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

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of fine-grained sedimenb and the o\er.lll geometry of flu-
vial dunnd-depositeu, coar~-gr;llned. water-be;lrin~ inter-
val.. interlaced with (jne-grained Q\'er-hank _"t'dimenl"
Fine-grained sediment.. tend (0 dominale the ...edI01(mtary
sequence; particularly within the Denyer aquifer. wherl'
the net satur.lIed s.lnd thicknt'Ss is ;It mo:-.I 35% of the total
thickness of Ihe unit interval (Roh"Do. 198-). As pointetl
OUI above, thi... ...hale-dominaoct' innl':bl.'''' 10 Iht" t"3st.
away from the sediment source area_
;-':ot only do fine-gr.lint:d :-.edinwnb It'nd to dominat<:
the Basin. hut abo the- lenticul:lr tlu\-ial channd sand lxxl-
ks are interpreted to he se-parated by sh;lle. and therdore
art.' bdievrtl to I~ fXXlrly inll'rt'onneCled hydraulically
(:-;'ielsen. 2001 j, Figure .3 shows gt;.'ophysical logs from a
pair of production wdb in nonhero Douglas County Ihal
includt' nearly all of the Dell\t'r aquifer and tht;' t.'ntire Ara-
paho!;.' aquifer. Shale dearly dominate,> lh... im...ryal covt:re-d
hy Ihese 1\\'0 lo,lo:s. Funhermore. many of the watcr-he-arinj.!:
sand..tone byt'fS vary considerahly in thicknes.s e\'l'n
though these wells are within 100 ft of each otht'f. 111e
limited lateral extent of the waler-tx--aring sandstone byer:-.
trapped within rdati\'ely impermeahle Sh;llL' that is most
evident in the D/;'nver aquif/;'r portion of lbt' logs: this
gt:ometry sll~ests limited hydraulic iOH:rconnt"Clion
throughoUl this interval.

GROU1\TIWATER flOW IN 11-IE DENVER DASI:'oO
AQUIFER SYSTF~\f

Groundwafer flow in thl..' DenV/;'r Il;lsin aquifer system
is complex. j.!:ivt'n the vastness of the aquift'rs and the
complexity of the s/;'dinwmary packaj.!:e. The uSGS has
developt..>u a concept of tht' flow system (Rohson, 19R7)
that, hy necessity, is relatively _~imple in ordn fo form a
foundation for descrihing Iht' dyn;lmics of tht' r!;.'source
and to prt'dict how tht' resource will rl'spond to de\"e1np-
mt'nt Tht' conl:t'ptual modd also (onform.s to the lay/;'rt'd
:lquifer syslem fixed hy statult,'. In Ihis conceptual m(xld.
ground\vater recharges an individual aquift:r by infiltration
of precipit:lIion and/or vertic;ll flow from anotht:r aquifer.
Groundwater disdlargl~.~ from the aquifer by: I) outllow to
connl'Cted surfact' wall'r: 2) flow to an IIndt'rlyin~ :lquifer;
or .3) hy pumpin~.
Unfortunately. tht:R' are few empirical d;lta th;Jt can lx,
1lst.'<I to descritx- WOllndwater l10w conditions in the
aquift'r syslem prior to development however. 1111..' L:-GS
has used 1978 a.s a timt... :-.t:Jning point when devt'1opment
was rdali\'t'1y minor gi\Tn the v3slne-:-..s of the resource.
Groundwater flow in the four prinnpal aquifers using the
1978 benchmark \vas helit'\-ed to haw bet'n gt:nt'rally out-
ward from the southern pan. of the Basin in the- vicinity of
tht' Palmer divide topographic high /Fijot_ I). TI1t" majorllY

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Figure 3. Re5islivit)' logs irom two production wdter we!fs less
lhdn 100ft apart in T6S, R68W in Doug!a~ County show thl;.' greal
lateral variability in thickness oi many 01 the individual waler-
bearing sand~tone layer~_ The dominance of ~hare within the
~quen(e is dearlv ('viden! In the Denver dquifer. Provided by
Glenn Graham, Colorado Division Oi\Volter ~eo;ources.

of no\\' \\':I.~ dirl:"cktJ north toward thl..' 'south platte- Rj\-l'r
(Rohson. lW~-). :\ w-;lter Imdj.tl;'l fIll" the prinCipal aqlllfer>

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