Post on 16-Jul-2018
Introduction 5
Geologic Setting
The geologic units that contain aquifers for which water-quality characteristics are presented are described in this section from oldest to youngest. The oldest geologic units in the study area are the Precam-brian crystalline (metamorphic and igneous) rocks (fig. 2), which form a basement under the Paleozoic, Mesozoic, and Cenozoic rocks and sediments. The Precambrian rocks are exposed in the central core of the Black Hills. These Precambrian rocks range in age from 1.7 to about 2.5 billion years, and were eroded to a gentle undulating plain by the beginning of the Pale-ozoic Era (Gries, 1996). The Precambrian rocks are highly variable, but are composed mostly of metasedi-ments, such as schists and graywackes. The Paleozoic and Mesozoic rocks were deposited as nearly hori-zontal beds. Subsequent uplift during the Laramide orogeny and related erosion exposed the Precambrian rocks in the central core of the Black Hills with the Paleozoic and Mesozoic sedimentary rocks exposed in roughly concentric rings around the core. Deformation during the Laramide orogeny contributed to the numerous fractures, folds, and other structural features present throughout the Black Hills. Tertiary intrusive activity also contributed to rock fracturing in the northern Black Hills where numerous intrusions exist.
Surrounding the crystalline core is a layered series of sedimentary rocks including limestones, sand-stones, and shales. The distribution of hydrogeologic units in the Black Hills area is shown in figure 3. The bedrock sedimentary units typically dip away from the uplifted Black Hills at angles that can approach or exceed 15 to 20 degrees near the outcrops, and decrease with distance from the uplift to less than 1 degree (Carter and Redden, 1999a, 1999b, 1999c, 1999d, 1999e) (fig. 4).
The oldest sedimentary unit in the study area is the Cambrian- and Ordovician-age Deadwood Forma-tion, which is composed primarily of brown to light-gray glauconitic sandstone, shale, limestone, and local basal conglomerate (Strobel and others, 1999). These sediments were deposited on the generally horizontal plain of Precambrian rocks in a coastal- to near-shore environment (Gries, 1975). The thickness of the Deadwood Formation increases from south to north in the study area and ranges from 0 to 500 feet (Carter and Redden, 1999e). In the northern and central Black Hills, the Deadwood Formation is disconformably overlain by Ordovician-age rocks that include the Whitewood and Winnipeg Formations. The Winnipeg Formation is absent in the southern Black Hills, and the Whitewood Formation has eroded to the south and is
not present south of the approximate latitude of Nemo (DeWitt and others, 1986). In the southern Black Hills, the Deadwood Formation is unconformably overlain by the Devonian- and Mississippian-age Englewood Formation because of the absence of the Ordovician-age sequence. The Englewood Formation is overlain by the Madison Limestone.
The Mississippian-age Madison Limestone, deposited as a marine carbonate, is a massive, gray to buff limestone that is locally dolomitic (Strobel and others, 1999). The thickness of the Madison Limestone increases from south to north in the study area and ranges from almost zero in the southeast corner of the study area (Rahn, 1985) to 1,000 feet east of Belle Fourche (Carter and Redden, 1999d). The Madison Limestone was exposed above land surface for approx-imately 50 million years. During this period, signifi-cant erosion, soil development, and karstification occurred (Gries, 1996). Numerous caves and fractures occur within the upper part of the formation (Peter, 1985). Because the Madison Limestone was exposed to erosion and karstification for millions of years, the formation is unconformably overlain by the Minnelusa Formation.
The Pennsylvanian- and Permian-age Minnelusa Formation consists mostly of yellow to red cross-stratified sandstone, limestone, dolomite, and shale (Strobel and others, 1999). In addition to sandstone and dolomite, the lower part of the formation consists of shale and anhydrite (DeWitt and others, 1986). The upper part of the Minnelusa Formation also may contain anhydrite, which generally has been removed by dissolution at or near the outcrop areas, forming collapse features filled with breccia (Bowles and Braddock, 1963). The thickness of the Minnelusa Formation increases from north to south and ranges from 375 feet near Belle Fourche to 1,175 feet near Edgemont in the study area (Carter and Redden, 1999c). On the southwest side of the study area, there is a considerable increase in thickness of clastic units as well as a thick section of anhydrite. In the southern Black Hills, the upper part of the Minnelusa Formation thins due to leaching of anhydrite. The Minnelusa Formation is disconformably overlain by the Permian-age Opeche Shale, which is overlain by the Minnekahta Limestone.
The Permian-age Minnekahta Limestone is a fine-grained, purple to gray laminated limestone with thicknesses ranging from 25 to 65 feet in the study area (Strobel and others, 1999). The Minnekahta Limestone is overlain by the Triassic- and Permian-age Spearfish Formation.
6 Water-Quality Characteristics in the Black Hills Area, South Dakota
Fig
ure
2.
Str
atig
raph
ic s
ectio
n fo
r th
e B
lack
Hill
s.
ST
RA
TIG
RA
PH
IC U
NIT
DE
SC
RIP
TIO
NT
HIC
KN
ES
SIN
FE
ET
AB
BR
EV
IAT
ION
FO
RS
TR
AT
IGR
AP
HIC
INT
ER
VA
L
SY
ST
EM
ER
AT
HE
M
QU
AT
ER
NA
RY
& T
ER
TIA
RY
(?)
UN
DIF
FE
RE
NT
IAT
ED
SA
ND
S A
ND
GR
AV
ELS
0-50
San
d, g
rave
l, an
d bo
ulde
rs
1,20
0-2,
700
Ligh
t col
ored
cla
ys w
ith s
ands
tone
cha
nnel
filli
ngs
and
loca
l lim
esto
ne le
nses
.
WH
ITE
RIV
ER
GR
OU
PT
w
TE
RT
IAR
Y
QT
u
Prin
cipa
l hor
izon
of l
imes
tone
lens
es g
ivin
g te
epee
but
tes.
