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<br />wllS ~stimated by "flood occurrence-damage aualysie~ Stage~
<br />damage curves for disparate floods were constructed and were based,
<br />,on damage survey data. A summation correlation of stage,damage
<br />and stage occurrenc,e for the dissimilar floods gave an indicated average
<br /><of annual benefits of $29,650.
<br />82. Aver'fge annual be"efits ~agricpJ,tural.-crops, lands,andimprove-
<br />ments. -Losses resultfug from caving 'banks 'have 'not been consid'ered
<br />as a prevontable loss. The losses to' the agricultural lands and im-
<br />provements result prfucipally from damage to crops; destruction of
<br />fences; deposition of sand, gravel, and debris; and erosion of top soil.
<br />The 'average annual prevention of flood damages has been bllSed on
<br />thenssumption that the.chron~lo!:ical o~currence and also the, magni,
<br />tnde of future floods Will be Similar to that of pllSt floods of record
<br />,above 15,000 cubic feet per second (bankfull stage). Floods of less
<br />than 15,000 cubic feet per second produce no flood damage under
<br />present chanael <,-ouditions. Consideratioa has been given to t)1e
<br />type of flood and the time of year in which the flood occurred, in
<br />determining the average annual b~nefits to crops, lands, and improve~
<br />ments which were computed lIS $834. '
<br />83. Avera.ge annual bendi,ts-transportation facilities, agriC1.dtural
<br />area.-The flood damages to transportation facilities in the agricul-
<br />tural area of the flood plain, whieh does not include the urban area of
<br />'Trinidad, have been erosion of highwaY'embankments due tooveiflo'w,
<br />bridgr.s, and railway property. ,The nverage annual benefits, whieh
<br />were estimated in analysis similar to those for Trinidad, were com-
<br />'puted as $1,611. '
<br />84, Average annual. benefits-irrigation structures.-The average
<br />annual benefits for irrigation structures fu the agricultural area give
<br />consideration only to those damages occurring to permanent irrigation
<br />structures, for floods exceeding bankfull stage, or 15,000 cubic feet per
<br />second. It is considered that all benefits accruing for discharges of
<br />less than 15,000 cubic feet per second will be irrigation benefits.
<br />'The average annual benefits were estimated in a similar manner to
<br />those for Trinidad. The estimated average annual benefits com- ,
<br />puted were $4,561.
<br />85. Irrigation benefits"CTflood detention.-The United States Depart-
<br />ment of the Interior, Bureau of Reclamation, has estimated that the
<br />benefits derived from a supplemental supply of water (water saved
<br />for irrigators) made available, to lands with annual shortages by
<br />operation of' Sopris Reservoir, reducfugflood flows to a inaximiun' of
<br />700eubic feet per second, would be $5 per acre,foot. It was also
<br />estimated that approximately 5,540 acre,feet per year, with a deten"
<br />tion pool of 5,200 acre,feet, will be made available to about 15,000
<br />acres of land having an annual shortage. The average annual
<br />ben,efits would be $27,700.
<br />86. Irrigation bendi,ts-less than bankfullstages.-Areservoir at the
<br />'Sopris site would, by regulatfug those channel flows which now
<br />damage or destroy the minor brush and rock,irrigation dams, reduce
<br />the annual maintenance for those works, thus resulting in a further
<br />benefit to water users. The estimated annual value of this benefit
<br />is $4,000. '
<br />, 87. Bendi,ts-enhancement qf values.-The area subject to flood
<br />damage was investigated for possible enhancement of values which
<br />might, result from flood protection. An estimate of the probable
<br />enhancement was bllSed on field investigation and interviews in' which
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