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supply to the Deerlodge Park reach and to the Yampa Canyon. This combined suspended sediment supply was compared to the predicted suspended sediment load that could be transported (capacity) at Mathers Hole using the revised regression relationships appl led to the daily discharges for the entire period of record (64 years). All the sediment discharge calculations were made employ I ng the revised regression relationships in Table 3. The summation of the upstream daily water discharges was assumed to equal the dai I y discharge at Mathers Hole for that day. The predicted difference between the upstream sediment supply and the sediment transport capacity in the canyon results in a surplus (+), storage or deposition of sediment from the canyon or scour (-), the removal of sediment in the canyon. It may be more appropriate to state that a negative value indicates a potential to scour. There are several important assumptions inherent In this analysis: 1. The sediment regression relationship (Table 3) used as a predictor for the measured load Is only a function of discharge. 2 . The regression relationships used In this study w i I I reflect only long term trends and not the short periods of severe overloading. The actual measured load ( e s p e c i a l l y for the Little Snake) w i l l greatly fluctuate diurnally and will display different regression relationships for the rising and fal I ing I imbs as shown in 0' Br i en' s (1984) report. 3. There is some lag time between the arrival of the annual peak water discharge and peak sediment load at Mathers Hole. The daily loads are additive and, therefore, this impact of lag time should be negated in the long term analysis. 4. The actual storage and/or scour of sediment in the canyon is subject to localized physical conditions and processes. Sediment often tends to move in waves. Sediment transport, deposition or scour Is a function of numerous variables including slope and sediment size distribution. Sediment transport Is a selective process according to size fraction and localized armoring of the bed may inhibit further transport of the finer sediment sizes. These variables may cause sediment storage In a pool during a time when the canyon Is experiencing general scour. Sometimes sediment being stored may Itself induce the local processes to increase or decrease the sediment transport thereby changing the regression rel ati onsh i ps. The results should only be interpreted as indicating a general or long term trend and not necessarily the exact local conditions that would have occurred in the canyon based on the computational criteria. 5. The concept of scour (negative storage) in the canyon is a vague one because once the fine sediment is removed from the bed and the bed Is armored, no further sediment can be removed. These values should indicate only a potential to scour. 11