BIOLOGICAL RESOURCES

Would the project have:	Potentially Significant Impact	Less-Than-Significant With Mitigation Incorporated	Less-Than-Significant Impact	No Impact
a) Have a substantial adverse effect, either directly or through habitat modifications, on any species identified as a candidate, sensitive, or special status species in local or regional plans, policies, or regulations, or by the California Dept. of Fish and Game or U.S. Fish and Wildlife Service?	.	.	x	.
b) Have a substantial adverse effect on any riparian habitat or other sensitive natural community identified in local or regional plans, policies, regulations or by the California Dept. of Fish and Game or U.S. Fish and Wildlife Service?	.	.	.	x
c) Have a substantial adverse effect on federally protected wetlands as defined by Section 404 of the Clean Water Act (including, but not limited to, marsh, vernal pool, coastal, etc.) through direct removal, filling, hydrological interruption, or other means?	.	.	.	x
d) Interfere substantially with the movement of any native resident or migratory fish or wildlife species or with established native resident or migratory wildlife corridors or impede the use of native wildlife nursery sites?	.	.	.	x
e) Conflict with any local policies or ordinances protecting biological resources, such as a tree preservation policy or ordinance?	.	.	.	x
f) Conflict with the provisions of an adopted Habitat Conservation Plan, Natural Community Conservation Plan, or other approved local regional, or state habitat conservation plan?	.	.	.	x

ENVIRONMENTAL SETTING
The MGS is located in the extreme southern portion of Nevada in Clark County at an elevation of approximately 700 feet. The facility includes a generating complex on approximately 2,490 acres. The station is located approximately one mile west of the Colorado River adjacent to Bullhead City, Arizona.

The vegetation community at and surrounding the MGS consists primarily of southern desert shrub. Dry washes associated with the southern desert shrub habitat drain away from the generating facility towards the Colorado River (SCE 1999). Other on-site habitats include open water (evaporation ponds) and developed land. A description of the on-site vegetation communities and habitats is presented below, along with the dominant plant and wildlife species most likely associated with these habitats. This description is based on the Las Vegas Resource Management Plan prepared by the BLM for the Las Vegas BLM District (1998). This district includes approximately five million acres and encompasses all of Clark County and the southern portions of Nye and Lincoln Counties. Additionally, special status plants and animals occurring in the vicinity of the project site and their potential for occurring within the project boundaries are described.

Vegetation and Wildlife

Southern Desert Shrub. The dominant vegetation community at the MGS is southern desert shrub (SCE 1999). This vegetation community is typically found at elevations below 4,000 feet where annual rainfall is unpredictable, usually averaging less than 6 inches per year. The primary plant species is creosote bush, with white bursage as a codominant species. The creosote bush overstory is very open, as the individual plants are widely spaced, representing an overall plant cover of less than 20 percent. The understory of this community is mostly bare ground with sparsely scattered common forbs and grasses, including Indian ricegrass, Russian thistle, big galleta, desert needlegrass, and filaree. The dry washes found at the site area are typical of the southern desert shrub at the lower elevation range and usually support catclaw acacia (SCE 1999).

The southern desert shrub community provides habitat for many species adapted to arid conditions. Reptiles are particularly well suited to survive the extreme conditions of this habitat. Reptile species expected within this community include the desert horned lizard, desert spiny lizard, long-tailed brush lizard, side-blotched lizard, common kingsnake, sidewinder, western whiptail, and Mojave rattlesnake. Common resident and migratory birds utilizing this habitat for food, cover, and nesting most likely include the ash-throated flycatcher, verdin, northern mockingbird, black-throated sparrow, house finch, black-tailed gnatcatcher, turkey vulture, and common raven. Mammal species expected in the site vicinity may include the round-tailed ground squirrel, kangaroo rat, deer mouse, coyote, long-tailed pocket mouse, little pocket mouse, desert cottontail, black-tailed hare, and feral burro.

Open Water Habitat. There are a number of evaporation ponds that receive wastewater from the cooling facilities at the MGS. Although such areas are considered low quality wildlife habitat, these aquatic features most likely attract common waterbirds such as mallards, killdeer, and American coots for foraging and nesting areas. These ponds may also provide foraging and drinking areas for common mammals such coyotes, raccoons and skunks (SCE 1999).
Developed/Disturbed. A portion of the project site is developed or heavily disturbed with roads, buildings, tanks, and other features. These areas are not landscaped and do not provide suitable habitat for native wildlife species.

