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<br />Normally, ,011 ri v'Or flo,,,s up to 1,500 cubic feet per second
<br />will 00 carried in the conveyance ch~nnel. During p8~iods of higher
<br />~iv~r flow, the quantity 0dmittcd to the conveyance ch~nel ~ay be regu-
<br />L".ted by the gated he2.rling structure C'nd the rdf'aining :low di vGrted in-
<br />to ~le floodway. The irrigati0n releases from Alamogordo Reservoir
<br />\'lOuld be coordinnkd with tho river flows at Art.esia to minimize the
<br />occ"-sions when the combined flows exceed the conveyance ch;mnel c<'Po.c-
<br />ity.
<br />
<br />Proper m,'lintenance of the system r.'ill bG essential. lIc.inte-
<br />neJ1ce of the conveyance chann",l will require the; p<eriodic n,moval of
<br />sediment deposits and the removal or control of weeds ~d plants along
<br />the chc.nnel. The flood"!,\\, lev2', -.rill r"q uir(j m,oinwmmce follo..mg dl
<br />suost<::nti,ol flo1'[s in the flood\'!c.y which "-~ Gxpeckd at fiw,-ye:u' inkr-
<br />v,,-ls. Controlling growth of th8 sf\l t ced~rs is expected to be the chi'~f
<br />mccinten~nce problem in the floodl'laJ'. l'iaintcn,once of th,.. heeding struc-
<br />ture is expected to consist chidly of r"pl~'.cing the temporory dike
<br />sc>ction 2cross the h8c.d of the flood"'2.y which would be overtoIT""d and
<br />brr;c.ch-cd 'ahen GXCC;SS flows c,re dh'C~ted into the flood:',ccy. ~(".jor rep,cirs
<br />to the syst8m mllst De m"-,,e in the. 8V(mt of floods gr,,'<,t:.'~ then the d"sign
<br />c.op~city of tho project. In vi"", of the: prob2.bility of selch floods, the
<br />plan for mp.inton~.nce provide:s fo~ rc,.,lc.cinr; one-third of the floodm:!y
<br />levee <1nd the convcynncc channel once every 2.5 YI'::clrs. The possibility
<br />of [l m~jor flood occurring ':!ithin th" first f'.-vI ye."lI's of operation be-
<br />fore a sufficient ~cintennnce reserve h~s cccc~ul~tcd ~ust bo ~ccognized.
<br />
<br />Ample opport~~ity exists for ir~ig~tion US8 of ell of the
<br />",,-2.tcrs '.vhich cot'1d b8 s81vrcged unoe~ tho proj")os,~:d plM; howc,vc,r, specific
<br />cssigrunent of th" sl'l';c.g"ccblG "'2tcr, .1 future TtCsponsibili ty of the
<br />Pecos River Commission, is imp':'c.ctic.".bl., c:.t t!lis time. Th8 v21ue of
<br />th..: s"lv.'l'~e ',';'lkr for irrigc,tion use r;.1S det~m,ined by cv.cluc.ting the
<br />benefits th"t Y!ould result from its llS'c. The diNCt, indirect, :end
<br />public b8mfi ts from the irrip,.,tion US2 of the. s.o.l vp.ged 'P.tor nre
<br />~ou"hly rstimp.tcd to tot".l 2.bout ':930,000 .cnmwlly, -;;hicb !';rsntl:r ex-
<br />ceed the estim:cted o.nnunl costs, "!ith dirc'ct or pri",o.l''j" h:on"fits eX-
<br />ceeding tho costs in ,". rntio of 1.6 to 1.
<br />
<br />The 8stim.:ot,'d benefits, how;,'.'er, do not t'tk,-. into o.ccount
<br />.-my possible n"gc.tiv" ef:',.ct of the incr(.,cscd r.ote of depl,..,tion of
<br />tho stort,ge cccV,ci ty in l!cHill'tn Ruscrvpir resulting from th3 proposed
<br />dev010pment. The scope of the hydrolo~ic cnl1 eV".lu."tion studies re-
<br />quirod to est~01ish the net 8ffcct of acccle~~tcd scdim8nt~tion ~d
<br />the? vdue of t.ho r,:siduccl c.c.p'lcity of the rc s0rvoir far streOJ'l r'~gu-
<br />1 "tion is of such mo.r;ni tud" ..s to m~l{o it imprc.c ticC'blr; of ,c.ccomplish-
<br />mcnt c.t the prcs'.mt tim.,. It is not c.nticip~tc:d, hooKvcr, 'th,c.t thG
<br />~e?sults of such studies uill sis;nificnntly chc.nge the; c.stim,ct.:od bencfit-
<br />cost r~tio. The :,nvcstlg,.,tion of opportunities for eff"ctiv,-; tc:rminC'l
<br />sto~p.re:e for the: Ccrlsb~d proj.,ct h'l'" b.::en nssign::d ,., high priority in
<br />the e01nmission's prOf!ram now in progress. -
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