Figure 4. Conceptual hydrogeologic cross section showing relationships among shallow groundwater, the Fort Union Formation, topography,and streams draining the Beartooth Mountain Front (modified from Slagle, 1986). The water table is dashed where confidence is low.
5,200
5,000
4,800
4,600
4,400
4,200
4,000
Quaternary terrace gravel
Sprin
g
200’
A A’
Relativelyimpermable layer
Tertiary Fort Union Formation
Cretaceous Montana Group
Bend
in s
ectio
n
20 miles
Feet
abo
ve m
ean
sea
leve
l
water table
Perchedwater table
Figure 1. Location map showing area of groundwater contours and major structural features within Carbon–Stillwater study area.
BEARTOOTHMOUNTAINS
Carbon–Stillwater Ground Water Characterization Area
0 10 20 miles5
Location
Scale 1:750,000Projection: Montana State PlaneDatum: NAD 83
PRYORMOUNTAINS
Montana
Canada
Major faultsStreams
Area of shallowgroundwater contours
CRAZY MOUNTAINS
BASIN
! Towns
EXPLANATION
!
!
!
!
!
14
12
10,16 south of drainage divide
4,9
2
7
6
5
133,11,15
81
all of Carbon County
all of StillwaterCounty
Nye
Rapelje
Columbus
Fromberg
Red Lodge
Stillwater Co.
Carbon Co.
Bearcreek
60
50
40
30
20
10
0
n=63n=171 n=117n=9 n=94
Rep
orte
d w
ell y
ield
(gpm
)
KetTfu Khc KjrTKi
Key
95th75th
Median25th
5th
Percentile
Figure 3. Distribution of driller-reported well yields among Fort Union (Tfu), intrusive rock (TKi), Hell Creek (Khc), Judith River (Kjr), and Eagle Sandstone (Ket) aquifers. Most bedrock wells yield less than 20 gpm.
Figure 2. The location of previous water resource investigations. Numbers in the figure relate to numbers in the References section. The size of number relates to the areal extent of the investigation (i.e. # 4 covers Carbon County whereas #13 was a municipal water supply investigation for the town of Bearcreek).
NyeNye
RapeljeRapelje
ColumbusColumbus
FrombergFromberg
Red LodgeRed Lodge
Lake BasinLake BasinFault ZoneFault Zone
Yellowston e River
Clarks F
ork
Rive
r
Lake BasinLake Basinsubareasubarea
Reed Point Syncline
BIGBIG HORN HORN BASIN BASIN
MONTANAMONTANAWYOMINGWYOMING
Nye-Bowler Lineament
From
berg
Fau
lt
From
berg
Fau
lt
Nye
Rapelje
Columbus
Fromberg
Red Lodge
Lake BasinFault Zone
Yellowston e River
Clarks F
ork
Rive
r
Lake Basinsubarea
Reed Point Syncline
BIG HORN BASIN
MONTANAWYOMING
Nye-Bowler Lineament
From
berg
Fau
lt
Jan-02 Jan-03 Jan-04 Jan-05 Jan-06
199749 191006 106097
Fee
t of C
hang
e (s
olid
line
s ev
ery
10 fe
et)
Jan-02 Jan-03 Jan-04 Jan-05 Jan-06
144103 145486
Fee
t of C
hang
e (s
olid
line
s ev
ery
10 fe
et)
199749191006
154738
199495
131617
144103
145486
106097
Jan-02 Jan-03 Jan-04 Jan-05
186083 183680Kb Kjr
Khc Tfu Tfu
Tfu Khc
186083183680
Figure 5. Hydrographs from the Bearpaw confining unit (Kb) and Judith River aquifer (Kjr) show minor seasonal fluctuations from 2002 to 2004 (6-digit GWIC identification numbers).
Figure 6. Hydrographs from the Fort Union (Tfu) and Hell Creek (Khc) aquifers show similar seasonal fluctuations from 2002 to 2006 (6-digit GWIC identification numbers).