Special Status Species
The BLM has identified a number of special status species that occur in the southern part of Nevada. Special status species include plants and animals listed, proposed, or candidates for listing under the federal Endangered Species Act (FESA), state-listed, and BLM-sensitive species. Table 4.4-1 contains a list of special status species found in the Las Vegas BLM District, their legal status, and their potential for occurrence on the MGS site. The following section briefly highlights those special status species that could potentially occur on the MGS site.

Plants. Within the Las Vegas BLM District, eight plant species are either federally listed as threatened or endangered or are candidates under FESA (Table 4.4-1). These eight species are also listed as critically endangered by the State of Nevada. The suitability of the undisturbed portions of the site for listed plant species has not been determined. Additionally, there are 36 other species that are considered special status species by the BLM, all of which are listed as critically endangered by the State of Nevada. None of the latter species have been documented as occurring in the Las Vegas BLM District and are thus presumed absent from the MGS site (SCE 1999).

Amphibians. Suitable habitat does not occur within the MGS property boundary for any of the special status amphibians listed on Table 4.4-1 (SCE 1999).

Reptiles. Desert Tortoise. The desert tortoise is a federally listed threatened species that is a year-round resident within the Las Vegas BLM District. This species usually occurs in creosote-bursage or creosote-yucca communities below 5,000 feet. Approximately three million acres of desert tortoise habitat occurs on BLM lands in Clark and Nye Counties. After the desert tortoise was listed under the Federal Endangered Species Act (FESA) in 1989, Clark County prepared a Short-Term Habitat Conservation Plan for desert tortoise in conjunction with other local governments to obtain a Section 10(a)(1)(B) permit allowing incidental take of desert tortoise on private land. As mitigation for incidental take on private land, the Piute Valley/Eldorado Tortoise Management Area was established in the southern part of Clark County. The Section 10(a)(1)(B) permit associated with the Short-Term Habitat Conservation Plan expired on July 31, 1995, and was replaced by a long-term plan (the Clark County Desert Conservation Plan) and associated incidental take permit. This plan addresses implementation of the Tortoise Recovery Plan in Clark County and, under this plan and the associated permit, all private land owners in Clark County are covered for incidental take (BLM 1998). Evidence of the presence of desert tortoises has been found on-site, although the population density is likely to be low (SCE 1999). The Clark County Desert Conservation Plan may be replaced by the Clark County Multiple Species Habitat Conservation Plan (the MSHCP), which would cover the desert tortoise and numerous other special status species.

BIRDS

Ferruginous Hawk. The ferruginous hawk is a BLM sensitive species and federal species of special concern that frequents open grasslands, sagebrush flats, and desert scrubs. This species typically does not nest within the Las Vegas District, but nesting could occur in the project area during winter (SCE 1999).

Table 4.4-1: Special Status Vertebrate Species Potentially Occurring in the MGS Project Region.

