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7 . Even small depletions of water from the Gtmnison River may be detrimental to the survival 'and reproduction of the Colorado squawfish and humpback chub. ,Recent biological information indicates that high spring runoff may affect reproductive activity in the squawfish and humpback chub. Therefore, impoundments that reduce or alter high-water levels may reduce reproductive success of the endangered fishes. In addition, reduced flows prevent overbank flooding which replenishes essential nutrients and provides essential backwaters where juvenile and young-of- the-year fishes may seek food,and shelter. Depletion of water from the Gunnison River as a result of the CRSP reservoirs would eliminate peak flows that create eddying and backwater habitat essential to squawfish and humpback chubs. Because populations of both species occur in the Colorado River immediately downstream from the confluence with the Gunnison, it is important to not reduce present flows unless we obtain good bi.olog:l.ca1. data that suggests such reductions would not be harmful: In addition to reduced water flow problems, other water conditions ass'oeiated with returning irrigation water are increases i~ salinity and changes in water temperatures. Although these water quality conditions are important and may limit spawning or possibly distribution of species, it is our opinion that increases in salinity that would result from the Dallas Creek Project are 'not as limiting to the squawfish and humpback chub as the actual loss of water itself. Colorado squawfish and humpback chubs are found in the Colorado and Green Rivers where salinity ranges from 200-1700 mg/l. Increases in total disolved solids (IDS) from Dallas Creek are estimated to be 10.4 mg/l at Grand Junction to 2.7 mg/l at Imperial Dam. These increases would not significently change total IDS levels in the Gunnison or Colorado Rivers. We concur with the statement in the biological assessment that downstream water temperatures would not be adversely affected. The warming effect of the extensive use and reuse of the water for irrigation in the Uncompahgre Valley would ,offset releases of cold water from the Dallas Creek Project. We also agree with the biological assessment that water quality conditions may improve in the Uncompahgre River as ,a result of the project. Heavy metals and other toxic materials would settle out in the reservoir. However, water quality should be monitored within the reservoir as well .as in the river upstream and downstream of the reservoir. We understand the Water and Power Resources Service (WPRS) is working with the Environmental Protection Agency in planning for this endeavor. The cumulative effects from the above projects constitute a serious threat to the existence of the Colorado squawfish and the humpback chub. Therefore, it is our biological opinion that the Dallas Creek Project, along with ,the cumulative impact from related Colorado River Storage Proj ects currently in operation and others expected to be completed during the life of the Unit, is likely to jeopardize the continued existence of tbe Colorado squawfish and the humpback chub.