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<br />tll<' l"wet r~"ches of the "'~ter"hed wl",~e " sUght .1<>ouat ~f addUion"l
<br />run.off ha_" ",ioor cHea on the magnitude of llIaJor flood flow. (Le., the
<br />lOo-ye,H frequency flood), ~nd (2) the ""'jot portion of runoff originates in
<br />the S~'l habel National Forest wher... a small .1moll:U of land use chang~ ta
<br />
<br />TheO\ct cre"ted a coop...rat1v" progr"",of tnsuranceagal1"stfloodda""'ilehy
<br />the private flood i'lsurance 1nduHry and the federal sovern""'nt.
<br />
<br />OEBRtS !'LOW (MUllfLOW) POTENTIAL
<br />
<br />.,ntlc1pated.
<br />
<br />Of uelllO.H tltlporeance t" the P<'ssibitity of encroach1llent on the edstitl.g
<br />floodplains, O"velop"",nts Io'ith.1n the flood pla10 could obstruct the flow
<br />of flood Io'ater, ralse the flood elevations, and create ha7.ardoll" velodt1es.
<br />Etl.c...oachment is a far more sigtl.ificant f.."eor than the ad,ll~ional runoff
<br />created by proposed upstr<,<~", developments.
<br />
<br />Thc area north of and abovc theCbaikCreek flood pla1nLnr..acbes4, i,and
<br />61" snbject to debris flows (mudflo",s). !1azardous condHlons 1:1 thls area
<br />are llnlqlleand sep>!.rate fromflo<'ldingtntheChalkCreekfloodpla1tl.. These
<br />conditIons ,~re classIfied 'lS 0\ geologic hazard and defined In Chaffee
<br />County's zonIng resolut10rlS page 26.
<br />
<br />The National Flood Insurance Act of 1968 (Ittle XIII of the Houslng and
<br />Urban Dcvelop::>c[\t Act, P.L. 90-448) recognIzed the necessIty for flood plain
<br />,"an,~gement. This .lct .'akes f<!-derally subsidhed tns"ra",cc avatlable to
<br />cltirens to co",mmlltIes th.ot :1dopt regulatIons controllIng future develop-
<br />::>"'lts of thdr n"od pLatn. L[\ res~ect to ennO>lcllrTl<'",t on the flood platn,
<br />thereltulatlons requLre:
<br />
<br />Thllsfar,debrlsflowproblemshaveb<!enconf1nedtothelnterruptlonof
<br />trafficonStatefl1glllo'ayI62, however, so"", of the Uows have co"", close to
<br />reSIdential homes and cabins. One flow 1tl. partIcular, located to the south-
<br />>lcstofflou'ltPr1ncetunll,)tSpri'lgs, has b<!etl." continu1ng OIaIntenatl.cep...ob-
<br />le..forhLghwaycre...,s, Onsevetaloccasto'ls,thehlghlo'"yh..lshc.enblocked
<br />",tell debris, crcIltIrI.'l" hazard to .."todsts. The flo.. can last for several
<br />hours "",k1n~ Lt Imllos81ble to :rove cmer~ency .....111,,1"8 ineo or out of the
<br />
<br />area.
<br />
<br />N~Io' r,,"lden~ L..l conattuct ton Ot sllbst<lnt tal tmprovc,"ent of exlst Ing
<br />homes llIust haw the Iow"s~ floor levd ~bo"" the e1e~"tion of the
<br />
<br />!OQ-y".,rf1ood.
<br />
<br />Unfortllnatety, th~ Chalk Cll ff dcbrls f10lo's "re e"t"""ell nnpredlct1l.ble ""en
<br />thought of in terms of frequency of occ"nenc~ SLJch as 10-, 'i0-, or I00-ya~r
<br />"vcn~. H:l8tortcaI data of amount8 and depths of flow are n,mcdstent and
<br />H~tistkel .~naiys,," ~\1cb .~s tho~e co",mo"ly used in flo<>d fre'1"en~y deter-
<br />::>t"at\ons cannot be "ppLied ...Lth reUoble confidence. UnHke a o.cllnHrean:l
<br />-'lood pla1n, ~"'edlcUon <>t fll~urc d~brh flow p.~th" Is c,,~remely unrcllnble
<br />duo, to tile """,h.'r of vadablc'~ lnv"lv~d, Ooebri. fan M~ard are"". ~"rth of
<br />Outk Cteek .,,~ delt",,_~t~d on n~"r"$ 1 :,nJ 2,
<br />
<br />~o"-re.identtal c"n~tru~tl"n ml1at ""-'~t the S"me 8t~ndard or b.J floud
<br />[>roofed to that l~"el.
<br />
<br />Th,' 1%8 act he"ef1~~ \J~'n~r.. of s~ructur~~ "lr~"dy In ~h~ f1ood-r,o"~ .1r~ag
<br />by ;ruvlJi"g tLlsllr.."~~ ~h." h.:J M""n ",\.,v.~l!"h\~ t~lr",,~:. pr1vHc c,,"'pat\les,
<br />
<br />"
<br />
<br />20
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