Species	Status	Potential for Occurrence
FISH
Woundfin minnow (Plagopterus argentissimus)	FE	Presumed absent due to a lack of suitable habitat.
Bonytail chub (Gila elegans)	FE	Presumed absent due to a lack of suitable habitat.
Colorado squawfish (Ptychocheilus lucius)	FE	Presumed absent due to a lack of suitable habitat.
Razorback sucker (Xyrauchen texanus)	FE	Presumed absent due to a lack of suitable habitat.
AMPHIBIANS
Arizona southwestern toad (Bufo microscaphus microscaphus)	FSC,BSS	Presumed absent due to a lack of suitable habitat.
Relict leopard frog (Rana pipiens fisheri)	E	Presumed absent due to a lack of suitable habitat.
REPTILES
Desert tortoise (Gopherus agassizii)	FT	Presumed present at low densities within suitable on-site habitat.
Chuckwalla (Sauromalus obesus)	BSS	Presumed absent due to a lack of suitable habitat.
Gila monster (Heloderma suspectum)	SR	Presumed absent due to a lack of suitable habitat.
BIRDS
Bald eagle (Haliaeetus leucocephalus)	FT	Presumed absent due to a lack of suitable habitat.
Ferruginous hawk (Buteo regalis)	FSC, BSS	May occur within suitable on-site habitat.
Peregrine falcon (Falco peregrinus anatum)	SE	No nesting habitat. May move through the site.
Southwestern willow flycatcher (Empidona trailii extimus)	FE	Presumed absent due to a lack of suitable habitat.
Western burrowing owl (Athene cunicularia hypugea)	FSC, BSS	May occur within suitable on-site habitat.
Phainopepla (Phainopepla nitens)	BSS	May occur within suitable on-site habitat.
MAMMALS
Greater western mastiff-bat (Eumops perotis californicus)	FSC, BSS	Presumed absent due to a lack of suitable roosting habitat.
Allen’s big-eared bat (Idionycteris phyllotis)	FSC, BSS	Presumed absent due to a lack of suitable roosting habitat.
California leaf-nosed bat (Macrotus californicus)	FSC, BSS	Presumed absent due to a lack of suitable roosting habitat.
Small-footed myotis (Myotis ciliolaburm)	FSC, BSS	Presumed absent due to a lack of suitable roosting habitat.
Long-eared myotis (Myotis evotis)	FSC, BSS	Presumed absent due to a lack of suitable roosting habitat.
Fringed myotis (Myotis thysanodes)	FSC, BSS	Presumed absent due to a lack of suitable roosting habitat.
Cave myotis (Myotis velifer)	FSC, BSS	Presumed absent due to a lack of suitable roosting habitat.
Long-legged myotis (Myotis bolans)	FSC, BSS	Presumed absent due to a lack of suitable roosting habitat.
Yuma myotis (Myotis yumanensis)	FSC, BSS	Presumed absent due to a lack of suitable roosting habitat.
Big free-tailed bat (Nyctinomops macrotis)	FSC, BSS	Presumed absent due to a lack of suitable roosting habitat.
Pale Townsend’s big-eared bat (Plecotus townsendii paliescens)	FSC, BSS	Presumed absent due to a lack of suitable roosting habitat.
PLANTS
Ash Meadows milkvetch (Astragalus phoenix)	FT, SCE	Habitat suitability not determined. Presumed absent from developed areas.
Ash Meadows milkvetch (Astragalus phoenix)	FT, SCE	Habitat suitability not determined. Presumed absent from developed areas.
Spring-loving centuary (Centaurium namaphilum)	FT, SCE	Habitat suitability not determined. Presumed absent from developed areas.
Ash Meadows sunray (Enceliopsis nudicaulis var. corrugata)	FT, SCE	Habitat suitability not determined. Presumed absent from developed areas.
Ash Meadows gumplant (Grindelia fraxino-pratensis)	FT, SCE	Habitat suitability not determined. Presumed absent from developed areas.
Ash Meadows ivesia (Ivesia kingi var. eremica)	FT, SCE	Habitat suitability not determined. Presumed absent from developed areas.
Ash Meadows blazing star (Mentzelia leucophylla)	FT, SCE	Habitat suitability not determined. Presumed absent from developed areas.
Ash Meadows niterwort (Nitrophila mohavensis)	FT, SCE	Habitat suitability not determined. Presumed absent from developed areas.
Blue diamond cholla (Opuntia whipplei multigeniculata)	FT, SCE	Habitat suitability not determined. Presumed absent from developed areas.

SOURCE: SCE 1999

Legend
FE = Federal endangered species
FT = Federal threatened species
FC = Federal candidate species
FSC = Federal species of concern; such species have no protection under FESA
SE = Species protected under NRS 501
SR = State of Nevada rare species
SCE = State of Nevada critically endangered
BSS = BLM sensitive species
E = Presumed extinct


Peregrine Falcon. The peregrine falcon has been recorded along the Colorado River drainage from the Overton State Wildlife Management Area south to Lake Mead, in Red Rock Canyon, in the Pahrump Valley, in the Desert National Wildlife Range and in the Christmas Tree Pass area (SCE 1999). Although this species occurs along the Colorado River and is known to nest in the project area, suitable nesting habitat does not occur on the MGS site. Peregrine falcons may move through the undeveloped portions of the project site. The peregrine falcon was delisted by the USFWS in 1999.

Western Burrowing Owl. The western burrowing owl is a BLM sensitive species and federal species of special concern that is found in southern Nevada. This species nests within the project vicinity during the breeding season and migrates south to the United States border and Mexico during the winter. Burrowing owls utilize burrows constructed by other animals, such as desert tortoises, badgers, and ground squirrels, in open grasslands and shrublands (SCE 1999). This species could potentially occur within the MGS property boundary.