Dar
k-gr
ay s
hale
con
tain
ing
scat
tere
d co
ncre
tions
.
Wid
ely
scat
tere
d lim
esto
ne m
asse
s, g
ivin
g sm
all t
eepe
e bu
ttes.
Bla
ck fi
ssile
sha
le w
ith c
oncr
etio
ns.
PIE
RR
E S
HA
LE
NIO
BR
AR
A F
OR
MA
TIO
N1 8
0-30
0Im
pure
cha
lk a
nd c
alca
reou
s sh
ale.
CA
RLI
LE S
HA
LET
urne
r S
andy
Mem
ber
Wal
l Cre
ek M
embe
r
1 350
-750
Ligh
t-gr
ay s
hale
with
num
erou
s la
rge
conc
retio
ns a
nd s
andy
laye
rs.
Dar
k-gr
ay s
hale
GRANEROS GROUP
GR
EE
NH
OR
N F
OR
MA
TIO
N
Kps
225-
380
Impu
re s
labb
y lim
esto
ne.
Wea
ther
s bu
ff.
Dar
k-gr
ay c
alca
reou
s sh
ale,
with
thin
Orm
an L
ake
limes
tone
at b
ase.
BE
LLE
FO
UR
CH
E S
HA
LE
MO
WR
Y S
HA
LE
MU
DD
YS
AN
DS
TO
NE
NE
WC
AS
TLE
SA
ND
ST
ON
E
SK
ULL
CR
EE
K S
HA
LE
150-
850
Gra
y sh
ale
with
sca
ttere
d lim
esto
ne c
oncr
etio
ns.
Cla
y sp
ur b
ento
nite
at b
ase.
125-
230
0-15
0
Ligh
t-gr
ay s
ilice
ous
shal
e. F
ish
scal
es a
nd th
in la
yers
of b
ento
nite
.
Bro
wn
to li
ght y
ello
w a
nd w
hite
san
dsto
ne.
150-
270
Dar
k gr
ay to
bla
ck s
ilice
ous
shal
e.
CR
ET
AC
EO
US
FA
LL R
IVE
R F
OR
MA
TIO
N
LAKOTAFM
INYAN KARAGROUP
Fus
on S
hale
Min
new
aste
Lim
esto
neC
hils
on M
embe
r
10-2
00M
assi
ve to
sla
bby
sand
ston
e.
Coa
rse
gray
to b
uff c
ross
-bed
ded
cong
lom
erat
ic s
ands
tone
, int
erbe
dded
with
buf
f, re
d,
and
gra
y cl
ay, e
spec
ially
tow
ard
top.
Loc
al fi
ne-g
rain
ed li
mes
tone
.
10-1
90
0-25
25-4
85
0-22
0
0-22
5
Ligh
t-gr
ay c
lays
tone
and
sha
le.
Thi
n sa
ndst
one.
Mas
sive
fine
-gra
ined
san
dsto
ne.
250-
450
0-45
Gre
enis
h-gr
ay s
hale
, thi
n lim
esto
ne le
nses
.
Gla
ucon
ltic
sand
ston
e; r
ed s
ands
tone
nea
r m
iddl
e.
Red
silt
ston
e, g
ypsu
m, a
nd li
mes
tone
.
MO
RR
ISO
N F
OR
MA
TIO
N
UN
KP
AP
A S
SR
edw
ater
Mem
ber
Lak
Mem
ber
Hul
ett M
embe
rS
tock
ade
Bea
ver
Mem
.C
anyo
n S
pr M
embe
r
SU
ND
AN
CE
FO
RM
AT
ION
GY
PS
UM
SP
RIN
G F
OR
MA
TIO
N
Kik Ju
JUR
AS
SIC
Goo
se E
gg E
quiv
alen
tS
PE
AR
FIS
H F
OR
MA
TIO
NT
Ps
RT
RIA
SS
IC
MIN
NE
KA
HT
A L
IME
ST
ON
EO
PE
CH
E S
HA
LEP
oP
mk
375-
800
1 25-
65
Red
san
dy s
hale
, sof
t red
san
dsto
ne a
nd s
iltst
one
with
gyp
sum
and
thin
lim
esto
ne la
yers
.
Gyp
sum
loca
lly n
ear
the
base
.
Thi
n to
med
ium
-bed
ded
finel
y-cr
ysta
lline
, pur
plis
h gr
ay la
min
ated
lim
esto
ne.
Red
sha
le a
nd s
ands
tone
.1 2
5-15
0
1 375
-1,1
75
1 250
-1,0
00
30-6
01 0
-235
1 0-1
50
1 0-5
00
Yel
low
to r
ed c
ross
-bed
ded
sand
ston
e, li
mes
tone
, and
anh
ydrit
e lo
cally
at t
op.
Red
sha
le w
ith in
terb
edde
d lim
esto
ne a
nd s
ands
tone
at b
ase.
Mas
sive
ligh
t-co
lore
d lim
esto
ne.
Dol
omite
in p
art.
Cav
erno
us in
upp
er p
art.
Pin
k to
buf
f lim
esto
ne.
Sha
le lo
cally
at b
ase.
Buf
f dol
omite
and
lim
esto
ne.
Gre
en s
hale
with
silt
ston
e.M
assi
ve to
thin
-bed
ded
brow
n to
ligh
t-gr
ay s
ands
tone
. G
reen
ish
glau
coni
tic s
hale
f
lagg
y do
lom
ite a
nd fl
at-p
ebbl
e lim
esto
ne c
ongl
omer
ate.
San
dsto
ne, w
ith
con
glom
erat
eloc
ally
at t
he b
ase.
Sch
ist,
slat
e, q
uart
zite
, and
ark
osic
grit
. In
trud
ed b
y di
orite
, met
amor
phos
ed
to
amph
ibol
ite, a
nd b
y gr
anite
and
peg
mat
ite.
