respectively; and 28.2 + 3.8 for Area 13 (Project 57). The four sites located on TTR contained inventory estimates of 0.39 + .12, 0.54 + .27, 2.6 + .38, and 5.7 + 1.4 for Double Track, and Clean Slate 1, 2, and 3, respectively. Comparisons of soil and vegetation inventory estimates (Table 3, last column) indicate that the standing vegetation contributes an insignificant portion of the total amount of 239°240py present in these aged fallout areas. With the exception of an anomalous condition represented by the test of Area 11, Site A (which in view of the large S.E. may be unreliable), the level of contamination attri- butable to standing vegetation accounted for only one to six ten-thousandths of that estimated for soil. It seems safe to conclude, therefore, that the amounts of 239°249py in or on vegetation which are available for grazing animals is relatively small compared to the total amounts deposited in these aged fallout areas. In view of findings that the vegetation of these fallout areas is being contaminated by resuspendable materials, it seems important to consider the role that this same vegetation also plays in limiting this contamination to the low levels actually encountered. There is no doubt that vegetation acts as a windbreak against wind-driven erosional processes. It is safe to assume that the level of contamination for vegetation in these stabilized fallout areas is much less now than it would be in surrounding areas, should these sites ever become denuded. One of the best safeguards for keeping the soil contaminant in its present location within each area is to maintain the integrity of the standing vegetation. Preliminary Estimate of Uranium Inventory for Vegetation of Aged Fallout Areas Some data are given in Tables 4 and 5 concerning the average concentrations and estimated inventory of total uranium for different fallout areas. These data are preliminary in the sense that they represent only about 20 percent of the total number of vegetation samples collected for estimating inventory at the "safety test" sites. Samples to ascertain natural background have not been analyzed, so the data now presented have not been adjusted to account for that portion which might have been derived from the source material of the test devices. Updated estimates and discussion of findings will appear in future progress reports since too few data presently are available to ascertain the significance of these preliminary results and their relationship to original fallout deposition. Table 6 lists in entory estimates of the different uranium radionuclides for vegetation of Avea 11, Site A. The details of the work done at this site and some data for soil and vegetation have been reported earlier by Gilbert and Eberhardt (1975). and Gilbert et aZ. (1975b). The area sampled for Site A consisted of three strata defined on the basis of Ge(Li) scans for 235y on soil collected on a grid system. The land area represented by these three strata is about 480 m* for stratum 3; 7,700 m* for stratum 2; and 126,000 m@ for stratum 1. The total land area involved is about 134,000 m@. The contamination of vegetation samples with any radionuclide was highest for samples collected nearest ground zero in stratum 3; lowest levels of contamination were found on vegetation located farther away from ground zero in stratum 1. Summation of the amounts estimated for the different strata give 43