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<br />APPENDIX E
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<br />Flood Control Studies
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<br />In order to establish the benefits that could be derived from the
<br />control of floods by \'Jagon "!heel Gap Reservoir and to comply with the com-
<br />ments of New Mexico and Colorado, the Bureau consulted with the Albuquerque
<br />District of the Corps of Engineers. On recommendation of the Corps of
<br />Engineers, the flows at which damages begin were established to be 4,500
<br />cubic feet per secor.d at Del Norte, 2,000 cubic feet per second at Alamosa,
<br />and 5,000 cubic feet per second at Otowi.
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<br />Daily studies were made to determine the capacity required in
<br />Wagon Wheel Gap Reservoir for flood control in the San Luis Valley and in
<br />New Mexico. Details. of these studies are contained in Appendix D - Plans
<br />Considered. These studies established t:1at the 300,000 acre-feet s>f"i;rr:i,-
<br />gation capacity, if operated for joint flood control-irrigation purposes on
<br />the basis of run-off forecasts and space control criteria, would furnish
<br />control of predictable floods in Colorado. However, such operation would
<br />frequently increase peak flows at Otowi, thereby increasing flood damages
<br />in New Nexico. Therefore, additional studies were made in which evacuations
<br />and releases of flood water were not made when the flow at Otowi was 5,000
<br />cubic feet per second or greater, but were stored in capacity provided in
<br />addition to the 300,000 acre-feet of irrigation storage capacity. The
<br />maximum quantity of water thus stored during the study period of 1921-1951
<br />totaled 174,900 acre-feet in 1942. The Corps of Engineers advised that
<br />60,000 acre-feet of capacity would be required for control of unpredictable
<br />floods and that the single-purpose reservoir at the "Jag on Wheel Gap site,
<br />required to provide the flood. control benefits evaluated by that agency for
<br />the plan of development, would have a total of 440,000 acre-feet of storage
<br />capacity. On this basis, the 500,000 acre-feet of capacity in Wagon ~1heel
<br />Gap Reservoir was allocated 60,000 acre-feet to control of unpredictable
<br />floods, 140,000 acre-feet to control of predictable floods in New Mexico,
<br />and 300,000 acre-feet to irrigation and the control of predictable floods
<br />in Colorado.
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<br />Study 12
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<br />In Operation Study 12, the total capacity of ,lagon vJheel Gap
<br />Reservoir was 500,000 acre-feet with the same storage allocations as those
<br />discussed in the previous paragraph under the heading "Flood Control
<br />Studies". The content of Wagon "Jheel Gap Reservoir at the beginning of
<br />calendar J~ar 1925, and the start of Operation Study 12, was 241,000 acre-
<br />feet which was indicated by the. flood control study that started in 1919.
<br />
<br />'" ", '. . Study. ;L2',srioi-Ied'- C()oi:O~aciq I ~ conip'ac~ st:\ltmf",for 'the n:.iear pe'ri~d ,
<br />of ',study; 1925-51, :as' being 19" Years' 'of accrued creil~t, . with a'maximum'
<br />accrued debit of 96,000 acre-feet at the end of 1938, and an accrued credit
<br />at the end of the period of study in 1951, as 86,900 acre-feet.
<br />
<br />The total shortage for the 27-year period of study was 835,100
<br />acre-feet, with an average annual shortage of 30,900 acre.feet or 5.1 per-
<br />cent of the diversion demand. The years that the irrigation demand was not
<br />fully supplied in Study 12 are listed as follows with their corre~9l11iing,
<br />shortages: C. ._ 0'", '..
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