Phainopepla. The phainopepla is a BLM sensitive species occurring in open woodlands, shrubs, and chaparral; however, the highest densities are found in desert washes and desert riparian habitats. Individuals nesting in deserts disperse from early May to September, moving to more western and northern parts of their range. This species could potentially occur in the dry washes associated with southern desert shrub community on the project site (SCE 1999).

Special Status Mammals. The USFWS has identified 11 species of bats potentially occurring in the Las Vegas BLM District (Table 4.4-1). Although there is little information on the status and distribution of these species, their occurrence is most likely associated with roosting and brooding sites in caves, crevices, and abandoned mine tunnels.

Although many of these species could forage in the Las Vegas BLM District, the lack of on-site roosting and brooding habitats most likely precludes these species from the MGS (SCE 1999).

ENVIRONMENTAL IMPACTS

Sale of the MGS
a), b), c), d), e), f) Sale of the MGS itself would not result in any physical changes to the environment because it would only change the owner of the MGS. The sale would therefore not result in any impacts to biological resources.

Construction of 500 feet of Fencing
a) The area where the new fencing is proposed is within the portion of the MGS site that has been compacted and disturbed in the past. There is no vegetation in the area where the new fence is proposed. Although the area has been disturbed, a small chance exists that construction of the fence may impact the desert tortoise. Construction of the fence would require a permit from Clark County that includes a fee for the applicable HCP. The fee acts as mitigation for habitat lost through fence construction. The Western Burrowing Owl is unlikely to be encountered in the area where the fence is located because it is graded, impacted, and heavily used.

b) There is no riparian habitat or other sensitive natural community in the area where the fence would be constructed. Therefore, the project would have no impacts on riparian habitat or other sensitive natural communities.

c) There are no wetlands in the area where the fence is proposed. Therefore, the project would have no impacts on wetlands.

d) The proposed fence site is within an already developed power plant site that has been fenced. The power plant may interfere with movement or migration of species. No species is known or expected to migrate across the MGS site, except the Peregrine Falcon, which is not restricted in movement by a fence. Construction of the 500 feet of fence within the already fenced-in MGS boundary would not create additional interference with the migration or other movement of any species. No native wildlife nurseries exist at the fence site, and none would be impacted by fence construction.

e) No local policies have been identified with which the construction of 500 feet of fence at an existing power plant would be in conflict.

f) Construction of the fence would not conflict with provisions of the Clark County Desert Conservation Plan because the plan allows for such development. Any mitigation implemented for impacts to desert tortoises would be in conformance with applicable provisions of that plan or the MSHCP, if then in effect.

Continued Existing Operations
a), b), c), d), e), f) Continuation of existing operations would not have any new physical impacts on the environment. Continued existing operations would therefore not result in any impacts to biological resources.

Increased Plant Output by Approximately 10%
a) Increased output at the MGS would result in a more intense use of the MGS, but any facility changes would occur in already developed areas. Therefore, increasing plant output would not impact any special status species.
Increased plant output would also result in a small increase in air emissions. The plant is already permitted to operate at an increased rate, however, and the added air emissions would be within permitted levels. Even with increased output, eventual installation of the scrubber and bag house will reduce emissions to below present levels. The temporary increase in emissions would not result in impacts on special status plants and animals in the project area.

b) There is no riparian habitat or other sensitive natural community in the area where the power plant is located. Therefore, increasing plant output would have no impacts on riparian habitat or other sensitive natural communities.

c) There are no wetlands in the area where the power plant is located. Therefore, increasing plant output would have no impacts on wetlands.

d) Increasing plant output may result in an increase in the intensity of use within the MGS site, but no species is known or expected to migrate across the MGS site that would be restricted in movement by a fence. The power plant site is developed and fenced. Although the presence of the plant and associated fencing may already interfere with movement or migration of species, increased intensity of use within that fenced area would not create additional barriers to animal migration or other movement. Therefore, increasing plant output would have no impacts on animal movement. No native wildlife nurseries exist at the MGS site, and none would be impacted by increased intensity of its use.

e) The MGS is already permitted to operate at an increased rate. No local policies have been identified with which the increased intensity of use would be in conflict.

f) Increased plant output within permitted parameters would not conflict with provisions of the Clark County Desert Conservation Plan or the MSHCP because the site has already been developed as a power plant.

MITIGATION MEASURES
None required.

