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<br /> <br />t' <br /> <br />-. <br />, <br /> <br />the same time the discharge at the gaging stations near the mouth of <br />the Conejos is such that shutting off diversions of these magnitudes <br />would not result in exceeding the 1,500 c.f.s. channel capacity, <br />closing the headgates of ditches on the conejos proper for one week <br />would result in an amount of water at the state Line of between 15,000 <br />'and 19,000 acre-feet in addition to the runoff which might otherwise <br />be expected. An analysis of the records for 6 years, in which runoff <br />on the Conejos was approximately that which has been forecast for <br />1965, indicates that in 5 of these years there were consecutive periods <br />which would meet the above criteria for 16 days or more, either on the <br />rise to or recession from maximum peak runoff at Mogote. In the other <br />year studied there was less than one week when such conditions pre- <br />vailed. However, in that year the deficiency for the Conejos was only <br />9,000 acre-feet. cessation of diversions from the San Antonio for one <br />week when flood conditions would not result, would provide an addi- <br />tional 1,200 to 1,500 acre-feet of additional delivery. During years <br />of runoff greatly in excess of average, a second closure of headgates <br />for a few days would assist in compensating for years of below average <br />runoff. <br /> <br />winter Diversions. The recorded diversions from the Rio <br />Grande for the months of November, December, January and February have <br />averaged about 14,000 acre-feet per calendar year from 1952 through <br />1964. If these diversions were foregone, that amount would also be <br />available on the average to meet annual scheduled deliveries. <br /> <br />Runoff Forecast for 1965. The Weather Bureau forecast <br />based on March 1, 1965 conditions, and normal precipitation for the <br />remainder of the year, indicates a water year runoff of 740,000 acre- <br />feet for the Rio Grande near Del Norte, and 275,000 acre-feet for the <br />Conejos River near Mogote. These amounts would compare closely with <br />the runoff conditions which occurred in the years 1958 and 1962. The <br />difficulty in attempting to apply foresight in meeting exact delivery <br />requirements in anyone year may be pointed up by comparing the year <br />end results in those years. In 1958 there was an over delivery on the <br />Rio Grande schedule of 22,100 acre-feet. On the Conejos there was an <br />under delivery of 9,000 acre-feet, with a net credit of 13,100 acre- <br />feet for the State of Colorado. In 1962 there was a debit of some <br />87,000 acre-feet, divided about equally between the Rio Grande and the <br />conejos. Runoff conditions in the preceding year appear to have a <br />bearing on the deficiency to be expected in the following year. In <br />the case of 1958, the preceding year was one of much above average <br />runoff, in which a large debit of 156,000 acre-feet was incurred. On <br />the other hand, 1962 was preceded by a year with runoff slightly below <br />average. With regard to the prospects for a deficiency in 1965, it has <br />been preceded by a year of runoff much below average. It is thus not <br /> <br />Memo <br /> <br />-3- <br /> <br />April 2, 1965 <br />