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0" ~ :' r.; .1 .J ,u. years when Blue Mesa is expected to fill (normally about 85 percent of the time). To facilitate diversion of the river during construction, the contractor will be permitted to reduce flow in the river to 10 second-feet for one 48-hour period during the months of December through February. Concern has been expressed with possible abrupt changes in releases from Crystal Dam. Such changes can be dangerous to downstream recreation-users in the summer. Operating criteria will be prepared to regulate such surges. During construction abrupt changes in flow will be controlled by restricting the contractor to a change rate not to exceed 100 c.f.s. per hour whenever flows are less than l,200 c. f. s. Similar procedures will be investigated for actual operations. The construction contract will include many restrictive clauses concerning water and air pollution, contractors' operations, specifying location for waste generated in the project opera- tion, treatment of waste water, disposal of petroleum products, etc. It is planned to restrict the contractor's operations in the river channel to the periods of low flow after the spring runoff in June until September. The river's sediment carrying capacity will be less during this time. It may be necessary to forego power revenues from Morrow Point and Blue Mesa in order to hold back high flows during that time. The attached paragraphs, taken from the diversion tunnel speci- fications, are submitted to indicate the type of restrictive wording to be included in the environmental quality protection section of the construction contract. Water quality require- ments specified in the paragraphs are related to aggregate production, channelizing, or any potential activity in which the contractor engages that may disturb existing water quality. Only commercial aggregate operations that comply with State and Federal pollution regulations will be designated as approved sources for contractors supplying aggregate to the Crystal Dam construction operations. All five of the commercial sources designated in the diversion tunnel specifications are existing operating pits or were opened at one time and are now inactive. The source owned by the Bureau of Land Management is also an operating pit. The use permit for this source specifies that top soil be stockpiled and replaced over excavated areas, ade- quate drainage be provided, and the final area graded and seeded to restore a natural appearance. . Disposal of waste material in the reservoir will be in desig- nated areas located 25 feet below the minimum operation level of the reservoir and above the river channel. Fill slopes 10