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6 I I I I I I I I I I I I I I I I I I I poor and needs to be plugged. The outlet was rated as "acceptable". 6. Soillwav. This 'appears too small' and had inadequate freeboard. There was concern the dam could be overtopped by wave action. The spillway was rated "poor". In summary, the major problems the state Engineer has with Rapid Creek ~l are the outlet works and the scarp formed on the upstream reservoir. He recommended that a $tudy be done to evaluate seepage and slope stability, On Rapid Creek #2, the main concerns were with inadequate freeboard and not properly abandoning the right outlet pipe. Again, they recommended a $tudy to determine the extend of seepage and slope stability. They also recommended an interior inspection of the Rapid Creek #2 outlet. D, DESCRIPTION OF DRAINAGE AREA. Grand Mesa, the land fo~m on which the Rapid Creek reservoirs are located, is a large basalt capped plateau that forms one of the most promin~nt physiographic features in west-central Colorado. It i~ drained on the north by Plateau Creek and on the south by th~ Gunnison River. Its top rises approximately 4,000 to 5,000 feet above the adjoining river valleys. Its basalt cap, which is 300 to 400 feet thick, was deposited by ancient lava flows which originated in the east part of Grand Mesa. The topography in the e~stern part of Grand Mesa is rugged and varied, consisting of a series of benches, escarpments, ridges and drainage systems and is covered with thick spruce and fir forests. The topography on the west end is generally flat to gently ~olling, with low, rounded ridges and shallow, wide valleys. The vegetation consists of grass and sagebrush, with occasion~l patches of fir and spruce. At its far west end, Grand Mesa splits into two arms, which are separated by the deep valley of Kannah Creek. The north arm, in which the Rapid Creek reservoirs are located, is known as Lands End. The total drainage area of Rapid Creek above the two reservoirs is 1.77 square miles. Of this, 1.23 square miles is above Rapid Creek #2 and 0.52 square miles drain directly into Rapid Creek #1. Slopes range from 1% to 3%. Almost all of the vegetation in the drainage area is grass and sagebrush. The soils are very rocky, and consist of glacial deposits and outwash from the glacial deposits. All of the rocks within the soil are of basalt origin.