West Mojave Plan FEIR/S - Desert Managers Group

tortoises are either extirpated (Lancaster, western Palmdale, southern Apple Valley, central andeastern Victorville, all of Hesperia) or very nearly so (remaining areas) 11 .Indirect effects of urbanization are less clear than the direct effects of mechanicallyremoving 10 acres of occupied tortoise habitat, but, cumulatively, they remove tortoises from thelandscape as effectively as heavy equipment. Wide-spread dumping, sheep grazing, unregulatedoff highway vehicle traffic, release of hazardous materials (i.e., motor oil drained on the ground,discarded paint, etc.), tortoise collection, loss of tortoises and habitat degradation by feral and petdogs, and increased raven numbers are just a few of the impacts associated with urbanization thatextend far into the desert. Where residential communities are immediately adjacent to tortoisehabitat (Barstow, northern Lucerne Valley, Silver Lakes/Helendale, Hinkley, Twentynine Palms,etc.) the impact may be even more threatening to core aggregations of tortoises.Between 1990 and 2001, LaRue surveyed 78 different project sites in urbanizing areas forevidence of tortoises. Urbanizing areas included in the survey, among others, were AppleValley, Baldy Mesa, Barstow, California City, Hesperia, Joshua Tree, Lake Los Angeles,Lancaster, Landers, Lucerne Valley, Newberry Springs, Palmdale, Phelan, Ridgecrest,Rosamond, Silver Lakes/Helendale, Victorville, Yermo, and Yucca Valley. Table 3-16 reportsthe prevalence, in descending order, of observable direct impacts associated with these (andother) urbanizing areas.Table 3-16Disturbances Observed on 78 Projects in Urbanizing AreasDISTURBANCE CATEGORY NUMBER OF PROJECTS WITHDISTURBANCEDISTURBANCE ON 100% OFTRANSECTSCross-country OHV travel 74 (95%) 39 (50%) project sitesDumping 72 (92%)Domestic dog sign 69 (88%) 20 (26%) project sitesDirt roads 67 (86%) 28 (36%) project sitesShotgun shells 59 (76%)Misc. ground disturbance 24 (31%)Evidence of sheep grazing 19 (24%)Cross-country OHV tracks, dumping, domestic dog sign, and dirt roads are prevalent inthese urbanizing areas. The third column reports the number and percentage of the 78 siteswhere the indicated disturbance was observed on 100% of transects surveyed. Thus, 39 of the 78projects (50%) had vehicle tracks, 28 of 78 (36%) had dirt roads, and 20 of 78 (26%) had dogsign on 100% of all transects surveyed.These data are comparable to those collected by LaRue and others in 1991 in the 225 mi 2Lancaster planning area, where tortoises historically occurred but are now extirpated (TierraMadre Consultants, Inc. 1991). In that study, aerial photographs revealed that only 90 of the 22511 Each of the following reports has identified extensive areas where tortoises no longer occur: (a) 225 square milesof Lancaster (Tierra Madre Consultants, Inc. 1991); (b) 200 square miles encompassing portions of Adelanto, AppleValley, Hesperia, and Victorville (Tierra Madre Consultants, Inc. 1992); (c) 100 square miles of Palmdale(Feldmuth and Clements 1990); and (d) 38 square miles of Ridgecrest and Inyokern (Circle Mountain BiologicalConsultants 1997).Chapter 3 3-97