PUB00006

• Year: 2005
• Title: Colorado's Historic Water Projects
• CWCB Section: Administration
• Author: Applegate Group, Inc
• Description: A calender with pictures and descriptions of historic water projects.
• Publications - Doc Type: Historical

Groundwater Residence Time and Recharge Temperature Estimates of the
Denver and Arapahoe Aquifers, Denver Basin, Colorado'

MILOS M. NOVOTNY'
WILLIAM E. SANFORD'

1. ,I.\anuscripl rN:l"ivro Augu~1 2; ACC('pI...d August 12. 2004_
2. 55. Pap..d<lpUl~ & As-.oci.ltl.... 1877 Br(),]<h~.l~ 5703, Bou!dt...., co 8tHOl
3. Department oi Geoscien(~. Colorado St.lle Uni\'I'"ilV. Fot1 Colltns, CO 8052 3

ABSTRACT

Grouolhvater S-;.unples w("re collecteo from :-.Lx ~rollml\\"att:r production wells in 11ll' Denver and Ara-
pahOt:." aquifers of the f)cOH'r Basin along ;! tran~ect from neaf the suspcned n:charge arca in the south
to urb;in centers in the central hasin. lksidencc limes were c....tim:ltt:~d ,,:ith He using an empirical factor
(0 correct fOf dilution. Recharge temp~:r;.lture was estimatl..'d ".-jlh ,I modd th:H rdales nmcentr.lIions of
dissol\"cd atmospheric noble gases (Ne. Ar. and Kr) in the groundwater samples to lemperaturc. cJey:t~
tion and an exo:ss-air component. Residence time estimates r:lIlgc from 8.000 years near the outcrops of
the aquifers to greater than 30.000 years near the center of the hasin. 111e recharge temperature t"stimalt"
of [he youngest water is similar lO mo(.krn mean-annual temperature while waters from Ihe centr.ll basin
hayc signillcanlly cooler recharge temperatures. The relationship of recharge temperature and residence
time to ~cnl'ral climate rl.'cords sug,.l.teSls possible mixing of youngl'r Hol(Kl'ne waters in two of the cen-
tral basin samples.

INTROOUCTION ........... .......161
Background.... ....... ...... .162
Groundwater Flow and FnvironmenTalTracer~.. .162
Camon_14Re-sidencl'Timl'.. ...... ..162
Recharge TemperdTure . . . . . . . . . .163
METHODS.... ..... ........ ..163
Sampling..... ........ ... ...... ...163
Caroon-14 Activity DiluTion .1nd DeterminaTion
oiResidenceTime ....... ........ ..163

...... .164
.. ..164
....... .164
.. ....... .165
...........166
.............. .166
............. .166

Modd of Recharge Temperature
RESULTS AND DISCUSSION

ResidenceTimes ............
E~limat('d Palrolemper<llUres
SU...IMARY .....
ACKNOWLEDGMENTS. .
REFERENCES .........

I:"tiTRODliCllO:\"

TIle populaTion of Color;IJo's Front Ran~e ha.. J.{ruwn
tn::menJously over Ihe Iasl 50 yt:'".l.~ and f.:ro\\lh is prcdkk-tl
to continue at a similar fak' on'r TIll." nl'X1 20 years; ho\\"en~r.
lht' volume of us;lhlc W;Il('f will r('maln rdatively fLxl.-J. ~Llr'
faCt.' \v:ller b alfl'aJy fully allocated. fequirmg nt'w ,lL'mand
lO lx. partially sati"fit:d hy exploiting the txoJnx-k aquife~ of
the Dem'er B;ls;n. On:rexploi(;ltion of lb:p woundw;ucr in
o;llniLu ba:.lI1.o; ha" It'd to nuny dd(.'lcriou.. dt~L" indudlnf.:
lowenng of the potenliomdril" .:;urfacc. bnd suh"llknce and
degr.l.dation of water qU;IIif':.- lCu.""-uuiu, 101ll\.

-,nt'.II01mtaw C.~,[('!oll'f. Vol It ~" .1 1(.)".-10h,:. llHH. p \(1T-JiJ-

:'\um....ric;ll woumlwaT...'r m(xkb of Lhe Denver Basin
a4u1kr"> lu\e ht,t'n and are culTt.'ntly hl'ing crC"'.ItL"ti and 1ll'x1-
ifieti. The:-t' modds Gin tx~ USl.'1.1 10 predll1 the dft.'1.b of
incfl';l.sl'd wilhdrawals ~ind to eslinull.' till' total amoUnT of
W;Jtl.'r a\'aibhk, \1.l1l\" ha..in-,,,,--":ak moJds are calibratL-d to
prl..,(..nt-day roto:rniomdric surf:tce>, and fl.'l'harj.(l.' to (he
,lqllifl.'~ b nk'rdy e.stJll1atl.'d Datl collel1l'J providing insiglu
Tn lhe reskk-ncl.' time ot walef ;It various !rx<ltions can weatly
deue;lSl..' t1rKcn.:unlil.'" in the wounJw;ller m(>l.ld...,
In Ibis r;lrer. ;Jprarenl fl'"idl.'nct' lim...." ot w;ltl.'r S3m-
rJo:J from "t'n'r;11 location" witbin the Arap;lno.... and Dl.'n-
n'r ~14uift'r" of lbe fknn'r Basin arc pu:.......nTed along with

16\

The 1I,,,.Io:\, \1'>lJnlam '\"''"x'Mhonof(......,lt>j;:;o;t,