The FIDLER activity strata are probably the best estimates presently available on the spatial distribution of Pu at safety-shot sites. Am and Pu in soil samples are known to be highly correlated at safety~shot sites so that Pu can be predicted fairly well from Ge(Li) Am analyses. The FIDLER is certainly a less precise predictor of Pu concentrations in 10-gram soil aliquots than are Ge(Li} scans on these soil samples in the laboratory. However, the correlation is sufficiently strong between FIDLER field readings and Pu 10-gram soil aliquot concentrations that the general pattern of surface soil Pu contamination at safety-shot sites is believed to be well estimated by FIDLER surveys. It is also true, however, that more extensive FIDLER surveys may be desirable in some or all safety-shot areas since the FIDLER strata maps are based on readings taken no closer than 25 feet, and in many cases, the spacing is 100 feet or more (see Gilbert et al., 1975, pages 343-345, for details on grid spacing). Using Kriging The Pu contours given in Gilbert et al. (1975) were estimated using a computer program called "SURFACE IL" developed by the Kansas Geological Survey. This program was applied to the Pu concentrations of 10-gram soil aliquots taken from surface (0-5 cm) soil samples at random loca- tions. SURFACE II was also used to obtain Pu concentration contours for vegetation at these locations. These initial contours were exploratory in nature and were believed to be biased in several respects. Later attempts at obtaining contours with less bias were made by Gilbert (1976b; also this publication), who used iterative techniques in conjunction with SURFACE II; and by Barnes et aZ. (1977) and Delfiner and Gilbert (1978). These latter two papers make use of kriging tech- niques. The kriging approach has definite advantages over previous methods. One of these is that estimates of precision are available on estimated Pu inventories for unit blocks of land. The reader is referred to these papers for details. We note that Dr. Delfiner is presently on a consulting contract with Battelle, Pacific Northwest Laboratories, to work on the application of kriging to environmental Pu studies. We have noted above that soil and vegetation Pu and Am data at new locations at safety-shot sites became available in 1977. These new data, in conjunction with the analysis of new unsieved soil samples from TTR and Area 11, total to over 500 new data points. We hope to analyze these data using kriging methods to estimate the spatial distribution and inventory of Pu at these sites if additional funding becomes available, To assist in the evaluation of kriging techniques for estimating spatial distribution and inventory, a special study was conducted along two transect lines at the Area 13 site during 1976-77 to investigate the spatial correlation structure of Am soil concentrations as well as FIDLER readings. Presumably, FIDLER readings and soil concentrations in 456