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placed in the channel of Scullion fulrh and ;+s rr;hurarie~ to act as sediment control measures while the D-Portal area is being reclaimed. The dams have a combined storage capacity of 1_.74 acre feet, which is adeciuate for the .51 acre feet of_sedimeni`,~hla~_,w.i. umulate over a_three year period. Each dam is three toYfive feet high with side slopes of 1.5h:1v. An overflow spillway, consisting of a trapezoidal channel with a four foot bottom width, 1.5h:1v side slopes and a one foot depth, will be constructed in the dam. Additionally, sediment control measures will be implemented in the D-Portal Area to mitigate the effects of erosion on surface water flow in Scullion Gulch. These include contour furrowing and anchored jute netting to retain mulch on slopes of 3h:ly or greater. The D-Portal Area comprises only 0.6 percent of the entire Scullion Gulch drainage basin. The 7.74 square miles above the D-Portal area will contribute 6.02 acre feet of sediment over a three year period 'as compared with the .51 acre feet expected for the D-Portal Area itself. The applicant has not speci- fied the longevity or maintenance of these dams. Obviously, the available storage is not sufficient to contain all the sediment from the upstream drain- age area, and the dams will theoretically fill with sediment within a year. Although this is a good faith effort to provide sediment control, the size of the problem does not warrant the construction of thirteen rocks check dams. To provide sediment control in this manner will certainly cause the channel to de- stabilize at some time unless the dams are cleaned out frequently. Further- more, the amount of sediment involved is negligible, the reclaimed D-Portal would contribute only 9.3 percent of the sediment load to Scullion Gulch if the check dams were not installed (page V-22a of the permit application). T~e- fore it is recommended that the applicant omit from *na n_anrr ~l rnr lama };nn plan all the rock check dams in the main channel and tributaries of Scullion ~y]Sh with the exception of three dams or sediment traps, built to SCS or U.S. Forest Service specifications, to be installed at the downstream limit of the D-Portal Area. These s uTa provide sufficient storage to store one year of sediment accumulation from the D-Portal area. The traps will be constructed prior to the onset of reclamation, cleaned periodically throughout the reclama- tion period until the appropriate regulatory authority has deemed reclamation complete, at which time the controls will be removed. (See "Stipulations" in this section of the TEA). 17