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<br />Pinon iOanan floWS directly'thrOugh a portion of the city ofTrin~dad
<br />1:Je'f6re entering th& put'gatoire Rivex". The watershed is shown on plate 1
<br />an<i .the project location is shown oIl,plate 2"
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<br />",4..02. EX:i:sting flood' control wor.k'S,' - Flows from Pinon :Canori at
<br />the present'tirne are conveyed through ,'thio', city qfTrinidad to Purgatoire
<br />River by means of a'drainage ditch anGL:lr11arge culverts, including one
<br />concrete' box'eulvert 400 fee,tlong. ..The capacities of this drainage
<br />ditch and particularly the culvertsar-e wholly inadequate 'j:.o,handle
<br />flood flows., Flash floods from intense thunderstorm rainfall have
<br />gi:'eatly:eiceeded the capacities of th$sedrainage facilitie{3.thereby
<br />'6~jlsing"6verflows and flood damage to; the 'city, Rehabilitation of the
<br />p1tch and. reconstructl.on of the culverts'to ade,qu.ately pass ,flood flows
<br />would': cost considerably more than the' proposed small..,dEltention dam!:
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<br />4":03. Watershed:', '"' Pinon Canol) ~.rrd!/'6, a tributary of theP\llfga-
<br />toire River, 'drains'a precipitous arJ3'a, P{ about<l,,4 fl,quar13 mil'esnorth-
<br />west of the dtyof .Trinidad.Fl!lsh.;tloods from' thiE\area are severE;!
<br />because of steep canyon slopes and SPlU'.se,;.iT.egetal.cQyer:.. The only, out-
<br />let of Pinon Canon to Purgatoire RiVer i~ through a highly developed
<br />resideiit:Lll an'di:bominercial area of'rrinidad. :Small:;i'.\Lpws fpomthe arro:l'o
<br />are,adequately' handled by the present;ditchanq. culyer;l;sbut, ove.rqows
<br />.' train flashflobdscause'considerable damage to, ti);is pprtio\1.of, thel:;lity,
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<br />. "4..04fArea' pr.otecteq.~.- An ares. oi':e;'pqut 4Q'fl:c~e!l.~Qu1dbepr9tec-
<br />ted in tih'e'cit';Y':Of 'Tri!'lidad.' The,.pl;'otect.ed, area..,l~e,s ).n the, -northwestern
<br />,aha 'central secti'onso;f.' the ; city ,'j :Situll.teQ; i" tr,di/l:pI:p;\lected ~ea are .
<br />residences, and business.and. indUstri,ales:j;abli~l}t,s".:,~he, . Atchison,
<br />Topeka and Santa Fe Railway is bridged across .the Pinon' Canon drainage
<br />d;itch:bUtph:YsiM:ld.'lood damate,;to the ,PI'~,tY. ).11;~l)c:>I':' 'l;r;etotal
<br />property valuation in the area protectedj"i'1;,apprQ:p,I!\a~ely ..~:l,B60,OOO.
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<br />5-01. General. - The general plan:;iS('sho~m:..8P,:,pi~te 3 and would
<br />provide for an earth-fill detention danl with ungated outlet to control
<br />flootls frpm Pinon Canon Arroyo, This propoS@9:,'ea!):l<h;"fill dam would detain
<br />all flood ,discharges and provide sediment ret;el!tAQI') :fiI'oma drainage area
<br />of about 1,2 square miles. The plan o!f:~..ill1prcl1!el1\ent::w9.uld not eliminate
<br />all flood damages because of the small uncontrolled area below the dam
<br />which would produce minor flooding d)ll"ing>:v\lry;!iXlt,el"!S~.;.storms.
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<br />5-02, Hydrologic criteria. - Hydro10gic;a.rii;i?t):ierengineering design
<br />criteria utilized in planning the project works 'have been based on the
<br />fact that ass:litahties of complete ,$a:f.'etyU agrl,\1~t',.faill:ll"e of the dam is
<br />necessary because of the distinct ha~ard to life and property created by
<br />locat'ing"t1'1e" dalll" iibo~e 'a populated"':aril"",.,~f"tl;1e., c;l.tY'xQ,f,,/rripic\ad. The
<br />hydrbl<,glLc chllracteristics 'Qf.:: the:,<re:gien; lUl.d;,drii.;\:i\I1I1:~::b,~$iri of Pinon Canon
<br />. 'A.r~o!o,~e:: diSCus;$e~ih detaikl\.n:, Btlpe.nd;i;" I. . Wlfe:idetept:l.on dam is
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