CULTURAL RESOURCES

Would the proposal have:	Potentially Significant Impact	Less-Than-Significant With Mitigation Incorporated	Less-Than-Significant Impact	No Impact
a) Cause a substantial adverse change in the significance of a historical resource as defined in CEQA Guidelines §15064.5?	.	.	.	x
b) Cause a substantial adverse change in the significance of an archaeological resource pursuant to CEQA Guidelines §15064.5?	.	x	.	.
c) Directly or indirectly destroy a unique paleontological resource or site or unique geologic feature?	.	.	.	x
d) Disturb any human remains, including those interred outside of formal cemeteries?	.	x	.	.

ENVIRONMENTAL SETTING
A search of the records for the Nevada Office of Historic Preservation was conducted in December 1998. The results of this search indicate that either no cultural resources have been identified from previous inventory efforts or no inventories have been conducted within the MGS plant site boundaries. It is presumed from this records search that the archaeological and paleontological surveys conducted by Brooks et al. (1974, 1975) and McClellan (1974a, 1974b) are the only cultural resource surveys for this property to date.
According to the Nevada Office of Historic Preservation, it is likely that significant archaeological, and possibly traditional cultural properties, may be present within the MGS plant boundaries. The paleontological sensitivity of the plant site is expected to be low.

Archaeological Resources
Cultural resources are the tangible remains of past human activities. The MGS is situated within a unique region located adjacent to the Colorado River at the interface of three distinct geographic zones: (1) Colorado Plateau, (2) Mojave Desert, and (3) Great Basin. Each zone shows evidence of the distinctive Native American groups who adapted to the natural resources of the area. In an otherwise arid environment, the Colorado River was a "magnet" for prehistoric human occupation. Consequently, archaeological sites comprised of the material remains of prehistoric peoples are particularly abundant along and in the near vicinity of the Colorado River.

Prehistoric cultural sequences and a cultural chronology applicable to the Mohave project area are given in Warren and Crabtree (1986). They present a chronological and cultural framework extending back in time about 11,000 to 12,000 years before present (YBP), to the point of the arrival of the first recognized peoples into North America and this region. The material remains of these and later peoples, preserved in archaeological contexts, have been given the various labels of Clovis, Lake Mojave, Pinto, Gypsum Cave, Saratoga Springs, Shoshonean, and others depending on the place of discovery and preference of the reporting researcher. In general, these cultural and chronological sequences document the adaptation of the various human groups that utilized the desert and its margins to the changing environment and social conditions.

At the time of European contact, Mohave Valley (the location of the MGS) was within the traditional territory of tribes of the Yuman (Hokan) speaking Mojaves. Mojave lands stretched along the Colorado River from the site of Hoover Dam southward to approximately 100 miles below Parker Dam (Sherer 1965). Within the Mojave nation were three subgroups: the northern, central, and southern. The great chieftain of the Mojave in 1859 was also the hereditary chief of the northern subgroup. This subgroup’s territory was between Boulder Dam (Black Canyon) and the head of Mohave Valley. The central group occupied Mohave Valley; the southern group occupied the area south of Needles Peaks (Sherer 1966). Each of these subgroups had chiefs, with the central group having five in 1859. At that time, there was a total of seven chiefs in all.

The Mojave subsisted by flood water agriculture along the Colorado River, and by hunting and gathering in that area and in the adjacent territories. The Mojaves were famous as travelers and warriors.
The two places that serve as most sacred in Mojave oral literature are Aha’av’ulypo and Avikwame. Aha’av’ulypo, (Housepost water) is in Eldorado Canyon north of Mohave Valley (Kroeber 1925). Avikwame is within the Newberry Mountains (located about 10 miles northwest of the MGS) which, according to Mojave myth, was created by the hero Mastamho who completed the creation process from that location and built himself a house there. Mojave shamans dream of Mastamho’s house on Avikwame, where their shadows received power from Mastamho in the time of the beginnings (Kroeber 1925). Consequently, Avikwame is a place of great power and sacredness (Bean and Vane 1982).

The visit of the Oñate expedition to the Mojave villages in 1604, and that of Garcés in 1776, and subsequent events brought the Mojave into the mainstream of southwestern history in the mid-19th century. The potential for encountering hostile Mojaves influenced the establishment of east/west travel routes that bypassed their territory until the 1850s, when a series of conflicts between Mojaves and Anglo-Americans resulted in the establishment of Fort Mojave in 1859 near the bend of the Colorado River (just south of the MGS) (Bean and Vane 1982). Fort Mojave was abandoned in 1861 at the start of the Civil War and regarrisoned in 1865; it was occupied until 1890, when it was transformed into a boarding school for Indian children (Bean and Vane, 1982). In 1910-1911, the 14,000 acres that belonged to the old Fort Mojave military post, and an additional 17, 328 acres, were set aside as the Fort Mojave Reservation by Executive Order (Sherer 1966).