PE
RM
IAN
PE
NN
SY
LVA
NIA
N
MIS
SIS
SIP
PIA
N
P P
mM
INN
ELU
SA
FO
RM
AT
ION
MA
DIS
ON
(P
AH
AS
AP
A)
LIM
ES
TO
NE
EN
GLE
WO
OD
FO
RM
AT
ION
MD
me
Ou
DE
VO
NIA
NW
HIT
EW
OO
D (
RE
D R
IVE
R)
FO
RM
AT
ION
WIN
NIP
EG
FO
RM
AT
ION
DE
AD
WO
OD
FO
RM
AT
ION
UN
DIF
FE
RE
NT
IAT
ED
ME
TA
MO
RP
HIC
AN
D IG
NE
OU
S R
OC
KS
OC
d
pCu
OR
DO
VIC
IAN
CA
MB
RIA
N
PR
EC
AM
BR
IAN
PA
LEO
ZO
IC
ME
SO
ZO
IC
CE
NO
ZO
IC
Mod
ified
from
inf
orm
atio
n fu
rnis
hed
by th
e D
epar
tmen
t of G
eolo
gy a
nd G
eolo
gica
l Eng
inee
ring,
Sou
th D
akot
a S
choo
l of M
ines
and
Tec
hnol
ogy
(writ
ten
com
mun
., Ja
nuar
y 19
94)
0-30
0In
clud
es r
hyol
ite, l
atite
, tra
chyt
e, a
nd p
hono
lite.
IN
TR
US
IVE
IGN
EO
US
RO
CK
ST
ui--
1 M
odifi
ed b
ased
on
drill
-hol
e da
ta
Inte
rbed
ded
sand
ston
e, li
mes
tone
, dol
omite
, sha
le, a
nd a
nhyd
rite.
Introduction 7
CascadeSprings
Rochford
Whitewood
Spearfish
Maurice
Savoy
SaintOnge
DEADWOOD
Lead
Galena
Nemo
CentralCity
BELLE FOURCHE Minnesela
Newell
Vale
Fruitdale Nisland
STURGIS
Blackhawk
Piedmont
Tilford
Box Elder
RAPID CITY
Hill City
Hermosa
CUSTER
HOT SPRINGS
Edgemont
Roubaix
Keystone
Hayward
Fairburn
Buffalo Gap
Pringle
Wild
Inlet
Ditch
NF
orkR
apidC
r
Belle FourcheReservoir
FOURCHE
Victoria
Spring
RapidIrishman
Hawthorn
Gulch
Canyon
South
Grace
Cool i d ge
Cotton wood
AngosturaReservoir
Iron
Creek
Lit
tle
Castle
Cr
N Fork Castle Cr
Rhoads Fork
Can
yon
Red
BearG
ulch
Creek
Crow
SheridanLake
StockadeLake
DeerfieldReservoir
PactolaReservoir
Indian Cr
Horse
Creek
OwlCreek
BELLE
RIVER
REDWATER R I VE
RC
reek
Spea
rfis
h
Whi
tewoo
d
Cre
ek
Creek
Bear
Butte
Elk
Elk
Creek
Creek
Creek
Boxelder
Rapid
Creek
Creek
Creek
Creek
Creek
Creek
Creek
Cre
ek
S. Fork
S. Fork Rapid Cr
Battle
French
Beaver
Creek
Creek
Cre
ek
Creek
FallR
Hat
Cre
ek
Creek
Horsehead
CHEYENNE
RIVER
Cot
tonw
ood
CreekHay
Spokane
Lame
Johnny
Bea
ver
Cre
ek
Robison
Gulch
Gulch
Castle
Cas
tle
Bear
Reno
Little
StrawberryCreek
Gulch
Hig
gins
Creek
C reek
Cr
Cr
Cr
CrE
ast
Creek
Bot
tom
False
Spea
rfis
h
Squaw
Annie
Spearfish
North
Canal
Canal
IronDraw
Angostura
Canal
Cox Lake
MurrayDitch
RedwaterCanal
Gulch
SheridanLakeTributary
CitySprings
Wind CaveNational Park
CUSTER
STATE
PARK
WindCave
HarneyPeakx
BUTTE CO
LAWRENCE CO MEADE CO
PENNINGTON CO
CUSTER CO
FALL RIVER CO
WY
OM
ING
SO
UT
H
DA
KO
TA
LIM
ES
TO
NE
PL
AT
EA
UQTac
Tw
Tui
Kps
Ju
TRPs
MDme
Kik
Pmk
Po
Ou
PPm
OCd
pCu
A
A'
Figure 3. Distribution of hydrogeologic units in the Black Hills area (modified from Strobel and others, 1999).
0 10 20
0 10 20 MILES
KILOMETERS
EXPLANATION
Alluvium and colluvium, undifferentiaed
Unconsolidatedunits
White River aquifer
Minnekahta aquifer
Minnelusa aquifer
Madison aquifer
Deadwood aquifer
Inyan Kara aquifer
Tertiary intrusiveunits
Spearfish confiningunit
Opeche confiningunit
Cretaceous-sequence
confining unit
Jurassic-sequencesemiconfining unit
Ordovician-sequencesemiconfining unit
Precambrian igneousand
metamorphic units
White River Group
Undifferentiated intrusive igneous rocks
Pierre Shale to Skull Creek Shale, undifferentiated
Inyan Kara Group
Morrison Formation to Gypsum Spring Formation, undifferentiated
Spearfish Formation
Minnekahta Limestone
Opeche Shale
Minnelusa Formation
Madison (Pahasapa) Limestone and Englewood Formation
Whitewood Formation and Winnipeg Formation
Deadwood Formation
Undifferentiated metamorphic and igneous rocks
StratigraphicUnits Map Units
HydrogeologicUnits
A A' LINE OF GEOLOGIC SECTION
FAULT--Dashed where approximated. Bar and ball on downthrown side.
