, 2010. PHPP Final Staff Assessment. December.

City of Palmdale, 2008. Application for Certification for the Palmdale Hybrid Power Project. Dated 

7/30/08. Placed in the CEC/Docket Unit on 8/4/08.

Holland, D.C., and N.R. Sisk. 2001. Habitat use and population demographics of the arroyo toad (Bufo 

californicus) on MCB Camp Pendleton, San Diego County, California 1998-2000. AC/S 

Environmental Security, Wildlife Management Branch. Contract No. M 00681-97-C-0034.

Griffin, P.C. and T.J. Case. 2001. Terrestrial habitat preferences of adult arroyo southwestern toads.

Journal of Wildlife Management. 65(4): 633-644.

United States Fish & Wildlife Service (USFWS). 1999. Arroyo southwestern toad (Bufo micoscaphus

californicus) recovery plan. U.S. Fish and Wildlife Service, Portland, Oregon. vi + 119 pp.

USFWS. 2001. Endangered and Threatened Wildlife and Plants; Final Designation of Critical Habitat 

Listing for the Arroyo Toad. Federal Register Vol. 66, No. 26.