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6 Physical Habitat The average spring peak flow is 36,155 cfs for the period of record (1914-1996) which encompasses both pre- and post-regulation periods for the Colorado River, near Cisco. The historic peak (pre-regulation) was 73,200 cfs (tJSGS gage),~and the highest post-regulation peak (after 1961) was 69,500 cfs, in 1984. Interestingly, the 3"' and 4`~ highest peaks occurred during this study, in 1993 and 1995. Based on the average peak, this study encompassed 21ow water years (<50% of avg.), 2 high water years (>130% of avg.) and one moderate year (80% of avg.). Physical habitat variables of interest, and catch of Colorado squawfish and NNCs were summarized for each sampling occasion. The data are grouped by year and season in Tables 2 and 3. The relationships between peak flow, sampling flows, and habitat quantity were tested using Peazson's correlations (Table 4). On all occasions, there was a negative correlation between higher sampling flows and habitat availability, although the results were only significant to the O.151evel at best. More significant negative correlations were seen between peak flows and habitat quantity in the summer in the upper section, and between peak and fall habitat in the lower section. Rakowski and Schmidt (1996) studied asand-bedded reach of the Green River similar to the Colorado River reaches. They suggested that habitat quantity may decrease in the year of a high peak flow, but that the following year or years may benefit as lower floods in succeeding years scour bars created during a high flow yeaz, thereby increasing habitat complexity and quantity. Therefore, the relationship between peak flow offset by 1 and 2 years and the fall habitat availability was also tested. There was no correlation between a 1-year previous peak flow and habitat. A slight negative correlation observed on the 2-year offset was an artifact of the similarity between the patterns of peak flows offset by two years, 1990-1994 and 1992-1996.