ANTICLINE--Showing trace of axial plane and direction of plunge. Dashed where approximated.
SYNCLINE--Showing trace of axial plane and direction of plunge. Dashed where approximated.
MONOCLINE--Showing trace of axial plane. Dashed where approximated.
DOME--Symbol size approximately pro- portional to size of dome. Dome asymmetry indicated by arrow length.
Base modified from U.S. Geological Survey digital data, 1:100,000Rapid City, Office of City Engineer map, 1:18,000, 1996Universal Transverse Mercator projection, zone 13
104o 45' 103o30'
15' 103o
30'
44o45'
15'
44o
45'
30'
43o15'
8 Water-Quality Characteristics in the Black Hills Area, South Dakota
SE
ALE
VE
L
1,00
0
2,00
0
3,00
0
4,00
0
5,00
0
6,00
0
SE
ALE
VE
L
1,00
0
2,00
0
3,00
0
4,00
0
5,00
0
6,00
0
7,00
0F
EE
TA
A'
7,00
0F
EE
T
MD
me
MD
me
Kps
JuK
ik
PP
m
PP
m
OC
d
OC
dP
mk
Po
QTa
cQ
Tac
Rapid CreekRapid Creek
South Fork Castle Creek
Highway 385
Rapid Creek
Highway 44Rapid Creek
Rapid City
Rapid Creek
21
0
21
04
2
24
68
10M
ILE
S
86
10K
ILO
ME
TE
RS
VE
RT
ICA
L E
XA
GG
ER
ATIO
N X
5
T P
sR
Fig
ure
4.
Geo
logi
c cr
oss
sect
ion
A-A
' (Lo
catio
n of
sec
tion
is s
how
n in
figu
re 3
. A
bbre
viat
ions
for
stra
tigra
phic
inte
rval
s ar
e ex
plai
ned
in fi
gure
2.)
.
Mod
ified
from
Str
obel
and
oth
ers,
199
9
SOUTH DAKOTA
WYOMING
pCu
pCu
Introduction 9
The Permian- and Triassic-age Spearfish Forma-tion consists of red, silty shale interbedded with friable, red sandstone and siltstone, and sparse limestone layers (Strobel and others, 1999). The lower portion of the Spearfish Formation contains massive gypsum (Robinson and others, 1964). The thickness of the Spearfish Formation ranges from 375 to 800 feet (Gries and Martin, 1985).
Jurassic-age units consisting of shale and sand-stone with some limestone and gypsum overlie the Spearfish Formation and include the Sundance and Morrison Formations. The Sundance Formation con-sists of reddish-gray to light-gray siltstone, sandstone, limestone, and glauconitic sandstone and shale (DeWitt and others, 1989) and is 250 to 450 feet thick in the study area (Strobel and others, 1999). The Morrison Formation is a light-gray siliceous claystone and shale (DeWitt and others, 1989) with a thickness that ranges from 0 to 220 feet (Strobel and others, 1999).
The Cretaceous-age Inyan Kara Group consists of the Lakota Formation and overlying Fall River Formation. The Lakota Formation consists of the Chilson, Minnewaste Limestone, and Fuson Shale members. The Lakota Formation consists of yellow, brown, and reddish-brown massive to thin-bedded sandstone, pebble conglomerate, siltstone, and clay-stone of fluvial origin (Gott and others, 1974); lenses of limestone and coal are present locally. The Fall River Formation is a brown to reddish-brown, fine-grained sandstone, thin bedded at the top and massive at the bottom (Strobel and others, 1999). The thickness of the Inyan Kara Group ranges from 135 to 900 feet in the study area (Carter and Redden, 1999a).
The Cretaceous-age Graneros Group includes the Skull Creek Shale, Newcastle Sandstone, Mowry Shale, and Belle Fourche Shale. The Skull Creek Shale is a dark gray to black siliceous shale and is 150 to 270 feet thick (DeWitt and others, 1989). The Newcastle Sandstone is 0 to 100 feet thick and is a gray to light-brown sandstone and siltstone that contains beds of bentonite and lignite (DeWitt and others, 1989). The Mowry Shale consists of light-gray sili-ceous shale with thin bentonite layers and is 125 to 230 feet thick (DeWitt and others, 1989). The Belle Fourche Shale is a dark-gray bentonitic shale that con-tains minor limestone lenses and large concretions and is 150 to 850 feet thick (DeWitt and others, 1989).
The Cretaceous-age Pierre Shale is a dark-gray to black shale containing minor limestone lenses and concretions. The thickness of the Pierre Shale ranges from 1,200 to 2,700 feet (Strobel and others, 1999).
For purposes of this report, alluvial deposits refer to Quaternary-age alluvium, gravel deposits, and windblown deposits and Tertiary-age gravel deposits. Generally, the thickness of these deposits ranges from 0 to 50 feet.
Hydrologic Setting
The hydrologic setting of the Black Hills area is schematically illustrated in figure 5. The major aquifers in the Black Hills area are the Deadwood, Madison, Minnelusa, Minnekahta, and Inyan Kara aquifers. Aquifers in the Precambrian rocks also were considered as a major aquifer in this report because numerous wells are completed in this unit. In some local areas, wells are completed in strata that generally are considered semiconfining or confining units. These local water-bearing strata are referred to as minor aquifers in this report. This section describes the hydrologic setting for the major and minor aquifers considered in this report.
Major Aquifers
The Precambrian basement rocks generally have low permeability and form the lower confining unit for the series of sedimentary aquifers in the Black Hills area. Localized aquifers occur in Precambrian rocks at many locations in the central core of the Black Hills, where enhanced secondary permeability results from weathering and fracturing. These localized aquifers are referred to as the Precambrian aquifers in this report. In the Precambrian aquifers, water-table (unconfined) conditions generally prevail and land-surface topog-raphy can strongly control ground-water flow direc-tions. Many wells completed in the Precambrian aquifers are located along stream channels.
