<br />XVI
<br />
<br />LETTER OF TRANSMITTAL , \ J'
<br />
<br />4. In general, the agencies recommended the following items of
<br />work:
<br />(a) Rehabilitation and extension of the drainage system of the
<br />Middlc Rio Grande project,
<br />(b) Rehahilitation of the irrigntion system of the Middle Rio
<br />Grande project,
<br />(c) The drcd~ing of 20 miles of river channel abovc the head of
<br />Elephant ButteOReservoir,
<br />(<I) Strengthening and extending levees in the Espanola Valley and
<br />in the Middle Rio Grunde Valley to provide a flood way of 20,000
<br />cuhic feet per second through the Espanola Valley, and a floodway
<br />varying in ""pacity from 30,000 cubic feet per sccond to 42,000 cubic
<br />feet per second through thc middle Rio Grande Vallcy,
<br />(e) The construction of a reservoir on tbe Jemez River with the
<br />capacity of 120,000 acre-feet,
<br />(1) The construction of tlw Ch:unita Reservoir near the mouth of
<br />the Rio Chnma with the capacity of 945,000 acre-feet,
<br />(g) Thc construction of the Chiflo Reservoir near the Colorado-
<br />New l\Iexico State linc with the cnpacity of 816,000 acre-feet,
<br />(h) The degradation of thc river channel by thc release of impounded
<br />flood wat.ers.
<br />5, The constructiou of Chiflo Resermir is not justified because of
<br />the annual cost of the reservoir, to wit., $1,262,248, as estimat.ed by the
<br />agencies, is about three times the total estimated benefit elailued for
<br />prevent.ion of flood dnmnges from inundat.ion and scour above Ele-
<br />phant Butte Rescrvoir, to wit, $384,560, No credit for prevcntion of
<br />inundation and scour bclow Elephant Butte Reservoir can be claimed
<br />for the proposed project, because this inundat.ion and scour will he
<br />prevented by the San Luis Valley project. Only a small amount of
<br />henefit can be claimed for the opemtion of the Chiflo Reservoir for
<br />Bediment control as only 1 percent of the sediment appearing in the.
<br />river comes from above the ChitIo sile, and thig sediment will be
<br />reduced after the construction of the San Luis VI111ey project, It is,
<br />thcrefore, apparent. t.hat the Chiffo Reservoir is not economical.
<br />6. The Corps of Engineers fixed the nUlximUlll permissible flow
<br />throllgh t,he middle valley from spring ftoods at 5,000 cubic feet per
<br />second, The design flood used to fix the flood-cont,rol capacities is
<br />one which has not occurrcd during the 58 ,years, since stream gaging
<br />records have been obtained 011 the river. Neverthele.ss, summer
<br />floods, which result from rninfall on the tributaries of the Rio Grande
<br />and which are not proposed to be controlled by resen'oirs, will cause
<br />floods of a magnitude of 40,000 cubic feet per second or more, It
<br />would appear that the flood ways which pass such floods could, at
<br />infrequent interva.ls, accollnllodate spring floods in excess of 5,000
<br />cubic feet per seeond, FlIrt,he~, it wOllld appear that flows greater
<br />than 5,000 cubic feet per second will be necessary to degrade the chan-
<br />nel in accordance wi th the plans of the agencies.
<br />7, The operation of the reservoirs of the San Luis Valley project
<br />with combined capacit,y in exeess of 1.000,000 acre-feet will substan-
<br />tially benefit, the water supply for the Espanola Vnlley area and the
<br />}'Iiddle Rio Graude area above Elephant Butte Reservoir; v.ill mate-
<br />rially benefit t.hose areas by the redllction of the flood flows, and "ill
<br />esscntially eliminate all ftood damage below Elephant, Butte Reser-
<br />voir. The reservoir capacities recommended .by the two agencies in
<br />
|