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contlucted periodically on foot through the winter ice-on season. Using an ATS receiver and 2.5 m whip antenna to monitor the individual radio frequencies employed, a given river reach was searched throughout a sampling day for all frequencies expected to be operational. Upon detection of a specific signal, an approach would be continued until the signal strength indicated the target fish was close enough to permit location through triangulation. Using the ATS receiver with a Smith Root directional antenna tuned to 30-32 MHz frequency range, the location of the signal would be pinpointed through triangulation from shore to determine the position and habitat type occupied by the fish. Afterward, the fish would be monitored for 15-30 minutes to determine its level of activity. Activity was classified as stationary, active within a specific habitat, or progressive movement upstream or downstream. During this observation time, the presence and location of adjacent habitat types, cover and aquatic vegetation would be noted. In some instances several radio-tagged Colorado squawfish and northern pike could be monitored in the same locality. Movements of these fish in relation to each other was also recorded if apparent. RESULTS YAMPA RIVER FLOW AND TEMPERATURE REGIME Comparison of flow regimes from 1988 through 1991 show differences in the magnitude of spring runoff at Craig and at Maybell, Colorado (Figure 3). Flow patterns were more similar for 1988 and 1991, and of greater magnitude than the flow patterns during 1989 and 1990. At both gage sites, sharp increases in flow occurred during early to mid-April in 1988-91, followed by a distinct dip in discharge of 1,000 to 2,000 cfs in late April to early May. This early spring peak was much smaller during 1990 and almost non-existent in 1991. These preliminary peaks were associated with warmer spring air temperatures that initiated rapid snowmelt in the lower elevation mountain valleys. Surface flow was observed in numerous wide-bottom gullies in the Maybell and Lily Park reaches. In 1988 this peak occurred about a week earlier than in 1989- 1991. Spring runoff increased to peaks of 6,500-7,500 cfs at Craig and 8,000-8,500 cfs at Maybell by mid-May in 1988 and 1991, and large-volume flows continued through mid-June in both years. In 1989, spring runoff peaked near 3,500 cfs at Craig and 4,000 cfs at Maybell by late April, fluctuated between 2,000 and 4,000 cfs through May,and declined steadily through June, approximately one month earlier than in 1988 and 1991. In 1990, spring runoff flows remained below 2,000 cfs through late May, increased to a peak flow from 5,000-5,500 cfs by mid-June, one month later and 2-3,000 cfs less than the spring peaks of 1988 and 1991. Flows then decreased below 2,000 cfs again by the end of June. Temperature records at gage sites were available only for the Maybell reach and these were incomplete in 1990. Concurrent with flow increases, water temperature in the river at Maybell increased sharply to 10 C after ice break-up and initiation of the preliminary spring 10