Many of the sedimentary units contain aquifers, both within and beyond the study area. Within the Paleozoic rock interval, aquifers in the Deadwood Formation, Madison Limestone, Minnelusa Formation, and Minnekahta Limestone are used extensively. These aquifers are collectively confined by the under-lying Precambrian rocks and the overlying Spearfish Formation. Individually, these aquifers are separated by minor confining layers or by relatively impermeable layers within the individual units. In general, ground-water flow in these aquifers is radially outward from the central core of the Black Hills. Although the lateral component of flow predominates, extremely variable leakage (vertical component of flow) can occur between these aquifers (Peter, 1985; Greene, 1993).
10 Water-Quality Characteristics in the Black Hills Area, South Dakota
Deadwood
Mad
ison
Inya
n K
ara
Gro
up
Formatio
n
Lim
esto
ne
Pre
cam
bria
n m
etam
orph
ican
d ig
neou
s ro
cks
Lim
esto
ne
Min
neka
hta
Min
nelu
saM
adis
on
Lim
esto
neF
orm
atio
n
For
mat
ion
Dea
dwoo
d
Min
nelu
saF
orm
atio
n
Allu
vial
aqui
fer
Pot
entio
met
ricsu
rfac
e of
Mad
ison
aqui
fer
Spr
ing
cond
uit
Wat
erta
ble
Cav
e
Fig
ure
5.
Sch
emat
ic s
how
ing
sim
plifi
ed h
ydro
geol
ogic
set
ting
of th
e B
lack
Hill
s ar
ea.
MA
JOR
AQ
UIF
ER
S
CO
NF
ININ
G U
NIT
Flo
win
g w
ellEX
PLA
NA
TIO
N
LIMEST
ON
E
PLA
TEAU
Hea
dwat
ersp
rings
Art
esia
nsp
rings
Dip
of s
edim
enta
ry r
ocks
exa
gger
ated
Rel
ativ
e th
ickn
ess
NO
T T
O S
CA
LE
Introduction 11
The Deadwood Formation contains the Dead-wood aquifer, which overlies the Precambrian rocks. In general, the Deadwood aquifer serves as a source of water mainly for domestic and municipal users near its outcrop area. There may be some hydraulic connection between the Deadwood and the underlying weathered Precambrian rocks, but regionally the Precambrian rocks act as a lower confining unit to the Deadwood aquifer. Where present, the Whitewood and Winnipeg Formations act as a semiconfining unit overlying the Deadwood aquifer (Strobel and others, 1999). These units locally may transmit and exchange water with the Deadwood aquifer, but regionally are not considered aquifers. Where the Whitewood and Winnipeg Forma-tions are absent, the Deadwood aquifer is in contact with the overlying Englewood Formation, which Strobel and others (1999) included as part of the Madison aquifer.
The Madison aquifer generally occurs within the karstic upper part of the Madison Limestone; however, Strobel and others (1999) included the entire Madison Limestone and underlying Englewood Formation in their delineation of the aquifer. Numerous fractures and solution openings in the Madison Limestone provide extensive secondary porosity in the aquifer. The Madison aquifer generally is confined by low permeability layers in the overlying Minnelusa Formation.
The Minnelusa aquifer occurs within layers of sandstone, dolomite, and anhydrite in the lower portion of the Minnelusa Formation and sandstone and anhy-drite in the upper portion. The Minnelusa aquifer has primary porosity in the sandstone units and secondary porosity from collapse breccia associated with solution of interbedded evaporites and fracturing. The Minnelusa aquifer is confined by the overlying Opeche Shale and by low-permeability layers within the Minnelusa Formation.
The Minnekahta aquifer, which overlies the Opeche Shale, typically is very permeable, but well yields are limited by the aquifer thickness. The over-lying Spearfish Formation acts as a confining unit to the aquifer.
Within the Mesozoic rock interval, the Inyan Kara Group contains an aquifer that is used exten-sively. As much as 4,000 feet of Cretaceous shales act as the upper confining layer to the Inyan Kara aquifer.
Artesian (confined) conditions generally exist within the aforementioned aquifers where an upper confining layer is present. Under artesian conditions,
water in a well will rise above the top of the aquifer in which it is completed. Flowing wells will result when drilled in areas where the potentiometric surface is above the land surface. Flowing wells and artesian springs that originate from confined aquifers are common around the periphery of the Black Hills.
Numerous headwater springs originating from the Paleozoic units at high elevations on the western side of the study area provide base flow for many streams. These streams flow across the central core of the Black Hills, and most streams generally lose all or part of their flow as they cross the outcrops of the Madison Limestone (Rahn and Gries, 1973; Hortness and Driscoll, 1998). Karst features of the Madison Limestone, including sinkholes, collapse features, solution cavities, and caves, are responsible for the Madison aquifer’s capacity to accept recharge from streamflow. Large streamflow losses also occur in many locations within the outcrop of the Minnelusa Formation (Hortness and Driscoll, 1998). Large arte-sian springs occur in many locations downgradient from these loss zones, most commonly within or near the outcrop of the Spearfish Formation. These springs provide an important source of base flow in many streams beyond the periphery of the Black Hills (Rahn and Gries, 1973; Miller and Driscoll, 1998).
Minor Aquifers
In addition to the major aquifers, many other aquifers, such as the Newcastle and alluvial aquifers, are used throughout the study area. In addition, many of the semiconfining and confining units shown in figure 3 may contain local aquifers. These other and local aquifers are considered minor aquifers in this report. This section provides a brief overview from Strobel and others (1999) of the minor aquifers for which water-quality data are available.
