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<br />'L <br /> <br />( <br /> <br />2 <br /> <br />: ~::~- <br /> <br />35 t 360 ..ac~es of full ~er..'ice l.:tnd. for n:unicipcl and inut:Strial use. and - ;_~:i! <br />for fish lind <."ildlife7cnhance::l8nt. Part- of the "ater "ould also be provided <br />for the Ute Hount2-in Ute Indian Reservation. Tile project ,,",ould ,inch,de <br />recrestion~l facilities and acquisition and devalopnent of land for "ildlife. <br />Sr~.uelt floods on the Dolores F~vcr would be 'controlled. A 9-year construction <br />p~~iod is anticipated. <br /> <br />li..\SIS FOR OPIHION <br /> <br />Jeopardized Species....... <br /> <br />Tne Colorado squawfish', hlID?back chub, and bony tail chub were once abuI'ldant <br />~hroughout the Colorado P~ver System fron the Gulf of California to southwestern <br />:~o~nb' ,Presently the squcwfish is limited to the upper mainstem and <br />~jor tributaries of the Colorado River System. The hunpback chub and the <br />bo~ytail chub are found only in li~ted areas w"ithin the river system in <br />Color~do, Utah, and Arizona. The pri~ry cause of decline for these fish <br />species is hUDan alteration and degradation of thc river en_"ironment, <br />l~jor 2n?ound~ents and ~ater diversions have depleted vater supplies and <br />altered te~erature, turbidity, and strean flows~ thus reducing habitat for <br />endeo:dc fishes. <br /> <br />A less i=port~~t cause of decline may be the increased ,n1~bers of eY~tic <br />fishes such as carp and channel catfish, but: thiG increase in exotics is <br />also a f~cticn of habitat chanbes. Although co~rela~ions eY~st between <br />declining native fish populations and increasin& populations of exotic <br />fish, cause n~d effect are not fully undc~stood. EDwever, ~e believe th~t <br />if the river wore closely resembled its natural state, fewer e}~tic fishes <br />,..auld be present. <br /> <br />,',-- <br /> <br />We do =t know 21.1 the specific requirements and exact distributions of the <br />Colorado aqua.-fish, bonyt~ chub'; and hu::rpback chub. This is true partly <br />because these fishes, as for nest rare species"have been of little interest <br />to society until recent years. Also~' these fishes are difficult to capture <br />or obser;e because the vaters they inr~bit are usuel1y's."ift and turbid,and <br />acce8S to Dany of the canyon reaches is licited. Bowever,.~e are intensively <br />studying the endangered fishes of the Colorado and Green Rivers and have <br />described the Fish and Wildlife Service's (FHS) intensive study of the <br />fishes in previous biological opinions: Upalco, Dallas Creek, ~~d the <br />S:rawber~' Aqueduct ~~d Collection Syst~. <br />..... <br /> <br />Tne pr'-nry area of concern in this opinion is the Colorado ?~ver f~~~ its <br />=r..:luence '.'ith the Dolores P~ver do.mstre.!llD to lUte ~!E.rina (appro::iJ:.ately <br />142 river Diles). At present; ~e do net have sufficient data to sho~ the <br />Dalo=es ?~ver itself is essential for recove~' of the ~lcrado sq~~ish, <br />r.t:....~oecr: chub, or bonytnil c..~ub. Also, records do not icie::J.tify the Dolores <br />River as i=~ort~nt habitat ~foi.these three specic5. Therefore, we are <br />cc~cerned pri~rily w~th Color~do .r~ver habitat do~~stre~ of the confluence <br />of the Dolores aad Colorado "P..1vers. . <br /> <br />..~..1 .: <br /> <br />"' <br />