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<br />. Some developmem and use of nontribllLlry groundwa-
<br />ter is desirable.
<br />
<br />. !'\ontribmary groundw:l.ter mu"t be allocated with spe-
<br />cial care hecause it is essenti:.illy a nonrenewable
<br />resource.
<br />
<br />. An\' nontribm:lIY groundwater ;IU()(.-ation scheme must
<br />recognize that no groundwater i.s completely nontrihu-
<br />lary.
<br />
<br />. \\"Tithdrawa1.s of nOnlributal)' groundwater that affect the
<br />stream syslem should TL"'quire cornpens:llion to the
<br />stream syslem.
<br />
<br />. Administr.uinn in the priority system is a concept ~ener-
<br />ally inapplk;lhle to nOlllrihutary groundwater.
<br />
<br />. The interests of overlying landowners with respecl In
<br />nomributary groundwater should 1)(:" d:uified_
<br />
<br />. Changes in the law should minimize complication and
<br />eXpcn.~.
<br />
<br />The groumlwatt'r legislation n)mmiuec proPO.">t--D lq,tis-
<br />1:1Iion mat resulted in the 19H'i aCI known as Senate Bill 5
<br />(SB 85-5). This act dirt'ned tbe Staw Enginet'r to promul-
<br />g:He rull,s ;md regulatinns for Ihe administration of ground-
<br />water in the Dt.I1\'cr Basin bedrock aquifers. The oftkial
<br />litle of these mle... as adopted is Rules and Rl:'~lilllt/(m5
<br />App(vi'lg Exdtlsin'ly (0 the W-itbdmU'al (1" Grolll/d It"..uer
<br />Ji-v", (he Dau~~Oll, Dew-,<'y' Ampahrx' mul ulrami(',fh\' /lills
<br />Aquifers j'l (hI! Dem-er BasiH. 11ll.:' shun litk. fur tht'se nile"
<br />and regulations is n'e LA!/IH:,r Basi" Rules,
<br />Along widl 7l1e Dem-er Hll:ilrl Rifles. Ihe State Engine\..'r
<br />promulgak.J nle Statewide Sonll1bllfary (im/Oulll'a(er
<br />Rules. TIlese ruks applied to applicllions for claims to
<br />nontribuliHY groundwatt'r outside tht: Denver [lasin. Provi-
<br />sions of the...e rules. indudin1-! the requin.'ment for ohtain-
<br />ing g.cophysical \vell logs. bankin~ of j.;roundwJrer. tilt' 100
<br />ye;1T aquifer life, and the definition... of "wdl field" and
<br />~additi()nal wdl~ also apply to welt.'> taking water from the
<br />Dt.nn~r Basin bedrock aquifers.
<br />SB 8';-) l:slahlished a technic;!1 Jdinition of "nnntrinu-
<br />tHY gmundwater". coined the rerm "nO( n(Jntrihutary~ and
<br />provided for spt:cial lfeatllWnI of the de\'e1opmenl of
<br />!{roundw3ter in these "not nontrihutary" an.';!,>, ;\ontrihu-
<br />tal)' grollnd""-;Iter is now ddined ;1'; ~-that ,l!:roundW3ter-
<br />-the withdrawal of which will not. within 100 rt'ar".
<br />deplele the flow of ;1 n:llural stream. indudin,l.\ a natural
<br />slream as defined in ~ctiom j7-Hl-JOI (2) and j~-91-102
<br />(I) (b), al an ;lnnual r.Jte greater than ()nt'~t\...nth of one
<br />percent of rht: Jnnu:J1 ratt: of withdr;l\ul (from lhe welll."
<br />(CRS r-90-IDj (ID.5}). Thi." is J \"err difficult ....tambrd to
<br />meet. 5B K:;-, also required some of lhe nontrihutary
<br />groundw:ller dt'veloped to IX' relinquisht~d to th.., .....rre;lnl
<br />system.
<br />
<br />Dt.ClOPlfE.\Tm. I1/F REGlL~roR) fR.UfEIlURK FOR DE.\lFR B.ti/.\' ..tQ17n-~
<br />
<br />A fiN step in the ne"J.tion of the Denver B:bin Rules
<br />was a rt'vitow of o\-t'r 3J)OO ~eophysical !tIt!:.... from oil :lnu
<br />R;lS wells :lnd W3.ter wells within the D\...nn:r H:Jsin. U:"ing
<br />;loout 2':;0 of these logs. l'i cross ,-eClioll." were con-
<br />struCled. four in a north-south uirection .lnt! eleven in :m
<br />east-west dirt'l:tiun, TIlt:...e no........ sl.:\lion:- ..'OntlnnL'll lhe
<br />hy[XIth....sis of the State Engint"t.'r that th....re were four
<br />aquifer intervals sep;JT;lIed by signitk:tnt. btcrJlly exlen."i\'e
<br />confining Llyt~rs of cbY"lom' and other fin\'-grJined m:lIeri-
<br />also The ("TO,,-" St"ction" funht'r e.stahli"ht-"f.\ that in some
<br />;lreas, the Dawson and Arap:lhoe aquifers could each 1)(:"
<br />subdivided into an uppt:r ;lnd 100\"l'r hydrogeologic unit.
