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<br /> 1>OIIocN<B&i<..-GUd'> iu<w~SIlej lu:t>an~)
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<br /> N'TRITE .>..I.".lO!'j'A TOTAL OlSSOl VEO 0'''><>
<br /> "lUSt-lITR.AtE PHOSPHQAUS PWJSPHOOus PHOSPHATE
<br />
<br />Figure 7. Concentrations of nitrile plus nitrate and total phosphorus were
<br />greater at sites with urban development (Gore GreeK and East River) than at
<br />the reference slte (Colorado River below Baker GUlCh). SItes shown In order of
<br />Increasing urban development. A log scale IS used due fa the large range of
<br />concentrations,
<br />
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<br />3: . 5
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<br />1.-.1,""""",",,01 "'81
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<br />(ultl4n
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<br />
<br />Figure 8. Algal biovolume (the amount or algae) was greater al Gore Creek.
<br />which also has grealer urban development. The percentage of mayflies.
<br />stonellies. and caddlsfltes decreased. and the percentage ot midges (indlcallve
<br />of more degraded water Quality) increased with urban development. Sites shown
<br />In order Of Increasing urban development.
<br />
<br />Nll;roo,~....r.:- East Rrver .
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<br />OCT '""" A,P" JULY OCT "A" AP" .lUl Y OCT J"'; ItP<l .J\Jl Y OCT
<br />"-HER YEAR ,_ .......ni'l n:.... '1lS~ ......TER YEAR !i'9B
<br />
<br />Figure 9. Nutfient conCentrallons were greatest during the lale winter low.flow
<br />periOd pnor to peak snowmelt runoff. This pattern was similar lor total phOSPhOrus
<br />at East River and lor nitrite plus Mrale and IOlal phOSphorus at Gore Creek,
<br />
<br />(maytlies. sllIndlic". and caddis~
<br />tlie~) wa~ grl'ater at sill's wilh less
<br />urhan inlluC'Il....C ICulorado River
<br />helow Baler Gulch. Ilg. 81. The
<br />pen.:entage 01 nudges (insccts gen-
<br />l'rall~ lok'rant of Pllllution I
<br />increased with in..:rc<lsin!; urban
<br />inlluelh:c (Ll'>( RivC'r and Gore
<br />Crcd "lies. tlg. SJ. Even though
<br />Ihe pen.:erHage ll! midges \\'3:<'
<br />greater al Gl)re In:ck. the in\'erte-
<br />hra!e stalUs of Gore Creek wa.. Ie...s
<br />degraded Ihan mher urban siles in
<br />thl' .'\J:\ WQ.-\ Program I p. lh
<br />
<br />~lllril'lIll'onl.l'lIlratillll.. \\ere
<br />J.:l'IIl'rull~ larg(',..,l dllrinJ.: winter.
<br />C{lr'1~'ent(;ltillm of nitrite plus
<br />nitrall' and dj-.,\oh ed and t{ltal
<br />pl1n~phnrus \\cre ,t.:n:ate\t during
<br />the late \\ Inter low-llow penud
<br />pnor !l) "ntmmell run<Jt'f (Ilg. 9).
<br />With the on.....1 lll' ...nowmelt runoff.
<br />nutrie11l <.'\llll.entratillll... were
<br />diluled. Algal uptake of nutrients
<br />durin!; warm w..'alhlor duly.
<br />OClober) probahly 100\er eonn:n-
<br />tr<1[1(,n... during tIll' Sllll1ll11'r. Wilh
<br />rl'duCI'J dllutitln and dimini...hed
<br />algal uplal...c. nutrient concentra.
<br />tmn.. inl.rea~l' again during the win-
<br />tl'r low-l1{m p,,'nod.
<br />
<br />Gruund.\\.lI{'r sludit''- ill\('sli.
<br />gall'd till' ell'el.l.... uf urhan land
<br />U\l' 011 walt'r ill ,-dt,t'tt'd alhl\'ial
<br />aquifers. ..\lthl'ugh many commu-
<br />nille... in the L'COL rely on surface
<br />water a\ their primary ,>(lur..:C' of
<br />drinking \\ ater. a rev. mount;lin
<br />[{lWlb and many tllllusand... of
<br />Individual h1l11lC.. in the Southt.'nl
<br />RlX'l...~ \hlllntall1~ U..t' ground
<br />waler a.. their primary Water
<br />soun.:c. Effech of urban land ust'
<br />c:.In ne in..hc:Hed by de\att'd con-
<br />...et1lration.. llf nnrate. detections of
<br />..ynthellc organic COlllpl)unds IJX''''-
<br />ti..-idc.. :.Ind \"QC\J. and bacteria.
<br />
<br />\1aJl'f Finding.. 7
<br />
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