2009-12-18_REVISION - C1981008 (4)

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in the ET calculations provided by Western Fuels were developed in central California, whereas the values used by NRCS come from the Colorado State Agricultural Research Center near Cortez, Colorado, arguably more representative of climatic conditions in Nucla, Colorado. Secondly, the Blaney-Criddle method is designed to estimate seasonal consumptive water use of agricultural crops, not short-period consumptive use. "Peak daily" consumptive water use, one of the values that the NRCS uses to design irrigation systems so that crops can survive the "heat" of the summer, is a short period (10-15 days) value. As explained on page C0683-2 of the Colorado Irrigation Guide (enclosed) the Blaney-Criddle method needs "modifications" to estimate short-period consumptive use of crops. The NRCS, using empirical data from field trials, has modified the Blaney-Criddle procedure to develop its peak daily consumptive water use for various crops. The NRCS hereby restates that 0.25 inches per day is the peak consumptive water use of alfalfa in the Nucla area. This is the value that I stand by and have used in designing the irrigation system appropriate for the Morgan property of New Horizon Mine #2. The bottom line is that Western Fuels and Greg Lewicki & Associates have used unreliable data, and over-simplified the procedure for establishing ET values and Peak Consumptive water use of irrigated alfalfa in the Nucla area The next issue to contest is the analysis presented by Western Fuels regarding the "Available Irrigation Water for Siderolls on the Morgan Property," Attachment 2.05.4(2)(e)-7-6 through Attachment 2.05.4(2)(e)-7-7. I addressed this issue in an earlier letter submitted and dated March 21, 2008. Western Fuels argues that 50 shares of Colorado Cooperative (CC) Ditch Water does not provide sufficient water quantity to adequately serve three full quarter-mile length sideroll sprinklers, particularly in the month of July during peak consumptive water use by the alfalfa crop. The NRCS design indeed calls for 0.5 cubic feet per second (cfs) per sideroli, a total of 1.5 cfs, during peak consumptive water use by alfalfa in the month of July. And Western Fuels correctly calculates that the average quantity delivered by the CC Ditch from 1997-2007 per 50 shares in the month of July is only 1.39 cfs when flows were capped at 1.5 cfs. But for all practical purposes 1.39 cfs is adequate to service three full length (quarter mile) sideroll sprinklers. If you divide 1.39 between three siderolls, then each sideroll would get 0.46 cfs. This equates to 6.3 gallons per minute (gpm) per nozzle as apposed to 6.8 gpm when each sideroll receives 0.5 cfs; an insignificant difference. The minimum flow necessary to maintain pressure in the sideroll sprinkler is 0.42 cfs which is met with the 1.39 cfs average. But an average calculation does not tell the whole story. If one looks at the data provided by Western Fuels regarding CC Ditch delivery of 50 shares in the month of July, Attachment 2.05.4(2)(e)-7-16, one sees that the average was greater than 1.4 cfs nine out of the twelve years, and the average was greater than 1.4 cfs seven out of twelve years. Historic crop yields in the Nucla area reflect this variation in water delivery. Alfalfa, as with some other crops will go dormant in the heat of the summer if water is not sufficient, but the crop will survive unless irrigation water is completely absent. In fact, of more concern in growing a successful alfalfa crop is over- irrigation, which has the potential to kill the plant. The NRCS design for irrigating an alfalfa crop with a sideroll sprinkler using 0.5 cfs is inherently conservative and has margins of error built into it. With good fanning practices and proper irrigation water management 50 shares of CC Ditch water should be sufficient to supply three full length sideroll sprinklers, servicing 71 acres, and grow a productive alfalfa crop that meets the average yields established for bond release.