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<br />89. Project justijication.-The benefits which might accrue from
<br />prevention of floods for any project or combination of projects, in
<br />the area under consideration, for floods of probable occurrence equaled
<br />or exceeded per 100 years' are given in the preceding paragraphs.
<br />90. The average annual benefits accruing to a dual,purpose reser"
<br />voir at the Sopris Dam site, which would provide flood protection for
<br />a probable flood occurrence of once in 100 years, would be $80,671.
<br />This amount includes the total average annual benefits in the urban
<br />area of Trinidad, and the agricultural area from Sopris Dam site to
<br />the head of the canyon section as given in SUlrmary of Average Annual
<br />Benefits, table No. 11. ' The annual charges for she project are $176,-
<br />'000, (See appendix D.) 1 The "atio of average annual benefits to
<br />,annual cost is 0.46, and the project is not economically iustified,
<br />91. The average annual benefit~ accruing to the dual-purpose res,
<br />'Orvoir, which would provide the ,greatest ratio of benefits to costs,
<br />were evaluated by assuming that tbe total benefits would include those
<br />irrigation benefits by flood detention and the )?revention of flood
<br />.Jamages up to and including' probable flood dIscharges of 19,700
<br />'eubic feet per second. ' The average annual benefits were $31,425.
<br />'The annual charges for the project are '$61,600. (See appendix D.) 1
<br />It is apparent that with a ratio of benefits to costs of 0.51, the project
<br />is not feasible at this tune,
<br />92. A reservoir, at the Sopris site for 'flood control only would;'nb~
<br />be feasible. This is evident from the low economic ratio for the dual~
<br />purpose reservoir which would control a' probable flood occurrence
<br />,of once in 100 years. Of the benefits attributable to the dual,purpose
<br />reservoir, 39.3 percent are irrigation benefits. To control a flood with
<br />a probable oecurrence of onee in 100 years would require a reservoir
<br />eapacity of about 28,400 acro-feet' for the dual,purpose structure.'
<br />Only 5,200 aCl'e,feet of this total are allotted for irrigation detention.
<br />,It is therefore obvious that the capacity for ,a flood control reservoir
<br />would not be substantially smaller than for a dual-purpose structure.
<br />Also such a structure would have a small ratio of benefit to eost.
<br />93. Investigations for several channel designs through the urban
<br />area of Trinidad indicate that none of the designs would be economi-
<br />eallyjustified. The economic limits of the various designs aregiven on
<br />,chart No.1,' a)?per'dix A. It will. be noted that the break in the annual
<br />charges curve mdlcates a change m type of channel' ,
<br />94. It is evident that a combination of a reservoir for flood control
<br />()nly ,or a dual-purpose reservoir 'at the' Sopris site and a channel"
<br />improvement through Trinidad would not be feasible. The most eco-
<br />nomical dual-purpose structure at the Sopris site is not feasible, and the
<br />improved channel through Trinidad with the greatest rat,io of benefits
<br />to cost is not economically justified. Therefore, a combination of
<br />the two struetures for prevention of flood damages is not feasible,
<br />95, An'inspcction of chart No. 1,' appendix A, indicates that a
<br />,ehanncl improvement through Trinidad with a design capacity of
<br />45,000 cubic feet per second (deseribed in par. 78) would have a ratio
<br />()f benefits to cost Of slightly less than 1 : 1. Therefdre, construction
<br />d this project is not economically justified, but, considering the
<br />national economic importance of the railroad facilities and the welfare
<br /><lfthe ~ity of Trinidad, the project is warranted.
<br />
<br />1 Not printed.
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