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ooln98 . . major tributaries, including the Yampa River. There has not been a recorded capture of a Bony tail chub in the Yampa River in recent years. A remnant population may exist in Dinosaur Canyon as indicated by infrequent collection of individual fishes. The stated recovery goal of the Recovery Program is to "prevent immediate extinction." All of the proposed critical habitat reaches for the bony tail chub are located downstream of the Elkhead Project. These include the Yampa River below the boundary of Dinosaur National Monument, the Green River from the confluence with the Yampa River to the boundary of Dinosaur National Monument, the Green River from Summer's Amphitheater to Fish Ford, the Colorado River from Black Rocks to Imperial Canyon, and two additional . downstream reaches in the Colorado River in Utah and Arizona. ON-SITE IMPACTS OF PROJECT CONSTRUCTION Reservoir Inundation Area The surface area of the existing Elkhead Reservoir is approximately 550 acres. If Elkhead Dam were raised to elevation 6,420 MSL, the new reservoir surface area would be roughly 1,068 acres, representing an additional maximum inundated area of 518 acres. The actual amount of lands inundated would vary seasonally and on an annual basis depending on hydrologic conditions and reservoir operations. During low runoff years and during months of high reservoir storage use, e.g. later summer and early fall, the enlarged Elkhead Reservoir would be drawn down to lower levels leaving exposed,unvegetated areas. Under current conditions, exposed banks within the reservoir basin occur infrequently due to only minimal use of reservoir storage. This situation is likely to change, even without reservoir enlargement, as future increases in water demands require more storage releases. Based on results of modeling studies of the enlarged Elkhead Reservoir (discussed below), the average seasonally exposed areas would be as follows. Month Average Exposed Acreage October November December January February March April May June July August September 149 151 152 152 153 146 34 '8 17 70 123 146 11 ,'..,""