Documented archaeological survey of the MGS plant site is restricted to two transmission line corridors that : Mohave-Eldorado and Mohave-Pisgah (Brooks et al. 1974). No archaeological resources were recorded within these areas. The presence or absence of archaeological resources or traditional cultural properties within the remainder of the plant site is unknown.

Historical Resources
The first European contact with Mojave peoples were members of a Spanish expedition led by Juan de Oñate, which in 1604, descended the Bill Williams Fork to the Colorado River. Part of this expedition visited a Mojave village, apparently in Mohave Valley (Bolton 1926). In 1776, Franciscan friar Francisco Garcés visited Mojave villages in Mohave Valley, noting the native agriculture. Native resistance to Spanish encroachment along the Colorado River culminated in the Yuma uprising of 1781, when the Yuman peoples destroyed the Spanish settlements and openly declared their animosity to outsiders (Forbes 1965).

The first Anglo-Americans to pass through Cottonwood and Mohave Valley were a party of fur trappers led by Jedediah Smith in 1826; this interaction was relatively friendly (Brooks 1977). The passing of another group of trappers led by Ewing Young in 1827 angered the Mojaves into defensive military action at the Colorado River, and when Smith returned with a second expedition later that year, his group was attacked by the Mojave, who killed 11 of his 20 man group. In 1829-1830, a trapper led by Peter Ogden fought a battle with Mojaves that resulted in 26 Mojave deaths (Casebier 1975). These hostilities on the Colorado River were widely publicized and the reputation of the Mojaves as a fierce and hostile group spread across the continent. As a result, overland westward travel was deflected northward around the Mojave territories along what became known as the "Old Spanish Trail." A variation of this route established by Mormons from Utah emigrating to San Bernardino in 1851 was called the "Mormon Trail" (Hoover et al. 1966).

An expedition led by Lt. Lorenzo Sitgreaves of the U.S. Army Corps of Topographic Engineers visited the Mojave villages in 1851 and also encountered hostilities (Sitgreaves 1853). However, when Lt. Amiel Whipple led another military survey group through this territory in 1854, he was able to maintain good relations with the Mojaves (Whipple 1856). In 1858, Edward Beale recommended that a military post be established on the Colorado River to protect travelers (Lesley 1929). Subsequent Anglo-Mojave hostilities resulted in the establishment of Fort Mojave in 1859.

Precious metal mines were established in the general area by the early 1850s. One of the most productive mines was in Crescent (west of Searchlight). Between 1863 and 1878, Mexican miners are said to have extracted more than $500,000 in gold from this area (Paher 1970). First gold and then silver was discovered and mined in Eldorado Valley between 1857 and the 1890s (Myrick 1963). Mining of various minerals continues to the present in the region, depending on the economy and market for these materials.

Historic use of this area was primarily focused on transportation beginning with the prehistoric Mojave Trail, of which one branch became the Mojave Road in the 1860s and 1870s. In the 1880s, the Santa Fe Railroad was built through the Mojave Desert and followed soon after by the Atlantic & Pacific Rail Line, which crossed the Colorado River at Needles (Casebier 1976). Settlements developed along the railroads in strategic locations. With the advent of the automobile and its more common use in the early 20th century, roads (i.e., the historic National Trails Highway/Route 66) encouraged additional settlement to support the motoring public.

Construction of Hoover Dam in the 1930s and Davis and Parker Dams in the 1940s brought in large numbers of construction workers, established communities that persist to the present, and provided water for agricultural irrigation, lakes for flood control, and generated a sense of the recreation potential of this region that contributed significantly to the modern economy and land use patterns. The retirement and recreation developments in the vicinity of the MGS are a reflection of this land use.
Documented historical survey of the MGS plant site is restricted to two transmission line corridors: Mohave-Eldorado and Mohave-Pisgah (Brooks et al. 1974). No historic resources were recorded within these areas. The presence or absence of historic resources within the remainder of the plant site is unknown.

Paleontological Resources
Paleontological resources are the fossilized remains of plants and animals. Fossils are unique, non-renewable resources that provide clues to the history of life on earth; as such, fossils have scientific value.

