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1.0 INTRODUCTION This Appendix ,provides hydrologic information to support the conclusions of the Biological ' Assessment (BA) for the Replacement of the Plateau Creek Pipeline. Section 2.0 discusses demands projected for the Ute Water Conservancy District (Ute Water or the District) over the next 50 years through the year 2045. Section 3.0 discusses the effects of those demands in terms of both overall depletion effects to the Colorado River Basin and effects to the 15-mile reach of the Colorado River (located between Palisade and Grand Junction). 1 2.0 DEMANDS Ute Water's existing 24 inch pipeline, which extends from Jerry Creek Reservoirs to the Ute Water Treatment Plant (approximately 14.5 miles), has suffered and is continuing to suffer numerous failures partly associated with location and partly due to material failures resulting from corrosion. However, conveyance capacity is also a serious limitation of the existing pipeline and is the primary impetus for replacement. Ute Water's peak day treated water demands are presently in the 11 to 13 million gallons per day (mgd) range while the conveyance capacity of the existing 24 inch pipeline is limited to less than 10 mgd. Thus, Ute Water has an immediate need for increasing their raw water conveyance capacity. With present technology, it is reasonable to assume that a new pipeline conveyance facility can be designed to last for a minimum of 50 years. The BLM, therefore, commissioned a detailed demand study to provide a range of expected demands fora 50-year service life (Pearse & Associates, 1995). The demand study reviewed local and national water and population trends, established population growth projections, investigated effects of conservation, and developed average annual and peak demands for a series of six growth scenarios. From the Pearse Study, Ute Water selected Scenario ' C, which is characterized by a 50 year average annual growth rate of 2.18 percent based on the historical 1950 to 1995 growth. To estimate annual demand volumes, it was assumed that major levels of conservation equivalent to a 17.3 percent total reduction (Pearse & Associates, 1995) would be applied to future demands. Calculating the required level of average annual and monthly demands conveyed by the Plateau ' Creek Pipeline on this basis results in an annual demand of 28,589 AF (in the year 2045) with a monthly breakdown as identified in Table 2.1 and Figure 2.1. J CDM Camp Dresser & McKee ' 0:8047-IIO~DOC~APPEND-B.DOC B-1