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Show the channel was constructed with the natural streambank on one side and the newly formed bar on the other. Since resistance to the erosive force of the water was nearly equal for both the streambank and bar, portions of both were removed. The total effect was the deteriorated channel condition which is observed today. " B. Project Impacted Streams " 1 Sixth Water " Sixth Water Creek was the natural channel selected to convey Strawberry irrigation water. For the last 60 years the drainage has contained flows more than 30 times its natural capacity, and the results have been devastating. " Sixth Water Creek is a deteriorated stream channel. Its narrow winding course has been replaced by a gouge averaging 36 feet in width. " The once stable grass- covered banks are now raw, unstable, and exposed,, The gravel beds have been removed, and silt and boulders now occupy the streambottom. A land flow a quarter of a mile wide has been activated as a result of the widening and downcutting of the channel. Sixth Water is a vivid example of the effects of water transport via natural channel conveyance when no attempt is made to align artificial flows with natural capacities. " By constructing the Diamond Fork complex of the Central Utah Project, the problem of excess flow will, be eliminated. New problems, however, will arise. The stream channel is so large and the bottom material so coarse that the natural flow will take several years to entrench itself in a small, well- defined channel. " Sediment which enters the stream system is likely to increase as a result of construction activities further deteriorating the aquatic habitat. Since spring peaks will be eliminated, the fine sediments can be expected to persist and may eventually choke 257 |
