West Mojave Plan FEIR/S - Desert Managers Group

sites surveyed by LaRue between 1990 and 2001. These two DWMAs were chosen for theirrelative proximity to the urban and rural sites surveyed by LaRue.Table 3-19Comparison of Disturbances: DWMAs and Urbanizing AreasNUMBER (%) OF PROJECTS AND TRANSECTS WITH DISTURBANCEDISTURBANCE ON 78 SITES IN URBAN ON 1,572 TRANSECTS IN TWO DWMASCATEGORYAREASOff-road OHV tracks 74 (95%) 833 (53%)Dumping 72 (92%) 27 (2%)Domestic dog sign 69 (88%) 6 (< 1%)Dirt roads 67 (86%) 702 (45%)Shotgun shells 59 (76%) 326 (21%)Misc. ground disturbance 24 (31%) 26 (2%)Sheep grazing 19 (24%) 200 (13%)Human disturbances on the rural and urban sites surveyed by LaRue were significantlymore prevalent than the same disturbances observed in two of the proposed conservation areas.Unimproved, dirt roads (53%) and OHV cross-country travel (45%) were the two most prevalenthuman disturbances observed in the proposed conservation areas. Domestic dog sign (< 1%),dumping (2%), and miscellaneous ground disturbance (i.e., denuded and partially denuded areas)(2%) were negligible in DWMAs compared to urbanizing areas (i.e., 88%, 92%, and 31%,respectively).Maintained Roads: Trombulak and Frissell (2000) concluded that maintenance and useof roads contribute at least five different general classes of chemicals to the environment: heavymetals, salt, organic molecules, ozone, and nutrients. They found that most studies indicate thatcontamination declines within 65 feet (20 meters) but that elevated levels of heavy metals oftenoccur 650 feet (200 meters) or more from the road. However, there is no evidence thatchemicals are used on roads in the Mojave,Nor are the effects of these contaminants on tortoises known. Dr. Berry, in collaborationwith Dr. Bruce Homer, has suggested that heavy metals may be involved in the tortoise shelldisease known as cutaneous dyskeratosis. The relationship between contaminants and cutaneousdyskeratosis is not understood, nor is the lethality of the shell disease. It was associated with aregion-wide die-off of tortoises on the Chuckwalla Bench (i.e., decline from 225 tortoises in1982 to 85 in 1992), but not necessarily the cause of it. The Chuckwalla Bench die-off wascoincident with the 1988-89 die-off at the Desert Tortoise Natural Area, although 200 milesseparate the two areas.Tortoises often dig their burrows in the berms of roads, particularly along those that arenot frequently used, and where there is little vehicle stray (LaRue, pers. obs., Copper MountainMesa, between Yucca Valley and 29 Palms). An erosion ditch found along Highway 395apparently attracted at least one tortoise near that highway (LaRue 1992). Tortoises in suchburrows would be in immediate harm’s way during road maintenance that involved recontouringroad shoulders, erosion ditches, and berms.Chapter 3 3-99