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July, August, and September. Precipitation amounts during this time in the drainage provided an excess of water that not only replaced or compensated for water that would have been normally consumed from reservoir releases but exceeded downstream usage demands. This resulted in reservoir water levels increasing, and necessitating water being released at unseasonably higher discharges from these facilities to prevent reservoirs from overfilling. Flow volume between 31 July through 9 October during 1999 was 96% higher than 1996, 15% higher than 1997, 100% higher than 1998, and 93% higher than 2000. On 4 October 1999, a mean daily discharge of 5,600 cfs was recorded at the USGS Whitewater gage which produced a peak flow that almost equalled the highest discharge of 6,100 cfs recorded on 25 May during runoff. During the 47-day period between 31 July and 15 September, daily discharge ranged from 1,210-2180 cfs in 1996, 2,090-3,280 cfs in 1997, 1,250-2,220 cfs in 1998, 2,430-4,510 cfs in 1999, and 1,500-2,160 cfs in 2000. There was some question and concern as to how, and if, the unseasonably high flows during this period in 1999 were associated with the reduced number of native fish, particularly Colorado pikeminnow, migrating through the passageway during the same period. Or, was the declining number of native fish migrating through the passageway in August, September, and October 1999 simply a normal seasonal pattern as that observed during the same period in the years when discharges were lower? The number of Colorado pikeminnow found in the fish trap declined from a high of 23 pikeminnow in 1998 to 5 in 1999 and 4 in 2000. Since there were insufficient numbers of Colorado pikeminnow to use for analyses, three of the more common native fish captured in the fish trap during all seasons and years were used: bluehead sucker, flannelmouth sucker, and roundtail chub. A biostatistician was consulted and he recommended several approaches that could be used to analyze and compare catches of these three native fishes with various discharges to determine if unseasonably high flows during this 2-1/2-month period in 1999 might have affected native fish migration through the fish passageway which resulted in decreased numbers of native fish captured in the fish trap. Ratio Method. Catches of the three native fishes most commonly caught in the fish trap during high-use months were compared with catches during low-use months and a ratio calculated (Appendix; Table I.1.). The higher the ratio, the fewer native fish collected during low-use periods. Ratios during years when post-runoff flows were seasonally "normal" could be compared with 1999. If the ratio was higher in 1999, this might lead one to suspect that the decreased catch of native fish numbers in the fish trap might be associated with the higher discharges during August, September, and October in 1999. 30