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<br />-;: - <br /> <br />e. At the top of page IV-24, the average unit runoff of 24.49 acre-feet per square <br />mile for Grand Mesa streams is applied to the "collection area" (of 20.85 <br />square miles?) to obtain a value of 6,077 acre-feet per year. The numbers just <br />don't work out. <br /> <br />f. In the conclusions in the second paragraph on page IV-24, the average-year <br />yield is apparently based on a preceding mathematical error and the dry-year <br />yield figure of 1,260 acre-feet has not been explained in any of the preceding <br />analyses. <br /> <br />12. It's questionable whether either method used to estimate basin yield is correct. <br />Method I may be an average of wet years and Method 2 attempts a correlation <br />between basins which may not have similar characteristics judging by the unit runoff <br />figures in the Rice tables. As the feasibility study suggests, it may be more <br />appropriate to attempt a correlation between a smaller number of basins with greater <br />similarity in physical characteristics. If that type of correlation doesn't appear reliable <br />(based on statistical analysis) then it may be necessary to use a form of stochastic <br />hydrology to estimate basin yield. <br /> <br />13. In addition to basin yield, the concept of system yield needs to be investigated. Both <br />physical and legal availability of water as well as system characteristics and facilities <br />need to be considered in the system yield analysis. The report fails to link the <br />physical and legal availability questions and lacks an operation study using suitable <br />time increments over an appropriate period of record to estimate the dry-year system <br />yield to the Town from the Town's water rights with the existing diversion and storage <br />facilities. This type of analysis (the system model) can also be applied in the <br />evaluation of the yield of alternatives for new facilities. <br /> <br />14. The basin yield and system yield estimates appear to be critical issues for this study in <br />view of what may be a fairly limited supply of water from the Rapid Creek Basin. It <br />may be questionable whether the water supply in the basin is adequate on a dry-year <br />basis for the Town alone in future years. Sizing facilities to provide water to other <br />entities may not be feasible except for very short-term situations. <br /> <br />15. In the development and evaluation of alternatives in Chapter V, no mention is made of <br />conservation as a method to manage demand and thereby reduce the size and cost of <br />new facilities. <br /> <br />16. Chapter V badly needs maps and schematic diagrams to show relative locations of <br />existing and proposed facilities and to indicate how the alternatives would function. <br /> <br />17. On page 5-18, on what is the estimate of the 1.75 mgd capacity for the existing <br />pipeline based? <br /> <br />-3- <br />