Local aquifers may exist in the Spearfish con-fining unit where gypsum and anhydrite have been dis-solved, increasing porosity and permeability; these aquifers are referred to as the Spearfish aquifer in this report. The Jurassic-sequence semiconfining unit con-sists of shales and sandstones. Overall, this unit is semiconfining because of the low permeability of the interbedded shales; however, local aquifers do exist in some formations such as the Sundance and Morrison Formation. These aquifers are referred to as the Sundance and Morrison aquifers in this report.
12 Water-Quality Characteristics in the Black Hills Area, South Dakota
The Cretaceous-sequence confining unit mainly includes shales of low permeability, such as the Pierre Shale; local aquifers within the Pierre Shale are referred to as the Pierre aquifer in this report. Within the Graneros Group, the Newcastle Sandstone contains an important minor aquifer. Because water-quality characteristics are very different between the New-castle aquifer and the other units within the Graneros Group, water-quality data are presented for the Newcastle aquifer separately from the other units within the Graneros Group, known as the Graneros aquifer in this report.
Gravel deposits of Tertiary age and unconsoli-dated units of Quaternary age, including alluvium, colluvium, gravel deposits, and wind-blown deposits, all have the potential to provide water where these units are saturated. In this report, these units are collectively referred to as alluvial aquifers.
Previous Investigations
Numerous reports from previous investigations contain information on the water quality of ground and surface water in the Black Hills area. The investiga-tions described in this section are not exhaustive, but rather are those that either provide regional water-quality information or were done as part of the Black Hills Hydrology Study.
Various investigations have addressed the quality of ground water in the Black Hills area. Water-quality data collected from the Inyan Kara aquifer in the southern Black Hills were presented by Gott and others (1974). Radium concentrations collected from wells completed in the Madison aquifer in western South Dakota were presented by Carda (1975). Numerous water-quality data were collected in western South Dakota during the National Uranium Resource Evaluation (NURE) Program established by the U.S. Department of Energy. Some of the NURE data col-lected in the Black Hills area were presented by Union Carbide Corporation (1979, 1980). Water-quality data collected from the Madison aquifer in Montana, South Dakota, and Wyoming were presented in Busby and others (1983). The quality of ground water in western South Dakota was summarized for 17 aquifers by Meyer (1984), and ground-water pollution problems were summarized in Meyer (1986). Summaries of water-quality samples collected from the Inyan Kara, Minnelusa, and Madison aquifers were presented by
Peter (1985) for the Rapid City area and by Kyllonen and Peter (1987) for the northern Black Hills of South Dakota and Wyoming. Water-quality data with emphasis on selenium in the Inyan Kara aquifer in the Black Hills were presented by Behal (1988). Water-quality data with emphasis on radionuclides for the Deadwood aquifer in the Black Hills were presented by Rounds (1991). Major ion and isotope data for the Madison aquifer in Montana, South Dakota, and Wyoming were presented by Busby and others (1991).
Many investigations on the quality of surface water have been conducted. The general water quality of streams within South Dakota has been reported every 2 years in 305(b) assessment reports prepared by the South Dakota Department of Environment and Natural Resources (1975-99). Water-quality data and results from the Rapid City National Urban Runoff Program were presented by Harms (1983), Harms and others (1983), and Goddard and others (1989). The water-quality effects of contaminated sediments on Whitewood Creek and the Belle Fourche and Chey-enne Rivers were addressed by Cherry and others (1986a, 1986b, 1986c), Goddard (1988, 1989a, 1989b, 1990), and Fuller and others (1988, 1989). Water-quality data, including major ions, properties, trace elements, and pesticides, that were collected during 1988 as part of irrigation drainage programs were pre-sented by Greene and others (1990) for the Angostura Reclamation Unit and by Roddy and others (1991) for the Belle Fourche Reclamation Project. The water quality of streams in Custer State Park following the Galena Forest Fire was presented by Gundarlahalli (1990). Freeman and Komor (1991) presented a com-pilation of water-quality data along Rapid Creek for the period 1946-90, and Williamson and others (1996) pre-sented data on selected trace elements in Rapid Creek. Additional summaries of sources of water-quality data in the Rapid Creek Basin were presented by Zogorski and others (1990). Information about arsenic loads and concentrations in Spearfish Creek were presented by Driscoll and Hayes (1995). Water-quality impacts on surface water from mining were presented by Rahn and others (1996).
Several reports contain water-quality data that were specifically collected as part of the Black Hills Hydrology Study. Water-quality data for selected wells, streams, and springs have been published by Driscoll and Bradford (1994), Driscoll and others (1996), and Driscoll, Bradford, and Moran (2000). Water-quality data for selected streams in Lawrence
Sampling Sites and Methods 13
County were presented by Torve (1991), Williamson (1999), and Williamson and Hayes (2000). Nutrient, chloride, and bacteria data collected during 1988-90 for the Spearfish Creek Basin in Lawrence County were presented by Johnson (1992). Water-quality data from large-discharge springs and selected wells completed in the Madison and Minnelusa aquifers in the southern Black Hills were presented by Whalen (1994) and in northwestern Lawrence County by Klemp (1995). Water-quality data with emphasis on field properties of selected headwater springs in the Black Hills were presented by Wenker (1997).
Acknowledgments
The authors acknowledge the efforts of the West Dakota Water Development District for helping to develop and support the Black Hills Hydrology Study. West Dakota’s coordination of various local and county cooperators has been a key element in making this study possible. The authors also recognize the numerous local and county cooperators represented by West Dakota, as well as the numerous private citizens who have helped provide guidance and support for the Black Hills Hydrology Study. The South Dakota Department of Environment and Natural Resources has provided support and extensive technical assistance to the study. In addition, the authors acknowledge the input and technical assistance from many faculty and students at the South Dakota School of Mines and Technology.
