2009-12-18_REVISION - C1981008 (4)

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As you can see from the water budget, under "normal" weather conditions about six irrigation events are required throughout the growing season to meet the water needs of alfalfa: one in May, two in June, two in July, and one in August (if enough irrigation water is available, then two irrigations could be scheduled in August, or one in August and one in early September). Below is a table which lists the average consumptive water use of alfalfa growing in the Nucla area, and the time it takes for the crop to consume 3.8 inches of water, or in other words, the time between irrigation events: May June Jul August September Average Consumptive water use of Alfalfa 0.12 0.18 0.22 0.19 0.12 In./Da Time Between Irrigation Events 32 21 17 20 32 (Days) . In my sideroll sprinkler design I used a peak consumptive water use of 0.25 inches/day, slightly higher than the average consumptive use of 0.22 inches/day that you see in July -- again, I have designed conservatively to meet the potential extreme temperature conditions. What needs to be stated here is that in both the months of May and September only 1 cfs is really needed to irrigate the alfalfa crop sufficiently since the turn-around time is 32 days. Two . siderolls, each using 0.5 cfs can xun simultaneously for 13 days to irrigate 46 acres, then they can be shut down and the third sideroll, using only 0.5 cfs, can be run to irrigate the remaining 23 acre field. I've also included a spreadsheet that lists the average monthly delivery of CC-Ditch water to the Nucla Park for the last ten years. I've factored in ditch delivery loss of 12%, from information provided by Dean Naslund, CC-Ditch Company Superintendent. I have a column for the quantity of irrigation water that 50 shares (the amount leased to New Horizon Mine by the Morgans) would equate to each month given the amount of water delivered. And per the above discussion of irrigation scheduling for alfalfa growing in Nucla under the three sideroll sprinkler system, I have included a "Target" column for the amount of irrigation water needed each month. _ Finally, there is a column listing the difference between the 50 shares of water delivered and the amount needed to irrigate alfalfa sufficiently. As you can see from the difference column, in the last ten years there have only been three months out of fifty that the CC-Ditch Company was not able to deliver, by any significant number, the "target" quantity of irrigation water needed for our system. The three months are June-1997, July 2002, and August-2002. As most of you know 2002 wqs a severe drought year, with some of the driest months on record. You may wonder why I did not list July-1998 and July-1999 as months that were "significantly" under-supplied. In both of those years the difference in water delivered and water needed in July was only -0.11 cfs/day. If you spread this deficiency among three siderolls, each sideroll will still have available 93 % of its design capacity, and the sprinklers will still work -just a little less water will be applied! In August of 1999, another deficit month, the CC-Ditch was shut down for some time due to heavy rainfall events (personal communication with Dean Naslund, CC- Ditch Superindendant), in which case farmers probably did not need to irrigate their crops.