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in the size ranges of: sand and gravel, silt and clay, 0.062 to 0.25 mm, and 0.25 to 1.0 mm; therefore, one sediment-transport equation for each of these sediment categories was sufficient for subsequent analyses. The relations were significantly different for bedload discharge and for the discharge of sediment coarser than 1.0 mm. However, bedload and the discharge of sediment coarser than 1.0 mm were not highly correlated with streamflow; therefore, determi ni ng separate sediment-di scharge equations for ri si ng and recessi ona 1 periods was not reasonable for these two sediment categories. . Occasionally it may be necessary to estimate the total sediment discharge of a river--for example, when reliable bedload discharge measurements are unavailable. Several computational techniques have been developed to estimate sediment discharge for different sizes of bed material. Total sediment discharge at Deerlodge Park was estimated using the Modified Einstein proce- dure, and these estimated sediment discharges were compared to measured sediment discharges. The Modified Einstein procedure computes total sediment discharge at a cross section for a river primarily having a sand bed. This procedure uses measured hydraulic variables, the mean concentration and particle-size distribution of measured suspended 'sediment, and the size distribution of material in the bed. The procedure consists of computing the sediment discharge for several ranges of particle sizes by applying different methods of computation for the small particle sizes than for the large parti- cle sizes (Colby and Hembree, 1955). Estimated sediment loads for Deerlodge Park were calculated with the Modified Einstein procedure using a computer program written by Stevens (1978). Calculated total sediment discharges, and sediment discharges in various size categories are presented in table 14 in the Supplemental Data section at the end of this report. Sediment discharges estimated by the Modified Einstein procedure were greater than measured sediment discharges for virtually all observations in every sediment size class. Differences in sediment' discharges were largest in the coarse sand- size . ranges. Some of the estimated sediment discharges in the 0.5-mm to 1. O-mm, and 1-mm to 2-mm size ranges were much greater than the measured sediment discharges; whereas, in the 4-mm and larger range the estimated sediment discharges were less than the measured sediment discharges. Di sparity between measured sediment di scharges and estimated sediment discharges could be a result of undersampling by the Helley-Smith sampler or from overestimation by the Modified Einstein procedure. Measured sediment discharge could be understated because material finer than 0.25 mm (the mesh size of the Helley-Smith sampler) is not totally accounted for in the area of flow sampled by the Helley-Smith sampler. Also,: the correction factor applied in suspended sediment computations for the percentage of streamflow actually sampled may be too great if dune bedforms are present (D. W. Hubbell, U.S. Geological Survey, oral commun., 1984). Measured bedload transport rates are subject to error from several sources. Although all bedload samples at Deerlodge Park were co 11 ected at the same i nterva 1 s and on the same cross section, the exact location of the bedload sampler with respect to bedforms "J:'lS never known. Logistical considerations limited the duration of bedload sampling, and as such, temporal variations in bedload discharge could not be entirely accounted for. Another source of disparity in bedload measurements could be in the hydraulic efficiency of the sampler- design (Hubbell, 1964). The ratio of sampler nozzle entrance size to exit size affects the hydraulic 17