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66 I I I I I I I I I I I I I I I I I I I The common native fish scenario may have a negative im- pact on humpback chub in June, when chub larvae are still dependent on rearing habitat in the Little Colorado River. Low flows during this period would allow the Little Colorado River to flow freely into the Colorado River and transport larval chubs into the mainstem river, an inhospitable environment for them. By July, larval chub have grown to a size where they can survive in the mainstem and low flows no longer af- fect th~m. steady flows in winter would benefit trout by eliminating the low water that accompanies winter fluctuations and exposes spawning areas. However, absence of fluctuations would decrease food availability. Low flows in the summer have no effect on trout because they are not spawning. Beaches, terrestrial vegetation, and most wildlife would benefit from this nearly steady-state scenario compared to current operations (Appendix A, section II). Veg- etation would benefit from the lack of floods and ex- pand in area down to the level of the 26,000 cfs peak flow. However, low flows in summer may cause moisture stress to young plants. White-water boating would be seriously impacted under this scenario. Low flows during the peak rafting months of June, July, and August would severely reduce the recreational value of white-water boating and in- crease hazardous conditions in the rapids. The negative impact to white-water recreation during these three months generally outweighs the potential benefits to rafting during the remainder of the year. When compared to current operations, an average of $1.5 million in white-water recreation benefits would be lost annually through releases for common native fish. (See Appendix III, Chapter IV.) Releases For TROUT Balance conflicting Requirements For Reproduction And Growth The seasonal needs of rainbow trout reproduction and growth within the Glen Canyon fishery suggest that both fluctuating and steady flows may be beneficial at specific times of the year (Figure VII-3). Steady flows from December through March to provide minimum