<br />Additional d:H:1 g;lth....r\...u from the J;v;liLtblc gl.'ophysi\..'al
<br />logs allowed the mapping of lhe top" and b;l~.s of me
<br />indlvidu:ll aqUIfer interval" Sand counts proI..'ided infurma-
<br />tion aoout the net thicknes." of aquift..'r m;\t(.ri;ll.
<br />Literature revil'v.. Jnd field i1l\'t'sligations led to rdined
<br />outnop/sulxrop maps of the Jquifer< and alluviums of
<br />natural stn.'am.".
<br />All of the cross ......ctions ;lnu aquifer maps weft'
<br />reviewed by .1 ~t:ological advisory comminee consiSling of
<br />Stan Rohson of till.." USGS: Curt \\-....I!.s. "'onsultinj.: ,l!:cologist
<br />in the water community: and Rohert Kirkh;un. geologi....t on
<br />the slaff of the Colorado .\-lined Lmd Redamation Board.
<br />111(;,st' independcnt cxpen... Tl~vie\\ed the work of the
<br />CD\X'R staff for consistency and accur:KY.
<br />Knowledge of ;l final component. ...pt...cific yield. was
<br />nen:.ssary to cakiJble how much w:1Ier was acru:Illy :J\"ail-
<br />ahle for withdrawal. Spedfic yield is the Jquifcr propl.'rty
<br />Ihal descrih....s the 3mount of ~rollndw"ter that will drain
<br />by gr:n'ity from a hulk volume of aquifer m:lleriJI. Some
<br />outcrop samples were collected and analyzed for spedlk
<br />yield, Aftt.r lengthy difiCus."ions ht:twt'cn tIlt: CD\,\'R ;Ind
<br />the consulting community. the :lverJ~e .specific yidd..... for
<br />Ihe Denver Basin aquift'rs were dewrm1l1l...d to he 200/u for
<br />the D,tw,.;on. 17't'O for lhe Denver ami the ArJpahol.'. and
<br />1 ';% for tbe Laramie-Fox Hill.. :Iquiti.'rs. Knowing tx)[h Ihe
<br />thk-kne....s of ...:lIuratt>tl :Iquiler mak.rial :md the spedfic
<br />yidd of the a([uift'r. a tbl.'ort'tical volume of drain3ble
<br />wat....r coulu h.... clkl.lbt\..'d for any spl..'dfic parcd of bnd
<br />within tht' Dell\'er Basin. To comply WIth thc IOO-year
<br />aquifer life prunsion. only one pt'rcl.'nt of tht: amount of
<br />water determin"-"f.1 to tx. availahle could hI.' withdr:l\"vn in
<br />;Jny ye:1r. How{..'\-er. !h:u waler Gln hi..' b:mked fr'Om the
<br />date of IS,SI.l;lIKt. of a pemllt or court de..'rl.'"
<br />Tht' final ,,It:fl in ",vJluatm~ the [I.'s()I.lKe was to idt.nrify
<br />the area within t'ach ;lquif('"r that nmt:llOt.d nontrihut::u)"
<br />~rollnd\\.:Her Tht' State mad\.., thai d...lemlin:l!inn by using
<br />.\IOfJrI.O\'\' L\kfJon;lld .llld ~\;lrhallgh. 19H5l. Data files
<br />nmt;lining parameler,> for t::lch aqll1ft:r Wt'r..' ut:ated u"ing
<br />data g:lIh"'I,,'d hr the CD\'\"R :llld the t:.'iGS. .-\ model grid
<br />sy....t(.rn of 12() TOll...... and "",,j ("olumn..... W.I" -.elected, Each
<br />indh-idllal cdl rqJTesenk.d om. ~qllarc mile. and wa....
<br />;lssuOled 10 fl'prt'....enl :l It-g;t1....ect!on of land. \":_due" for the
<br />
<br />1:;-
<br />
<br />Th.., I{.,,:k,. ~1"llnl,lIn :\'''''-",lion ,.f(,<'nl<',Il"h
<br />
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