The Green River has been proposed as critical habitat for four endangered, endemic fishes. Colorado squawfish, razorback sucker, humpback chub, and bonytail chub. Two candidate species, flannelmouth sucker and roundtail chub, also occur. Much precipitation falls at higher elevations during winter months in the form of snow. Summers have afternoon thunderstorms that often result in debris flows from the side canyons.
Lower elevations are somewhat dry and hot in summer and cold and moist in winter.
Higher elevations are warm and wet during summer, and cold and wet during winter. Fall is generally dry and cool throughout the Section. The mean for July is a maximum 88 oF and minimum 58 oF. High elevation areas have approximately 40 frost free days, while lower elevations have about 120 frost free days. Surface Water Characteristics. Water is scarce over most of the area and is generally confined to steep canyons such as the Green and White Rivers.