Jan-02 Jan-03 Jan-04 Jan-05 Jan-06
154738 199495 131617
Fee
t of C
hang
e (s
olid
line
s ev
ery
10 fe
et)
Qsc Tfu Tfu
Figure 7. Hydrographs from the Fort Union (Tfu) aquifer show similar timing but different magnitude of seasonal fluctuations when compared to unconsolidated sediments (Qsc, diamonds and blue line) from 2002 to 2006. The similar response in each year suggests irrigation canal leakage is an important source of groundwater recharge in this area (6-digit GWIC identification numbers).
Fee
t of C
hang
e (s
olid
line
s ev
ery
10 fe
et)
Figure 8. Hydrographs from the Fort Union (Tfu) and Hell Creek (Khc) aquifers show little or no seasonal fluctuation from 2002 to 2005 (6-digit GWIC identification numbers).
R 19 E R 20 E R 21 E R 22 E
T 4 N
T 3 N
T 2 N
R 23 E
T 1 N
T 1 S
T 2 S
T 3 S
T 4 S
T 5 S
T 6 S
T 7 S
T 8 S
T 9 S
R 23 ER 22 ER 21 ER 20 E
R 19 E
R 18 E
R 17 E
R 16 E
T 9 S
T 8 S
T 7 S
T 6 S
T 5 S
T 4 S
R 15 E
R 15 E R 16 E
T 3 S
R 17 E
T 2 S
T 1 S
T 1 N
T 2 N
T 3 N
R 18 E
R 24 E
T 4 N
A
A'
TKi
Kjr
Ket
Kcg
Kk
J-*
Mm
D-_
Kmg
Tan- to yellowish-gray sandstone, sandy claystone, clay-stone, shale, and coal. Coalbeds are mostly found between the Beartooth Mountain Front and Yellowstone River. The Linley Conglomerate is a reddish-brown to gray-brown interbedded, conglomerate, coarse-grained sandstone, siltstone, and mudstone. The formation thickens as much as 5,000 ft near the Beartooth Mountain Front.
Widely used aquifer contains saturated, laterally discontinuous sandstone and coal that yield water to wells, seeps, and springs. Wells completed in the Linley Conglomerate produce poorly and drillers’ logs often discribe drill cuttings as “granite.” Well drillers report a median yield of 11 gpm with a median DWE and TD of 64 and 150 ft, respectively.
Intrusive RocksLocal Aquifer
82
Hell Creek Aquifer
412
Bearpaw ShaleConfining Unit
200
Judith RiverAquifer
315
Sliderock Mountain stratovolcanic rocks, and dioriteor diorite porphyry combined with Tertiary or Late Creta-ceous age felsic rocks.
Intrusive rocks are not generally extensive enough to be considered regional aquifers, but locally do yield water to wells, seeps, and springs from saturated fractures. Well drillers report a median yield of 15 gpm with a median DWE and TD of 60 and 85 ft, respectively.
Interbedded, light-brownish-gray, cliff-forming, fine-grained, thin- to thick-bedded sandstone; gray mud-stones and fissile shale. Sandstone beds are generallythicker east of the Clarks Fork of the Yellowstone River than to the west. Total thickness ranges from 350 to 1,000 ft.
Laterally continuous aquifer with saturated sandstone that yields water to wells. Well drillers report a median yield of 10 gpm with median DWE and TD of 50 and 110 ft, respectively. Hell Creek aquifer wells are generally near the outcrop and relatively few wells penetrating overlying units to access the aquifer.
Dark-gray, fissile, thin, mostly greenish-gray shale.Bentonite beds, near the middle; thin sandstonebeds at the top. Thins from approximately 800 ft in the eastern part of the study area to 100 ft in the west.
Laterally continuous, but not an aquifer except near outcrop where sandstone may yield poor-quality water to properly constructed wells. Well drillers report a median yield of 15 gpm with a median DWE and TD of 40 and 70 ft, respectively.
Fort UnionAquifer
606
Brownish-gray, sandy shale and light-brown to paleyellowish-brown clayey, very-fine- to fine-grainedlenticular sandstone beds up to 10 ft thick. Contains greenish and maroon-gray mudstones, and poor quality coal. Sandstone generally occurs near top. Total thickness from 700 to 1,000 ft.
Laterally continuous aquifer with sandstone yielding groundwater to wells. Well drillers report a median yield of 10 gpm with a median DWE and TD of 60 and 125 ft, respectively.
Brownish-gray, fissile, shale and minor clayey sandstone. Total thickness ranges from 100 to 300 ft.
