Three large tracts of land were bladed free of vegetation to serve as balloon launching sites for suspending vertical arrays of air sampling equipment during the 1963 Clean Slate tests at the TTR. The recovery of vegetation on these areas after 11 years was described by Wallace and Romney (1974). Again, The recovery this is Great Basin Desert, but with relatively sparse rainfall. The blading did result in resulted in an increased percentage of new grasses. some Halogeton invasion. invades overgrazed areas. This weed is poisonous to livestock and usually All these effects continue to be studied. Of special interest in the deliberations concerning alternate procedures for cleanup action are the decontamination tests made 18 years ago (in 1957) in connection with the 23%Pu safety test conducted in Area 13 (Great Basin Desert) at the NTS (Dick and Baker, 1967). These tests provide excellent background information concerning treatment effectiveness as well as land recovery 18 years following disturbance. Even though records of long-time effect were not kept, the information available is of vital importance to the present decontamination deliberations. These areas were described in some detail by Wallace and Romney (1974). The reported cleanup effectiveness of the various treatments appears in Table 2. The water-spray treatment was designed to mix the surface-deposited 739Pu into the soil sufficiently deep to decrease its resuspension hazard before the application of other decontamination operations. The test areas, which were plots 50 feet by 100 feet (15.3 x 30.6 m), were not replicated. There were 11 treatments in all. The environs of Area 13 are described as Great Basin Desert (Beatley, 1965). Because of greater rainfall and somewhat lower evapotranspiration, as mentioned earlier, revegetation under Great Basin conditions is generally more favorable than under Mojave Desert conditions (Wallace et al., 1972). The Area 13 site has somewhat less rainfall than most Great Basin Desert locations. For this reason, its recovery after 18 years has not been as great as might have been experienced elsewhere. At the present time, there is about 25% as much vegetation on the plowed site as on the undisturbed area, even less on some of the scraped sites. After 18 years, these sites are no longer grasslands, although they may have been at some intervening time. area continues to be studied. This interesting and important Some vegetation studies have been conducted in areas disturbed by contractors in preparations for underground nuclear detonations in Hot Creek Valley, Nevada (Central Nevada Supplemental Test Area). The climate of Hot Creek Valley is semiarid. The elevation of the valley floor is about 1,700 meters. Mean yearly precipitation over a 20-year period was 13.5 cm, occurring as both snow and rain. Precipitation is distributed almost evenly throughout the year (Tueller et al., 1972). Species and three seeding method trails were evaluated over a 5-year period in order to make revegetation recommendations. Findings showed that grass seeding should be made as soon as possible in the spring, preferably February or March. The reseeding studies under natural soil wetting resulted in some success, but considerable failure. Secondary invading species appeared on the disturbed areas, the most persistent of which were skeleton weed (Erigonwn deflexwn) and Russian thistle (Salsola kalti). Survival counts after 4 years indicated that pubescent wheat-grass (Agropyron trichophorum) is a most successful species of grass for use in the big sagebrush habitat type. Among the native grasses which reseeded naturally were Atlarta jamesii, Oryzopsts 70