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<br />'. .. <br /> <br />,., <br /> <br />OOH68 <br /> <br />The comparison of findings of this evaluation to those made in the earlfer <br />USBR study will be discussed in subsequent sections of this report. <br /> <br />3.3 Winter of 1984-85 Observations <br /> <br />3.3.1 Observation Program <br />Although there were previous investigations of the Gunnison River icing <br />problems made by the Bureau of Reclamation, there are only a few years where <br />field records were maintained to define the actual movement of the ice jams. <br />A vital component of this investigation was therefore to obtain an accurate <br />record of the ice formation, movement and resulting flooding during the <br />1984-85 winter season. In addition, these field observations are extremely <br />helpful in gaining a more detailed understanding of the specific site <br />conditions relating to the mechanics of the ice jam formation and flooding <br />caused by the jams. <br /> <br />While the leading edge or head of the ice jam can be tracked down by observers <br />on foot, it was decided to supplement the on-ground data collection with <br />regular interval aerial observations. This allowed photographic recording of <br />both the ice jam location and the path of out-of-bank river flows. <br /> <br />It was necessary that the observers be local residents, famfl iar with access <br />to the river, who could respond to rapid changes in temperature conditions and <br />who have a good knowledge of the icing mechanics. Dr. Bruce Bartleson of <br />Western State College and two of his students were employed by MKE to provide <br />the primary field observation records. Dr. Bartleson has previously studied <br />the Gunnison River icing problem and was involved in obtaining data for the <br />1979 USBR report. <br /> <br />The written descriptions provided by the Gunnison observers are included in <br />the appendix along with many photographs which illustrate the progression and <br />recession of the jam over the 1984-85 Winter Season. Only a limited number of <br />the appendices have been produced. The map on Figure 1 shows the study area. <br />Note Taylor Park Reservoir upstream of Gunnison and Blue Mesa Reservoir <br />downstream. Tomichi Creek is one of the ma in tributaries to the Gunnison <br /> <br />-13- <br />