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<br />~ Under this scenario you would make the following <br />comparisons. <br /> <br />Table II Seasonal Water Budget for On Farm Irrigation <br />McElmo Creek Salinity Control Study <br />(acre feet/yr) <br /> <br />Item <br /> <br />Irrigation Supply <br />Group Ditch Seepage <br />Farm Delivery <br />Onfarm Ditch Seepage <br />Gross Application <br />Net Application <br />Deep Percoluation <br />Ta il wa ter runof f <br /> <br />Future W/o , <br />S<>.2A "" ~ p..., ~ <br /> <br />l2l.000 <br /> <br />3.000 <br /> <br />118.000 <br /> <br />4.000 <br /> <br />114.000 <br /> <br />54,000 <br /> <br />lO,OOO <br /> <br />50.000 <br /> <br />Selected <br />Al t. 5 ~ Historic <br />~~ \.\.0 <br />77,000 107,OOO <br /> <br />o <br />77 . 000 <br />1.000 <br />76.000 <br />54.000 <br />7.000 <br />l5,OOO <br /> <br />2.000 <br />l05.000 <br />4,000 <br />lOl,OOO <br />47,000 <br />9,000 <br />45.000 <br /> <br />Under the historic condition the tailwater runoff is <br />estimated to be 45.000 af/yr. The average annual flow of <br />McElmo Creek near Cortez. according to USGS records is 41.080 <br />af/yr and the average annual flow of McElmo Creek near the <br />Colorado-Utah State line according to USGS records is 35.790 <br />af/yr. Thus. it is fairly reasonable to assume that if the <br />water budget is correct, most of the flow in McElmoCreek at <br />any point in time is the result of irrigation return flows and <br />furthermore. most of the irrigation water is diverted from the <br />Dolores River. <br /> <br />~ <br /> <br />Thus. if you are looking at historic stream flow conditions <br />on McElmo Creek versus what they would be after the USDA onfarm <br />program is implemented you should expect to see something less <br />than 15,000 af/yr or a net depletion to McElmo Creek of roughly <br />30.000 af/yr. It should also be noted that any depletion <br />McElmo Creek sees should correspond to increased flows in the <br />Dolores as a result of less diversions <br /> <br />With the delivery of Dolores project water. which will <br />occur in the near future, you should expect to see roughly a <br />5.000 af/yr increase in McElmo Creek flows as the result of <br />increased late season diversions which will alleviate existing <br />shortages. Therefore. if you install the USDA project one <br />could argue there would be a 35,000 af/yr depletion to McElmo <br />Creek. <br /> <br />. <br /> <br />-2- <br /> <br />OC~lC7 <br />