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Dolores River downstream from McPhee Reservoir to document movement of trout upstream and/or downstream with changes in flow regime within and between water years. More than 475 trout (including 289 brown, 157 rainbow, and 30 cutthroat) were tagged with VI tags between April 1 and October 4, 1991. During that time, 33 brown trout, 20 rainbow, and 5 cutthroat with VI tags were recaptured. One trout was recaptured during the fish trapping operation, five were recaptured by fly fishing, and 52 were captured during electro fishing operations. Fourteen VI tagged trout were captured three times during the study period. In all there were 72 instances where VI tagged trout were recaptured between May 13 and October 4, 1991. A very small percentage of the tagged recaptured trout had moved out of the original river segment (same mile of river) where they were tagged. Eighty-six percent of the recaptures occurred within the same river segment where tagging took place. Only 14% of the trout (5 brown, 4 rainbow, and 1 cutthroat trout) moved one river segment (0.7 miles) or more between the time of initial tagging and recapture. In 1991, there were seven instances of downstream movement and four instances of upstream movement. The farthest downstream movement was six river segments (from segment 1 to segment 7). The farthest upstream movement was four river segments (from segment 6 to river segment 2). Nine of the ten trout moving more than one river segment were initially tagged during the whole-river-boat- shocking operation between May 13 and 16, 1991, coincident with the beginning of the managed "spill" of McPhee Reservoir. It is quite probable that much (if not all) of the movement that occurred (both upstream and downstream) took place during the spill period. This conclusion is supported by the results of the fish trapping operations in July and August 1991 (Nehring 1992). The VI tagging and movement studies continued in 1992. Several hundred more trout were tagged during 1992. From the time of initial VI tagging in April 1991 through October 1992, there were 164 recaptures of VI tagged trout. Seventy-two percent were recaptured in the same section and 28% in a different section of river from where the tagging occurred. Of those recaptured in a different river section, 67% were caught in an adjacent river section and 33% had moved two or more river sections. Of the trout that had moved, 24% went upstream and 76% downstream. Results of the 1993 movement studies affirmed the findings of the previous years, when 54 VI tagged trout were recaptured that had been tagged in 1991 and 1992. Sixty-seven percent were recaptured in the same section where they had been tagged, while 33% were found in a different section. Of those trout recaptured in a different section, 72% were taken in an adjacent section and 28% had moved two or more river sections. Of the trout that had moved one or more sections, 67% went downstream and 33% moved upstream. It was interesting to note that as the peak and duration of the discharge into the Dolores River below McPhee Dam increased in 1992 and 1993, the percentage of VI tagged trout that moved into adjacent river sections increased each year as well. During 1991, when stream flows were maintained at 70 cfs or less (except for an 18 day managed spill ,that peaked at 843 cfs in May) only 14% of the VI tagged trout had moved one or more river segments from the point of tagging In 1992, the magnitude (2000 cfs) and duration (more than 30 days) of the spill was much greater than in 1991. By the end of 1992, 28% of tagged trout recaptures had moved one or more river segments from the point of tagging. In 1993, the managed spill lasted from March 1st through July 5th, or 126 days. The peak diSCharge exceeded 4100 cfs with several weeks of discharge ~ 2000 cfs. Electrofishing surveys at the end of the managed spill in 1993 revealed that 33% of the VI tagged trout were recaptured one or more river segments away from the point of initial tagging. In June and July 1993, electro fishing surveys from RM 13 to RM 32 at the Dove Creek Pump Plant resulted in the capture of 547 wild trout. Interestingly, not one VI tagged trout was captured in this 20 mile reach of river downstream from Bradfield Bridge, even though stream discharge exceeded 2000 cfs during the -15-