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2 METHODS AND ~~TERIALS Selection of Study Streams Following consultation with DOW personnel and consideration of the availability of U.S, Geological Survey flow records a preliminary list of 30 Class I (critical) or Class II (high priority) streams was compiled. After consultation with personnel of the IFSG and further consideration, this list was reduced to 15 streams (Table 1). Carnero Creek, a Class III stream (U.S. Environmental Protection Agency, U.S. Fish and Wildlife Service, and Colorado Division of Wildlife, 1979) was included because DOW personnel discovered it contained an endemic population of Rio Grande cutthroat trout (Salmo clarki viginalis) and thus should be rated as Class I, not Class III. One or two reaches of each stream were selected for survey ac- cording to selection criteria and techniques outlined by Bovee and Milhous (1978). Placement of the lower and upper cross sections was governed by the presence of a flow control point or a critical riffle. A flow control point is defined as a restriction or an obstruction in the stream channel aCross which the stream energy gradient reaches ftn inflection point (Bovee and Milhous, ibid.~, Field Data Collection Plan An intensive evaluation of the annual discharge patterns of study streams was made using the Water Resources Data for Colorado (U.S. Geological Survey, 1961-1978). Using these data and estimat- ing the anticipated maximum run-off time and volume based on the snow-pack data available for the various study areas, a prospective field schedule for 1978 was set up to maximize efficiency by mini- mizing travel time. In most instances, a field trip consisted of 3 to 5 days, and three to five study sites were evaluated each time. This worked out very well, since out of 168 man-days spent in the field over the 7 month field season, only 3 man-days were lost due to misjudgment of anticipated stream discharge. Every attempt was made to survey the study streams at levels near maximum run-off, median annual discharge, and minimum annual flow. However, on the larger study streams, the upper level of flow evaluation was set at a level double or triple the amount of water that would probably be recommended as an instream flow request. In only two instances were we unable to meet the objectives of our plan for collection of field data. One was on the East River where the lower four crOSs sections were inundated by water backed up aCross the lower flow control point when DOW personnel set up a low diversion dam across the flow control point to divert a spawn- ing run to kokanee salmon out of the East River into an irrigation canal for trapping and spawning operations. As a result, only the upper two cross sections were resurveyed and only twice instead of three times. The other problem occurred on the South Platte survey areas when the Denver Water Board refused to allow DOW personnel in to do cross section work without a court order. On the other 13 streams, the objectives of the field data collection program were realized (Table 2).