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29 analysis, the average annual suspended sediment load from the Little Snake is 1,110,100 tons per year and the mean annual suspended sediment load for the combined rivers is only 1,517,300 tons per year. Compared to 1982, the 1983 field season at Mathers Hole incorporated improved data collection techniques, a greatly expanded sampling program, and collection of samples on both the rising and recessional limb. The '82 and '83 data are combined where appropriate in the analysis of sediment transport, but the 1983 data is generally used in obtaining sediment discharge versus water discharge regression relationships. These sediment regressions are presented in Table VI. The coefficient of determination (r ) is higher for the recessional limb than the rising limb and the correlation between the sediment load and water discharge is excellent (see Figures 13 through 18). The Mathers Hole and Deerlodge suspended sediment rating curves are nearly identical (Figure 14). Excellent correlation was found with USGS measured suspended load at Deerlodge Park and is shown in Table V and Figures 13 and 14. With these regressions and a flow-duration curve, and a load- duration analysis was performed on Mathers Hole data (Table V). The total suspended load using all the data from 1982 and 1983 is 1.91 million tons per year and alone, the 1983 suspended load is 2.13 millions tons per year. Applying the load-duration analysis to the historical gaging station data, the average suspended load is calculated to be 1.20 million tons/year, significantly less than the average annual measured suspended load at the gaging stations and that calculated from the Mathers Hole data. Andrews (1980) reported the average sediment yield for the Yampa Basin at 2.0 million tons per year. The load- duration analysis when applied with log regression relationships of sediment and water discharge will underpredict the annual sediment load. The best estimate of an average annual sediment load is 1.5-1.6 million tons/year from the gaging station records. Last year's sediment load represents a substantial higher sediment yield for the basin. The Helley-Smith sampler when combined with D-74 depth integrating suspended sampler is sampling, in theory, the entire flow zone of river. Only the sand sizes less than 0.25 mm which slip through Helley-Smith collection bag are missed in the sampling process. This sand fraction is referred to as the unmeasured sand load. The modified Einstein method for predicting total sediment load in the stream was applied to predict the unmeasured sand load. The results are presented in Tables V and VI. The unmeasured sand load was estimated to be 2% of the annual total load. Nine sets of data were collected at Mathers Hole in 1982 and forty- three sample sets in 1983. A statistical comparison was undertaken to determine if any substantial differences in the measured sediment data could be discerned. The data was divided into two categories involving the rising and recessional limbs of the hydrograph. The variables, total suspended concentration, suspended load, fine material load, and Helley-Smith load were tested. Assuming independent random samples of two normal populations with unknown means and variances, the t-test was used to accept or reject the hypothesis that there was no significant difference between the populations at the 5% significance level.