WATER-QUALITY CHARACTERISTICS
Data from the USGS National Water Information System (NWIS) water-quality database, QWDATA, were examined to characterize the water quality of aquifers, streams, and springs in the Black Hills area. QWDATA stores data primarily collected and analyzed by USGS. The data also are transferred to the U.S. Environmental Protection Agency (USEPA) water-quality database, STORET.
Data summarized in this report include samples collected from October 1, 1930, to September 30, 1998. A selection criterion for including a sample as part of this analysis was to have a cation/anion balance within 10 percent. Tables of individual results are not presented in this report, only summaries. Site specific
data can be requested from the USGS or USEPA. For some of the constituents summarized in this report, multiple laboratory reporting limits were used, resulting in censored values at various levels. If the majority of detectable levels were less than some of the censored values, those censored values were removed because they do not provide additional information for describing the data set. For the censored data, boxplots and summary statistics were estimated using a log-probability regression procedure (Helsel and Gilliom, 1985).
Sampling Sites and Methods
Ground-water and surface-water samples col-lected as part of studies along Whitewood Creek have been summarized in previous reports (Goddard, 1988, 1989a; Fuller and Davis, 1989; Fuller and others, 1988, 1989; Goddard and others, 1989) and are not included in this summary. In addition, samples from wastewater treatment plant effluents, some miscellaneous mea-surement sites, and samples from sites obviously affected by abandoned mines are not included. Sam-pling locations for ground water and surface water are presented in figures 6 and 7, respectively. The location of selected surface-water sites in the Rapid Creek Basin is presented in figure 7a. Lists of the ground-water and surface-water sampling sites are presented in tables 15 and 16 in the Supplemental Information section at the end of the report.
For the majority of the samples collected prior to the Black Hills Hydrology Study and for all samples collected during the study, all water-sampling equip-ment was presoaked in a Liquinox solution, thoroughly scrubbed, rinsed with tap water, and then rinsed with deionized water prior to sampling. Samples were collected using acceptable methods at the time; most methods are described by Hem (1985) and Ward and Harr (1990). Field measurements of streamflow, air and water temperature, pH, dissolved oxygen, and specific conductance usually were collected. When more than one site was sampled on a given day, equip-ment cleaning between sites consisted of a deionized water rinse and thoroughly rinsing with well or stream water. After samples were collected, filtered and pre-served, if applicable, they were shipped to the USGS National Water Quality Laboratory (NWQL) for analysis.
14 Water-Quality Characteristics in the Black Hills Area, South Dakota
BUTTE CO
LAWRENCE CO MEADE CO
PENNINGTON CO
CUSTER CO
FALL RIVER CO
WY
OM
ING
SO
UT
H
DA
KO
TA
LIM
ES
TO
NE
PL
AT
EA
U
Whitewood
Spearfish
Maurice
Savoy
SaintOnge
DEADWOOD
Lead
Galena
Nemo
CentralCity
BELLE FOURCHE Minnesela
Newell
Vale
Fruitdale Nisland
STURGIS
Blackhawk
Piedmont
Tilford
Box Elder
RAPID CITY
Hill City
Hermosa
CUSTER
HOT SPRINGS
Edgemont
Roubaix
Keystone
Hayward
Fairburn
Buffalo Gap
Rochford
CascadeSprings
Pringle
Wild
Ditch
NF
orkR
apidC
r
Belle FourcheReservoir
FOURCHE
Victoria
Spring
RapidIrishman
Hawthorn
Gulch
CanyonSouth
Grace
Cool i d ge
Cotton wood
AngosturaReservoir
Iron
Creek
Lit
tle
Castle
Cr
N Fork Castle Cr
Rhoads Fork
Can
yon
Red
BearG
ulch
Creek
Crow
SheridanLake
StockadeLake
DeerfieldReservoir
PactolaReservoir
Indian Cr
Horse
Creek
OwlCreek
BELLE
RIVER
REDWATER R I VE
RC
reek
Spea
rfis
h
Whi
tewoo
d
Cre
ek
Creek
Bear
Butte
Elk
Elk
Creek
Creek
Creek
Boxelder
Rapid
Creek
Creek
Creek
Creek
Creek
Creek
Creek
Cre
ek
S. Fork
S. Fork Rapid Cr
Battle
French
Beaver
Creek
Creek
Cre
ek
Creek
FallR
Hat
Cre
ek
Creek
Horsehead
CHEYENNE
RIVER
Cot
tonw
ood
CreekHay
Spokane
Lame
Johnny
Bea
ver
Cre
ek
Robison
Gulch
Gulch
Castle
Cas
tle
Bear
Reno
Little
Strawberry
Creek
Gulch
Hig
gins
Creek
C reekCr
Cr
Cr
CrE
ast
CreekB
otto
m
False
Spea
rfis
h
Squaw
Annie
Spearfish
North
Canal
Canal
IronDraw
Angostura
Canal
Cox Lake
MurrayDitch
RedwaterCanal
Gulch
SheridanLakeTributary
CitySprings
Inlet
Wind CaveNational Park
CUSTER
STATE
PARK
WindCave
HarneyPeakx
0 10 20
0 10 20 MILES
KILOMETERS
Inyan KaraMinnekahta
MinnelusaMadisonDeadwoodPrecambrian
Alluvial
GranerosNewcastle
Pierre MorrisonSundance
Spearfish
EXPLANATION
Figure 6. Location of ground-water sampling sites.
