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~ Thus, the canal could divert only 87.8 ft3/s. been charged against reservoir releases to the that time. This l2-percent loss has Colorado Canal since (,e The problem of transportation loss to the Colorado Canal was again studied by Lacey (1941), During the course of his investigations, ev- ery reasonable control over the river and the diversions was exercised. After studying in elaborate detail each of the seven reservoir releases made in 1939-40, Lacey concludes: "In my opinion, exact determinations as to loss in transit to the reservoir head in progression are impossible because of the many influencing factors encountered which are beyond con- trol. There are too many variables present in the situation, which tend to obscure the graphic record and make objective conclusions difficult." In the final analysis, Lacey could not justify changing the l2-percent loss rate, Lacey (1941) also noted travel time during his studies, but because the seven reservoir releases were all made during periods with similar antecedent river conditions, the results indicated similar travel times, As a result, these determinations were not valid for different anteced- ent flow conditions. I' Recently, Wright Water Engineers (1970) did a preliminary study of travel time and transit losses along the Arkansas River. Three categor- ies of losses were studied: evaporation, bank storage, and "unauthorized diversions." The magnitude of these losses varied with the amount of the release and the natural river flow at Canon City. For typical res- ervoir releases, the losses as defined from their report are somewhat less than the l2-percent rate. Time of travel is also given in the report for releases from Twin Lakes, Turquoise Lake, and Clear Creek Reservoirs to several locations downstream, including the Colorado Canal headgate. The flow at Canon City and the amount of the reservoir re- lease were used in determining travel time. .' HydroloRic SettinR of the Upper Arkansas River The upper Arkansas River is that portion of the Arkansas River that extends from the Continental Divide north of Leadville (elevation, 10,200 feet) downstream to the vicinity of Pueblo (elevation, 4,670 feet), a distance of about 170 river miles (fig. 1). Above Canon City, the river typically consists of pools and rapids. Although the river primarily flows through hardrock canyons in this reach, it also trav- erses a total of about 37 miles of alluvial deposits north of Salida, near Buena Vista, and south of Leadville. Land in these areas is widely used to grow hay, with flood-type irrigation commonly practiced. Below 4 .