According to McClellan (1974), the MGS area is underlain by Precambrian granites and gneisses (exposed in the Newberry Mountains near Davis Dam on the west side of the Colorado River), Pleistocene non-marine clastic material consisting of old alluvial fans, valley fill, and river deposits representing the Chemehuevi Formation and unnamed equivalents, and unconsolidated recent alluvium. The MGS plant site is probably mostly Chemehuevi Formation covered in places by recent alluvium. Fossils have been recovered from the Chemhuevi Formation in the vicinity of Davis Dam consisting of Pleistocene elephant and bison remains (McClellan 1974). This formation is most likely to produce fossil remains within boundaries of the MGS. The Pre-Cambrian granites and gneisses and the recent alluvium have no paleontological sensitivity.

Documented paleontological survey has not been undertaken on the MGS plant site except within the Mohave-Eldorado and Mohave-Pisgah transmission line corridors (McClellan 1974a, 1974b). No fossils were recorded within the plant site boundaries. The sensitivity of the Chemehuevi Formation within the plant site, the extent to which it is exposed, or the depth to which it may be encountered, is unknown.

ENVIRONMENTAL IMPACTS

Sale of the MGS
a), b), c), d) The sale of the MGS would not, in and of itself, result in physical changes and would therefore not result in impacts to cultural resources.

Construction of 500 feet of Fence
a) The construction of a fence would not impact historical resources as defined in CEQA Guidelines §15064.5, because no historic resources exist within the proposed fence area.

b) The proposed fence installation area is predominately disturbed land that has been used for various industrial purposes. Additionally, fence installation does not require the excavation of large amounts of soil. If construction activities such as excavation or drilling are involved in the installation of the fence, however, impacts such as the disturbance of buried archaeological resources could arise. This potential impact will be mitigated to a level of insignificance with the imposition of the mitigation measure below.
c) The construction of a fence would not impact paleontological or geologic features, because none are known or expected to exist within the proposed fence area.

d) The proposed fence installation area is predominately disturbed land that has been used for various industrial purposes. Additionally, fence installation does not require the excavation of large amounts of soil. If construction activities such as excavation or drilling are involved in the installation of the fence, however, impacts such as the disturbance of human remains could arise. This potential impact will be mitigated to a level of insignificance with the imposition of the mitigation measure below.

Continued Existing Operations
a), b), c), d) Continuation of existing operations not result in impacts to cultural resources because no physical changes would occur.

Increased Plant Output by Approximately 10%
a), b), c), d) Increased plant output would not impact cultural resources because new surface disturbance or substantial excavations would not be expected to occur.

MITIGATION MEASURE

Construction of 500 feet of Fence

If digging is required to install the fence, work areas shall be monitored during construction by a qualified archaeologist. If cultural resources are identified, construction or excavation activities shall be temporarily halted or directed to other areas, pending the archaeologist’s evaluation of the resources’ significance. The materials and site shall be recorded using standard archaeological survey methods. The site shall be evaluated by a qualified archaeologist for its significance in consultation with the Nevada Department of Historical Preservation and Archaeology. If significant resources are found, the site shall be avoided or a data recovery plan shall be developed and implemented to ensure that the information contained in the site is not lost. If the site is determined to not be significant, no further action is required.

If human remains are encountered, the archaeologist shall contact the appropriate County Coroner immediately, and security measures shall be implemented to ensure that burials are not vandalized. No further construction disturbance of the site shall occur until the decision of disposition has been made and implemented pursuant to applicable law.

GEOLOGY AND SOILS

Would the project have:	Potentially Significant Impact	Less-Than-Significant With Mitigation Incorporated	Less-Than-Significant Impact	No Impact
a) Expose people or structures to potential substantial adverse effects, including the risk of loss, injury, or death involving:	.	.	.	X
i. Rupture of a known earthquake fault, as delineated on the most recent Alquist-Priolo Earthquake Fault Zoning Map issued by the State Geologist for the area or based on other substantial evidence of a known fault? Refer to Division of Mines and Geology Special Publication 42.	.	.	.	X
ii. Strong seismic ground shaking?	.	.	.	X
iii. Seismic-related ground failure, including liquefaction?	.	.	.	X
iv. Landslides?	.	.	.	X
b) Result in substantial soil erosion or the loss of topsoil?	.	.	.	X
c) Be located on a geologic unit or soil that is unstable, or that would become unstable as a result of the project, and potentially result in on- or off-site landslide, lateral spreading, subsidence, liquefaction or collapse?	.	.	.	X
d) Be located on expansive soil, as defined in Table 18-1-B of the Uniform Building Code (1994), creating substantial risk to life or property?	.	.	.	X
e) Have soils incapable of adequately supporting the use of septic tanks or alternative waste water disposal systems where sewers are not available for the disposal of waste water?	.	.	.	X

