Red Fleet Dam and Reservoir are constructed on Big Brush Creek about 3.5 miles downstream from the crossing of State Highway 44 and about 10 miles northeast of Vernal, Utah. The dam is zoned earthfill with a structural height of 144 feet above the bed of Big Brush Creek. The crest length is 1,670 feet long and 30 feet wide. Red Fleet Reservoir has a total capacity of 26,000 acre-feet, of which 24,000 acre-feet is active storage. The reservoir has a surface area of 521 acres at the normal water surface elevation of 5,608.2 feet.
Red Fleet Dam and Reservoir are located on the south flank of the Uinta Mountains in the unglaciated valley of Big Brush Creek, a tributary of the Green River. The stream begins near the crest of the range and flows in a southwest direction to the Green River. The oldest rocks exposed in the drainage area are Precambrian age and occur in the headwaters of the basin. Successively younger rocks crop out down the river valley. These rocks form a thick layer of roughly parallel sedimentary beds as young as mid-Cretaceous in age. Initially, they formed a horizontal layer overlying a relatively flat erosion surface on Precambrian age. Following the uplift in late Cretaceous time, they formed an anticline over a core of Precambrian rock. Erosion removed the cover over the crest of the fold and the Paleozoic and Mesozoic rocks now occur on the flanks of the range as a succession of outward dipping beds. Rock formations of Mesozoic age underlie the reservoir, while the damsite is underlain only by rocks of Cretaceous age. Further downstream, Tertiary age sediments, deposited after the older beds were folded, blanket the Unita Basin floor and cover many of the interstream areas on the mountain slope. These rocks occur in relatively horizontal layers and in many places lap up on the eroded edges of the older sediments.