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I I I I I I I I I I I I I I I I I I I The consultant determined that raising the height of the dam at each of the nine reservoirs by five feet would add 3,1/;9 acre-feet of storage capacity. Raising the height of the dam at each of the nine reservoirs by ten feet would add 6,/;22 acre- feet of storage capacity. The moderate amount of additional storage which could be obtained by raising the height of the nine dams, even if there were no major obstacles to such work, shows that this is not a promising approach. There are, however, numerous obstacles to raising the height of these dams. First, it has in past studies been determined that geological conditions on Grand Mesa would effectively impede construction of larger dams than those which already exist. A review of topographical maps of the Grand Mesa area did not reveal any previously undeveloped morraines that could serve as additional storage reservoirs. Second, suitable fill material for larger earth dams would be difficult to obtain within reasonable hauling distance. Third, the headwaters dams are on land owned and managed by the U.S. Forest Service and construction work to rehabilitate or enlarge any of the dams would require prior approval by that agency. Such approval would be granted only after compliance with lengthy and costly procedures including preparation of environ- mental impact statements. Fourth, access to most of the dams is difficult. Based on the foregoing problems, it is evident that adding storage capacity at existing headwaters reservoirs is not an attractive option and may, in fact, be a non-viable option because of physical and institutional constraints. C. Alternative Storage Sites The preceding paragraphs indicate that average annual water shortages cannot be alleviated by (I) non-structural measures such as a reduction in diversions or changes in the point of use for releases from existing reservoirs nor by (2) enlarging the storage capacity of the existing headwater reservoirs because of physical and institutional obstacles. Thus, it appears that construction of new storage is the most promising option. This conclusion was reached in nearly all previous studies, including the investigation concluded in 1985 by the consulting firm of Western Engineers. IV-8