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<br />1 <br /> <br />. <br /> <br />.. <br /> <br />COMPARISON OF RECENT HYDRO GRAPHS <br />Snowmelt-generated flows in the upper Colorado River were much higher in 1995 than <br />1994, and slightly higher than 1993, the most recent year of high flow (Figs. 2 and 3). Snowmelt <br />hydrographs for the Colorado River near Cameo (USGS station 9095500) and the Colorado River <br />near the Colorado-Utah State line (USGS station 9163500) generally mimic each other, with some <br />differences due to variations in flow from the Gunnison River. Compared to 1993 and 1994, the <br />peak of snowmelt in 1995 was delayed by several weeks, the peak was relatively high, and high <br />flows persisted long into July, about I month longer than usual (Figs. 2 and 3). Provisional flow <br />data for 1995 supplied by the USGS indicate that the Colorado River reached peak discharges of <br />29,600 cfs at Cameo and 49,300 cfs at the State line. The peak discharge at Cameo ranks as the <br />7th highest in 61 yr of record and the peak discharge at the State line ranks as the 5th highest in 45 <br />yr of record. Equally significant was the fact that high flows persisted for some time- at the State <br />line gauge, the mean annual flood of 27,900 cfs was exceed for 45 days. Annual runoff at the <br />Cameo and State line gauges totaled 3,852,000 and 7,079,000 acre-ft, respectively. The 1995 <br />peak discharges and runoff volumes were the highest since 1984. <br /> <br />METHODS <br /> <br />The 3 backwater study sites and the main channel cross sections were re-surveyed in late <br />August 1995. Cross sections at the backwater sites are monumented by 'rebar' endpoints. These <br />cross sections were surveyed with a level and fiberglass leveling rod or an electronic total station. <br />The main channel cross sections were not in all cases monumented with rebar; this led to some <br />problems of relocating the exact endpoints of a few cross sections, particularly those established 2 <br />years ago, but we were able to re-Iocate most endpoints. All of the main channel cross sections <br />were surveyed using an electronic total station and a motorized rubber raft outfitted with a depth <br />sounder. In this method, the total station was set up over one of the cross section endpoints, <br />distance readings were taken along the section line by targeting a prism on the rubber raft, and <br />depth soundings were taken by the person on the raft and relayed by radio to the person on shore. <br /> <br />4 <br />