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<br />Is cal i brated us i ng the colI ecteddata, I twi 11 then be used to est I mate fu.
<br />:ture stream conditions for p.rojected populations and waste-treatment plant
<br />e f fIc 1 en doe's ,
<br />
<br />The steady-state model as desc'rlbedallows either: '(1) Esti'mation of the
<br />streamreaeratlon .rate (K2) .by usl,ngaverage dep.thand .veloclty relationships
<br />for the reach, or (2) dl rect measurement of K2' For the"Y'ampaRIver study, K2
<br />may be measured .uslngaprocedure developed by Rathbun,Schultz, and Stephens
<br />(1975), This procedure uses propane or ethylene as an I.ne'rt~gas tracer that
<br />Is injected at a given concentration level at an upstream location, The gas
<br />concentration is then measured.atdeslred stream locations.below the injection
<br />po'int, As noted .byRathbun, the ave'ragegas-tracer loss rate to the atmos-
<br />phere is In di rect proportion to the ave'rage reaer.atlonratefor that reach,
<br />A laboratory procedure for the ana lys i sof .thegas tracer' (Schu 1 tz and others ,
<br />1975) has been .deve'loped.
<br />
<br />Th I s study wou I d expand on'cthe bas j n water-qua 1 ity'management p I an made
<br />previously by a consultant for the .ColoradollDepartment of:;Health .as part of
<br />the U,S, Environmental Protection,Agen.cy'..ppequlrement under section 303(e) of
<br />the Federal Water Pollution Control Amendments of 197Z (PL'92-500). The Yampa
<br />River basin assessment will augment this previous study and will aid the U,S,
<br />Environmental Protect ion Agency In ,are-awl dewaste-t reatmentmanagement studies
<br />(TerryAnderson,or,alcommun., 1975)..presentlybeing conducted In the Colorado
<br />counties of the basin,
<br />
<br />
<br />S'edlment Transport
<br />
<br />A :potenti-al h,'criti ca 1 Jmp,act'resultlrtgfrom str j'p"m,l:n ing .ofcoal is land
<br />:denudaHon..and "the transport 'Ofs.ur'ficlalso 11. materia ltl1rough air and water ,
<br />'.S,econdary .effe'cts;contr Ibutin.g ,.:to'further -S'O 11 'eros ton 'i,n:clude the following:
<br />
<br />a.. ConstF.:lJc.t:i,conofroads, ,'ral II i'nes, :'reservo i .reS, .:p'owerp I an.ts, and
<br />;'plpellnes,;
<br />
<br />b. . Urbang'rlQwth, ':such ;:as ';const.puct Lon ..of pI' Iv.ate .'homes, and pub I i c' and
<br />,commer'.c,kli:l : bu i lei 1n:gs.;
<br />
<br />"c, A1ter.at:licms in 1and~,use_'and:mal'l:a.gement, lncl'udJl'\glogglng, gr'azing,
<br />Jdry-Ian'd if:a'rmlng ,anid 'i:ror'l:gate:eI :.crQplands,
<br />
<br />dAsdhe'Y.ampa';iRiver .basil,ni:s :.a 're:liatively ,wate-r-de'n:d.hent .reglon, I ncreas-
<br />-oes j,n;li'edlment' blIa'.dlngsinthe ,.st'p.eiam'sy.s.tem:mayadvers<el'y 'i1Hec t 'direct ut il-
<br />d..z.a't:Lon .of,'surfa:ce""water "l'eS:Ol:mce.s, l1h.es<!Ja..dvel'se:..effectswould extend to
<br />'lilll\.s,t:ream "'resel'v.6hrs ..,an,d .to.at;:tamvts .:to''.IJP!!l'nade'land .,use ,lnselected ,a'reas, for
<br />"'elltaillple "by ',c~mv,e'ttt:j.llg land fram .'gr;az Ing'tolrr legated cmcpplands.
<br />
<br />'"Recards . 'of ,dally '.s.edimen.t.,:con'cerrtratlliln.and load.'downstream of outflow
<br />po.Fnts 'of theYampa'River and the Little Snake River subbasins 'are few and of
<br />.short duration. '}Dally sediment creco'r,ds'on the Green .River mainstem above and
<br />b-dow.tihe 'con f ,1.,uenlle M.i t.h "tnetYfampa-Ri vel' ,'may he ,of s ome:.as s i stance,
<br />
<br />,.~Bot:h,b.as,knw:,hlle'and'site~.s;li'edfl:.c ;.sed;lment~mode IJllgrs:tudies 'ar.e proposed
<br />'far. ;hn..cl'llsihiXl'l i[jind,he .'basi:n.asses,smen to '-Aval'la.ble,mode 15 ;"for p_os sib 1 e appl i ca~
<br />
<br />,2.0
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