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<br />76 National Water Summary 1984-Hydrologic Perspectives <br /> <br />. <br /> <br />1231H06 <br />f 0.l1 <br />,'t'Ol!> 111l <br />( ,~ <br />'" <br />~" <br />.1111 <br />'" <br />." <br /> <br />EXPLANATION <br /> <br />, <br />'V S'tenumb<-" <br /> <br />- <br />OJ <br />00 <br />';;7 <br /> <br />O'ssolved-sohdSloiJd <br /> <br />M.II,,,,, lo~. pe' y~.' <br />0'0 M."..."... <br />00/ Me.~ <br />0(1'; M'~.m"m <br /> <br />R.~Q~ o! mu~ .~~".' I~ <br /> <br />" 000--100 <br />'V 101_2">0 <br />" 1~'-~OO <br />" G'u'e""'~~OO <br /> <br />o <br />, <br /> <br /> <br />" <br /> <br />,,~ <br />2!> ~ ~~ <br />,.. , <br /> <br />....... <br /> <br /> <br />Figure 44. Malimum. mean. <br />and minimum d,ssolvS<l. <br />solids loads lor 26 stations <br />in the Colorado Aiver basin, <br />1965 to 1983. (Source: Com. <br />plied by J. E. K,rCher from <br />U,S, Geological Survey and <br />U.S. Bureau of Reclamation <br />data) <br /> <br /> <br />WYOMING <br /> <br />. <br />, <br /> <br />B\ g~ <br />yon <br />109081 <br />,~V ." <br />." J,VOll <br />.~ <br />1 ----- <br />18 '\11 0"'" <br />J: O'8V'312028 <br />013 V 0,12 <br />01>&14 0001 003' <br />'.~~ V 1!> Ol~ 002'tf <br />'0'021 2/001 <br />O~, I 01S ..... <br />." I ' (~, 'OM <br />0,0916 . ~J1 I J 1~ O,!06 <br />"H~'~ }-..4"V"6 0.-0 <br />.~V '8. fi'!> <;], 10 COLORADO <br />01~ .1"""OI!1O 13' <br />.~ 1~8l0S1 0,88 .......... <br />],1!>OJ.ol <br />H' <br />I <br />1 <br />1 <br />201891 <br />.1.00 <br />O~9_.__ <br /> <br /> <br /> <br />'COIolUS <br />, <br /> <br />UTAH <br /> <br /> <br /> <br />19r:;j-- <br />VOll <br />lJPl'E1I COt.OIl...OO 0'9 <br />AMRa"'SI" 009 <br />I <br /> <br />, <br /> <br /> <br />NEW <br />MEXICO <br /> <br />ARIZONA <br /> <br />" <br /> <br />.. <br /> <br />...... <br /> <br /> <br />------------- <br /> <br />Se\eral faelors may be influencing the gen- <br />erally decreasing trends in dissol\t~d-solids con- <br />centration ~hown in figure ':6. These fa..:lOrs <br />indude reSef\Olr sforage and operation, <br />dis~ohed-solids control mea'>ure" in Ihe basin, <br />and \'ariations in natural runoff. The dis- <br />soh'ed-solids concentration in rhers generally <br />denease~ wilh increa'eJ streamllo.... on an an- <br />nual ba~is. <br />The period from 1%3 to 1980 represents <br />lhl' most ~ignificant period of re..er\oir filling in <br />thl' history of\\ater development in the Colora- <br />do Ri\er ba...in. The amount of .....ater ,>tored in <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />Flaming Gorge Resen'oir, L.ake Powell, and <br />Lake :\kad collecti\e1y increased from Jess Ihan <br />~O million acre-feet (a<:re-fl) in 1963 to more <br />than 50 million a<:re-ft in 1980. During lhe <br />JX'riod of filling, it is possible Ihat the more <br />dense ....ater (high dis'iohed-solids <:oncen~ <br />trationl moved to the bOllam of the reservoir <br />and the Jess dense watl."r (10\\ dissolved-solids <br />..:oncentration) flo\\ed out of the reservoir. <br />Such a ..ituation \\oulJ l'ause a de<:rease In <br />di,..ol\ed-solids com.cntratiom downslream of <br />thC'resenoir. <br />,\nother po,>sible rea,>on for the trends is <br />l"hanges in irrigation practi..:es. \luch of Ihe <br />farmland that had poor drainage and had <br />excessive dis,ohed ,olids in the soil has been <br />taken out of produ~"tion. In addition, irrigalion <br />prauicC\ have changed significantly during the <br />pa"l 20 years, whkh should de<:rease return <br />110"'" and decrea,>e the dis..ohed ,olid, input 10 <br />'>treams. <br />Many aquifers in lhe region contain large <br />cOI1..:cntratiom of di..,ohed solids but arc con- <br />fined by hundreds of fect of impermeable <br />shall."liI and, therefore. ~.k'ld relatively little sa- <br />line ground waler through springs 10 the <br />streams under natural conditions. However, <br />when the ~'onfining layer,> for lhe saline aquifers <br />are disrupted by mining or drilling, lhe saline <br />ground water can more readily flo" [0 Ihe <br />surface or reach the streams. "Iany saline <br />springs and Ilo....ing ....ell, have been identified <br />in the ba,in. Some of the.sc: flowing wells have <br />been plugged as pan of disso]ved-solids-\.'ontrol <br />proje<:h, such as at \Il'cker Dome, near \feck- <br />er, Co]o., and, therefore, <:ould be causing a <br />df'1.:r\.'a,>ing trend in some areas. The iniliation <br />of other dissol\'ed-solids-control projects dur- <br />ing this period also may cOlllribute to the <br />dc:c1ine in dissohed-'olids concentrations in <br />pans of fhe basin. Each of lhese faclOrs possi- <br />bly ..:ontribute.. to the prl."dominantly decreasing <br />trends in dissol\'Cd-.solids concentrations, but <br />determining the relative imparlance of these <br />major causes will require fun her ,tudy. <br /> <br />. <br /> <br />. <br /> <br />DISSOLVED-SOLIDS CONTROL <br />MEASURES <br /> <br />In 197~, an amendment to the Federal <br />Water Pollution Control A..:t (Public Law <br />92-500) 'el fonh goals that included the reslO+ <br />ration and mainlenance of ""ater quality, Iimi. <br />talion of polluling diluent di~charge~, and <br />e\t'nlua] lero pollution dis..:hargl.". :-';umeri\.'a] <br />criteria ,ubsequemly \\ ere l'~tablished for three <br />station.s t'l\' the Colorado Ri\er Ba~in Salini{\' <br />Control F~rum, adopll."d bv ea..:h of the se\e~ <br />ba..in Sfates. and apNO\cd by the U.S. Em'i- <br />ronmental PrOfe..:tion Agcn..:y. The criteria are: <br />