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(3 293 000 tonnes per year for 1975-86) satisfies the difference computed for the bed-material load estimates for sites B and C. Table 5. - Summary of mean annual sand load of the Green River and major tributary streams. Mainstem Mean annual Mean annual site Tributary Period Q, m3/s %, tonnes/y A 1965-87 129.9 1 343 000 B 1965-87 129.9 1343 000 Duchesne 1965-87 18.1 42 000 white 1975-86 23.9 925 000 C 1965-87 183.4 2 640 000 Price 1965-87 4.5 Gauge 09315000 1965-87 181.5 2 803 000 Note: Sand load data is not available for the Price River. At gauge 09315000, the mean annual bed-material load was about 6 percent larger than the load computed for site C. The main tributary in the intervening reach, the Price River, is gauged about 56 kilometers upstream of its confluence with the Green River. Inadequate gauge records prevented the calculation of average annual sand load from the Price River. The mean annual discharge of the Price River is about 2 percent of the flow of the Green and is not likely a major contributor to the total sand load of the Green River. On average for 1965-1987, the bed-material load of the Green River at gauge 09261000 was nearly 50 percent of the river's bed-material load at gauge 09315000. Suspended sand load in the White and Duchesne Rivers account for about two-thirds of this difference, 967 000 tonnes per year. Assuming a 10-percent bedload correction factor for the White River satisfied the difference. The mass balance of bed-material loads, calculated from the long-term gauge histories of the Green River at intermediate sampling locations, indicated that the Green River was transporting just the sand load that was delivered to it throughout, this reach during 1965-1987. Discharge Patterns Andrews (1986) reported no changes in mean annual flow at the two mainstem Green River gauges 09261000 and 09315000 following closure of Flaming Gorge. However, he found changes in the duration of flow pattern of the Green River, reporting that the magnitude of flows that occur less than 10 percent of the time decreased significantly after regulation. Figure 4 contains the annual peak flows for gauge 09261000 for the period covered by the aerial photography for study reach 1. The peak recorded in 1984, 1133 cubic meters per second, is the largest reported for the entire gauge history. These data were separated into three periods, 1953-64, 1965-78, and 1979-86, corresponding to the photographic intervals. An analysis of covariance showed no statistically significant difference (a = 0.05) in the means of the annual peak flows for these intervals. A similar analysis of the annual peak flow data for gauge 09315000 (fig. 5) indicated no statistically significant differences in the means of these data The peak flows at this gauge were separated into three periods: 1953-74, 1975-81, and 1982-87, based upon the dates of aerial photography for reach 2. 10