Base modified from U.S. Geological Survey digital data, 1:100,000Rapid City, Office of City Engineer map, 1:18,000, 1996Universal Transverse Mercator projection, zone 13
104o 45' 103o30'
15' 103o
30'
44o45'
15'
44o
45'
30'
43o15'
MAJOR AQUIFERS
MINOR AQUIFERS
Sampling Sites and Methods 15
BUTTE CO
LAWRENCE CO MEADE CO
PENNINGTON CO
CUSTER CO
FALL RIVER CO
WY
OM
ING
SO
UT
H
DA
KO
TA
LIM
ES
TO
NE
PL
AT
EA
U
Whitewood
Spearfish
Maurice
Savoy
SaintOnge
DEADWOOD
Lead
Galena
Nemo
CentralCity
BELLE FOURCHE Minnesela
Newell
Vale
Fruitdale Nisland
STURGIS
Blackhawk
Piedmont
Tilford
Box Elder
RAPID CITY
Hill City
Hermosa
CUSTER
HOT SPRINGS
Edgemont
Roubaix
Keystone
Hayward
Fairburn
Buffalo Gap
Rochford
CascadeSprings
Pringle
Wild
Ditch
NF
orkR
apidC
r
Belle FourcheReservoir
FOURCHE
Victoria
Spring
RapidIrishman
HawthornG
ulch
Canyon
South
Grace
Cool i d ge
Cotton wood
AngosturaReservoir
Iron
Creek
Lit
tle
Castle
Cr
N Fork Castle Cr
Rhoads Fork
Can
yon
Red
BearG
ulch
Creek
Crow
SheridanLake
StockadeLake
DeerfieldReservoir
PactolaReservoir
Indian Cr
Horse
Creek
OwlCreek
BELLE
RIVER
REDWATER R I VE
RC
reek
Spea
rfis
h
Whi
tewoo
d
Cre
ek
Creek
Bear
Butte
Elk
Elk
Creek
Creek
Creek
Boxelder
Rapid
Creek
Creek
Creek
Creek
Creek
Creek
Creek
Cre
ek
S. Fork
S. Fork Rapid Cr
Battle
French
Beaver
Creek
Creek
Cre
ek
Creek
FallR
Hat
Cre
ek
Creek
Horsehead
CHEYENNE
RIVER
Cot
tonw
ood
CreekHay
Spokane
Lame
Johnny
Bea
ver
Cre
ek
Robison
Gulch
Gulch
Castle
Cas
tle
Bear
Reno
Little
Strawberry
Creek
Gulch
Hig
gins
Creek
C reekCr
Cr
Cr
CrE
ast
CreekB
otto
m
False
Spea
rfis
h
Squaw
Annie
Spearfish
North
Canal
Canal
IronDraw
Angostura
Canal
Cox Lake
MurrayDitch
RedwaterCanal
Gulch
SheridanLakeTributary
CitySprings
Inlet
Wind CaveNational Park
CUSTER
STATE
PARK
WindCave
HarneyPeakx
0 10 20
0 10 20 MILES
KILOMETERS
Headwater springCrystalline coreArtesian springExteriorOther
Figure 7. Location of selected surface-water sampling sites by group.
Base modified from U.S. Geological Survey digital data, 1:100,000Rapid City, Office of City Engineer map, 1:18,000, 1996Universal Transverse Mercator projection, zone 13
OUTCROP OF MADISON LIME- STONE (from Strobel and others, 1999)
HYDROGEOLOGIC SETTINGS
SURFACE-WATER SAMPLING SITES BY GROUP
Limestone headwaters
OUTCROP OF MINNELUSA FORMATION (from Strobel and others, 1999)
Crystalline core
Loss zones and artesian springs--Outer extent approximates the outer extent of the Black Hills areaExterior plains
EXPLANATION104o 45' 103o30'
15' 103o
30'
44o45'
15'
44o
45'
30'
43o15'
16 Water-Quality Characteristics in the Black Hills Area, South Dakota
T. 2 N.
T. 1 N T. 1 S.
T. 2 S.
PE
NN
ING
TO
N C
OU
NT
Y
CU
ST
ER
CO
UN
TY
LAWRENCE COUNTY
WYOMING
MEADE COUNTY
SOUTH DAKOTA
R. 2
E.
R. 1
E.
R. 3
E.
R. 4
E.
R. 5
E.
R. 6
E.
R. 7
E.
R. 8
E.
R. 9
E.
R. 1
0 E
.R
. 11
E.
104o
R. 1
2 E
.
Ells
wor
thA
ir F
orce
Bas
e
RA
PID
CIT
Y
Cre
ston
Big
Ben
d
Silv
er C
ity
Roc
hfor
d
Dee
rfie
ld
Cro
oks
Tow
er
44o
15'
44o
103o 3
0'
T. 3 N.
Cap
uta
Far
min
gdal
e
RapidCr
ee
k
Dee
rfie
ld D
aman
d R
eser
voir
Pac
tola
Dam
and
Res
ervo
irCastle
Cre
ek
Rhoads
FkSouth
For
k
Vic
toria
Cr
CHEYENNE
RIVER
North Fork
Rap
id
Cre
ek
Can
yon
Lak
eC
anyo
nL
ake
0640
9000
0640
9000
0641
1500
0641
250006
4140
00
0641
8900
0642
1500
0640
9000
0641
1500
0641
2500
0641
0500
0641
0500
0641
4000
0641
8900
0642
1500
010
20
010
20K
ILO
ME
TE
RS
MIL
ES
EX
PLA
NA
TIO
NR
AP
ID C
RE
EK
BA
SIN
BO
UN
DA
RY
SU
RF
AC
E-W
AT
ER
SA
MP
LIN
G S
ITE
--
Num
ber
indi
cate
s si
te id
entif
icai
ton
Fig
ure
7a.
Loc
atio
n of
sel
ecte
d su
rfac
e-w
ater
sam
plin
g si
tes
in th
e R
apid
Cre
ek B
asin
.
Bas
e m
odifi
ed fr
om U
.S. G
eolo
gica
l Sur
vey
1:50
0,00
0 H
ydro
logi
c U
nit M
ap, 1
978
SO
UT
HD
AK
OT
AB
lack
Hill
s
Rap
idC
reek
Bas
in
103o