ENVIRONMENTAL SETTING

Regional Setting
The MGS is located in the Sonoran Desert section of the Basin and Range physiographic province. The station is located on the northern end of the Mohave Valley, which extends southward 30 miles to Needles, California. The oldest geologic units in the region are in the Newberry Mountains, approxi-mately three miles northwest of the site. These rocks, which underlay the MGS at depths of 1,000 to 2,500 feet, are Precambrian-age crystalline bedrock and include gneiss, schist, and granite.

Local Setting
The MGS is located on an alluvial terrace approximately 200 feet above the west bank of the Colorado River. The saturated terrace deposits consist of sands, silts, and gravels deposited by the Colorado River and alluvial fan deposits derived from the nearby Newberry Mountains. Recent geophysical investiga-tions indicate the sediments can be divided into three primary units:
• Older Fan Alluvium
• Colorado River Alluvium
• Younger Fan Alluvium

The Older Fan Alluvium deposits are the lower-most units and are comprised of multiple layers of poorly sorted and slightly compacted and cemented gravel, silt, clay, and sand. The Colorado River Alluvium overlies the older unit and consists of interbedded and well-sorted sands and gravels. The Younger Fan Alluvium overlies the site and consists of unconsolidated deposits of clays, sands, silts, and gravels. The newer materials resulted from a series of flood, channel, and alluvial fan deposits on the older erosional surfaces. The transmissivity values of the units range from moderate (approximately 200 square feet per day) in areas of silt lenses to relatively high (400,000 square feet per day) in the paleochannels of the Colorado River. Groundwater occurs at depths of 150 to 200 feet below ground surface (bgs) at the site, roughly corresponding to the elevation of the Colorado River. Regional groundwater flows to the east, but groundwater gradient at the station is to the southeast and quite flat.

Faulting and Seismicity
There are no known active faults near the MGS. Faults have been interpreted three miles north of the station in association with the Newberry Mountains. The closest known active fault, the Pinto Mountain Fault, is located 90 miles southwest of the MGS (SCE 1998). The most recent major seismic events were the October 16, 1999 Hector Mine earthquake with a magnitude of 7.1 on the Richter scale and the 1992 Lander 7.3 magnitude earthquake. These events were ample distance from the plant to reduce the ground motion sufficiently to have no impact.

Regulatory Framework
Design criteria for geologic hazards for buildings meant for human occupation, such as laboratories, offices, and control rooms, are provided in the county general plans. The plans incorporate the design standards in the Uniform Building Code (UBC) and for seismic events (Clark County Department of Comprehensive Planning 1997). Operating equipment and structures which are not intended for human occupancy are exempt from the county plans and are built to engineering and Occupational Safety and Health Administration (OSHA) construction standards.

ENVIRONMENTAL IMPACTS

Sale of the MGS
a), b), c), d), e) The sale of the MGS would not, in and of itself, result in physical changes and therefore would not result in impacts to the geology or soils of the area.

Construction of 500 feet of Fence
a), b), c), d), e) The construction of 500 feet of fence is not a large enough project to cause significant impacts to the soils or geology. The fence would not expose people or structures to potential substantial adverse effects. The total amount of soil excavated is likely to be less than a cubic yard. If fence post drilling is used it would probably not be deeper than three feet bgs and will not encounter groundwater (150 to 200 feet bgs). Fence construction would not result in substantial soil erosion or loss, would not result in other soil movement, or create any risks to life or property. The fence does not create additional waste water disposal needs.

Continued Existing Operations
a), b), c), d), e) The continuation of existing operations will not result in physical changes and therefore not result in impacts to the geology or soils of the area. The MGS is built to meet or exceed UBC, published engineering, and OSHA construction standards.

Increased Plant Output by Approximately 10%
a), b), c), d), e) Increasing the facility’s output would not result in changes that would affect the geology or soils of the area. The improvements are likely to be equipment changes within the buildings or longer operational hours and not involve structural changes or new construction. Existing waste water disposal systems would be adequate to handle any additional waste water generated by added personnel or increased output.

MITIGATION MEASURES
None required.