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h <br /> e <br />streams to satisfy these rights. Consequently, the expansion of t <br /> quarry should not injure any direct flow water rights on Turkey Creek or <br />' Bear Creek. <br /> There are various storage rights on Bear Creek and the South Platte <br /> River downstream from the Morrison Ouarry which could be affected by the <br />' expanded gravel mining operations. Also, the Town of Morrison recently <br /> filed for a reservoir on Strain Gulch. The gulches tributary to the <br /> mining area are no[ continuously flowing; water is available only during <br />t the snowmelt runoff season and after storm events. Most storage rights <br /> depend on water captured during these periods, so there is a greater <br /> potential for injury to these rights by the mining operation than direct <br />' flow rights. <br /> Under the criteria for drainage control outlined under Alternatives I <br /> and II in this report, most runoff water will be carried around the pit <br />' area and into the natural channel downstream in the historic manner. <br /> Consequently, potential impacts on downstream water rights are minimized <br /> under these options. Although it is unlikely that any water would be <br />' permanently detained in the quarry under Alternative III, [he return of <br /> runoff water to the stream system would be delayed under this plan. <br /> This lag effect and evaporation losses may adversely affect downstream <br />' water users. <br />' SUMMARY <br /> This report describes the hydrologic features and characteristics which <br /> may be affected by a proposed expansion of the Cooley Gravel Company's <br /> Morrison Ouarry, the extent to which the expansion may have an impact on <br /> these features, and measures which may be taken to mitigate any adverse <br /> impacts. <br />1 <br /> The drainage system required to protect the operating areas and to <br /> minimize damage potential downstream is comprised of two parts, an <br /> external and an internal drainage network. Under two of the alter- <br />' natives presented, the primary component of the external drainage <br /> network is an open channel to intercept runoff from the undisturbed area <br />' above [he quarry pit and convey it around the pit and into the natural <br />channel below. Under the third alternative, runoff is allowed to flow <br /> into the quarry in a controlled manner. <br />' All runoff not coveyed around [he mining area, including surplus runoff <br /> over the capacity of the diversion channel under Alternatives I and II <br /> and all runoff from above the quarry under Alternative III, will enter <br />' the pit area. There, it will be controlled by the quarry's internal <br /> drainage system. The internal drainage network includes drainages <br /> ditches, drop structures, culverts and sedimentation ponds designed to <br /> reduce erosion potential and allow for suspended sediment to settle out <br />' of runoff water before it is released to the natural channel below the <br /> quarry. In early mining stages, water will pass through sedimentation <br /> <br /> <br />1 7 <br />