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<br />....
<br />.,.
<br />....
<br />w
<br />
<br />~hallow gwunJ-wulcr "yqenl ha\C'
<br />o('l'n affected by urban land u,c.
<br />t'iut tht''>(' effect.. v, .:rc flll( found in
<br />the dcl'pcr ground water ",cd for
<br />dnnking water.
<br />(;t'Ilt'r:IJly. lun !e\el'llfpt',ti-
<br />ddt'.. <111(1 'ulatilt, organic CHili.
<br />pound.. \\erl' dt.'It'(Il:c1 in gnmnd
<br />\\.II\.'f from !'ohallcl\\ ,,1111\ ial aqui-
<br />fer.. ill urhan area'i, '\1I)sl ;l~!:ri,.-,ul.
<br />lUre (and !X'sIKiJl' u..e! In tll,' ba..in
<br />lll'l'ur" in thl" ColnraJo PJ<llcau
<br />"here gwunJ-w;ucr ..wdic.. \lCf"
<br />Illlt l.olldul'lCJ, The ~..[j,.-,jJc, Ihi.l[
<br />
<br />werc dell'cted in the grounJ water
<br />'>:lmpled in tht' SOLlthern Rocky
<br />~Illuntall\" w,'re pnm;uily herbi-
<br />cide.. u..cd for controlling gra....c...
<br />and \\ced..]n llunagriculturaJ area...
<br />Concentration.. were \el}- !1m lie....
<br />than 0.1 pg/L I I"I'f 1110'-[ llf the [X',,.
<br />IlciJe.. Jt'tC..:h::J. T\\tl ht:rbi..:idc...
<br />brollla,:i1 and pWmt.I{l[l. \\(,Te
<br />detect!."d in urban area, at Cuneen.
<br />Iration, k'"" Ihan lhe LSEPA unn!..-
<br />lIlg-\\ater gUlueline., (L'.S,
<br />EIl\'iwnmenwl Pr\l{t'ct]PIl Agl'ncy.
<br />IYl/{)I.
<br />
<br />Volalilc organic compounds
<br />(vaCS' were delected in ground-
<br />water sample, ;it g.cnl.:rall~ 10"'"
<br />concentratIOns. The ,>IX mo.,t fre-
<br />quetHly detet.ted VOC, were
<br />methyl ral-hutyl ether l.\ITBE).
<br />tetrachloroethenc. chlofl)forrn.
<br />I. J . I-trichloroethane. 1.2.-+-tn-
<br />mcthylhl."nll."lle. and Ji.:hloro-
<br />methane dig. 101. :-.tTBE. a
<br />ga.,nline adJiti\e. wa" delt'ctl'd in
<br />alll."a...1 one wl."Jlm (tlur of lhe rive
<br />mnan are;I' where ,hallo'" ground
<br />waler W<l' .,ampled. In addition.
<br />
<br />RADON CONCENTRATIONS IN UCOL GROUND WATER WERE
<br />GENERALLY HIGHER THAN OTHER AREAS OF THE NATION
<br />
<br />.-.::,
<br />
<br />Radon concentrations in alluvial aquifers of the UCOL are among the highest ()f all NA WQA ground-water
<br />samples natinll\\.-'ide (5.J. Ryker. USGS. written COlllmun., 1999). Radon is a naturally ol..'curring. colorless. ooor-
<br />Ie....._ radioactive gas derived from the decay of uranium. Radon has been identified as a human carcinogen and
<br />can elller a building from seepage (If air lhrough din Ihxm;. cracks in concrete floors or walls, floor drains, or
<br />through the use of water supplied from wells. A grealer risk of expo,",urc to radon exist1> in urban areas due to the
<br />prevalence of enclosed structures. such as baselTlen~. which can lrap radon gas.
<br />Though the USEPA does nol currently (2000) regulate radon in drinking ",.ater. there j.. a proposed maximum
<br />contaminam level (MCL) of 300 picocuries per liter (pCi/L) for radon in drinking waler (U.S. Environmental
<br />Protection Agency. 1999). Radon concentralions were greater than the proposed :"ICL for all wells sampled in
<br />the SllUthern Rocky ,'Iountains. Higher radon c:oncenlrations were measured in the Winter Park/Fraser and
<br />Silverthorne arcas. Igneous and metamorphic rocks. which can contain uranium-bearing minerals. are common
<br />rock ty!X's in these area,~,
<br />
<br />----.,.-,
<br />--"""-':--' '
<br />
<br />!-t...-.
<br />".,--...!
<br />"'V'
<br />~. ,
<br />-,;<..
<br />,1,-'
<br />
<br />'{~':'-.c':
<br />
<br />.
<br />,
<br />,
<br />.,.
<br />
<br />
<br />,
<br />
<br />~'
<br />
<br />A
<br />.
<br />.
<br />.
<br />:i> j
<br />"'\:- ~
<br />
<br />,
<br />
<br />~.---
<br />
<br />-'
<br />
<br />
<br />-.
<br />.
<br />~
<br />
<br />[V~----O--
<br />
<br />"-
<br />.....1 EXPLANATION ~
<br />
<br />Ranking of ground-waler radtln concentrations Study Units' radon concentrations ----f
<br />relative to all NAWQA ground-water studies in ground water. in plcocuries
<br />(dala from multipla walls in lndicatlld arnal per liter (pCIILI
<br />
<br />. Grealer than the 95th percentile
<br />. Bety,'een the 90th and 95th percentile
<br />. Between the 75th and 90th percentile
<br />
<br />,I---~'-
<br />" '
<br />., .\
<br />, '\J3,/
<br />';:
<br />~
<br />
<br />. 1,000 in ..t 181'15125 percent of samples
<br />D 600 in at least 25 percent of samples
<br />~ 300 in alleast25 percent of samples
<br />e 300 In fewer than 25 percent of samples
<br />
<br />:-'Iajor Fillding~ 9
<br />
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