Laterally continuous, but not an aquifer, except near outcrop where sandstone may yield water to wells.
Claggett Shale Confining Unit
66
Eagle SandstoneAquifer
150
Light-gray, brownish-gray to pale orange, very fine- tomedium-grained sandstone with interbedded brownish-gray to medium dark gray shale, sandy shale, siltstone and sandstone. Telegraph Creek sandstones thicken upward becoming cliff- and ridge-forming Eagle Sandstone. Total thickness from 300 to 450 ft.
Laterally continuous aquifer with sandstone yielding water to wells, seeps, and springs. Well drillers report a median yield of 12 gpm with median DWE and TD of 90 and 200 ft, respectively. Wells often penetrate through the Claggett confining unit to access the Eagle Sandstone aquifer. However, most wells are located near the outcrop.
Montana Group
<1
Bearpaw Shale through Telegraph Creek Formation un-divided. Occurs in T. 6 S., R. 18 E., and T. 7 S., R. 18 E.only. Aquifer potential unknown.
ColoradoGroupConfining Unit
95
Niobrara Formation through Thermopolis Shale; FallRiver Sandstone.
Laterally continuous but not an aquifer except near outcrop where sandstone beds may yield water to wells.
Kootenai Aquifer*
Madison Aquifer* Jurassic through Pennsylvanian aquifers; non-aquifers*
Khc
Kb
Kcl
Tfu
65
1.8
543
144
Terti
ary
Bed
rock
Uni
ts
Alluvial sand and gravel, found in recent river valleysand on abandoned floodplains (terraces). Also includes terraces deposited by glacial meltwater streams.
Sediments,coarse-grained
466
Sediments, fine-grained
189
Sandy silt or clay deposited as slope wash or glacial till.Includes modern lake, older lake, and landslide deposits. Not an aquifer.
Map Units /Square Miles Lithology and water availabilityLabels
Qsc
Qsf
Devonian through Cambrian aquifers; non-aquifers* Granitic rocks; non-aquifer* Agn
* aquifers and non-aquifers not used to generate groundwater contours TD = total depth, DWE = depth water enters (usually top of well screen)Ma = millions of years before present
Qua
tern
ary
Unc
onso
lidat
ed U
nits
TKi
Kjr
Ket
Kcg
Kmg
Khc
Kb
Kcl
Tfu
Qsc
Qsf
Agn
Qsf
Qsf
Qsc
Qsc
Kcg
Qsc
Qsc
KjrKb
Kcl
Tfu
Qsc
Kcl
Tfu
Tfu
Kjr
Ket
Kk
J-*Mm
Khc
Kb
Kcl
Agn
Qsc
Kjr
Ket
Hydrostratigraphy
Khc
Kb
Khc
KjrKcl
KetKcg
Tfu
Kjr
KjrKb
Kcl
Ket
Ma
Cre
tace
ous B
edro
ck U
nits
Cam
bria
n th
roug
h Ju
rass
ic B
edro
ck U
nits
Ma
Ma
Ma
D-_
Yellowstone River
Yellowstone River
Big Lake
CooneyReservoir
Clar
ks F
ork o
f th
e Ye
llow
stone
Rock
Cree
k
Elbow CreekRed Lodge Creek
Stillwater R
iver
Trout Creek
Fishtail Cree
k
Wes
t Ros
ebud
Cre
ek
Ea
st Ros
ebud
Cree
k
East White Beaver CreekKeyser Creek
Valley Creek
Bear Creek
Cottonwood Creek
Silv
er T
ip C
reek
Bluewater Creek
Canyon Creek
Cedar Creek
Lost Creek
Painted Robe Creek
Still
w ater
Rive
r
3,600
4,000
4,400
4,200
5,200
4,400
4,800
4,400
4,400
4,400
4,000
4,400
4,600
4,000
4,200
3,400
4,200
4,000
4,400
5,000
4,200
4,000
4,600
4,600
4,600
4,000
5,000
5,200
5,600
5,400
4,200
3,60
0
4,600
4,200
4,400
5,800
6,000
5,600
5,000
4,800
4,200
4,80
0
4,400
4,800
4,80
0
4,800
4,400
4,800
3,80
0
4,80
0
4,80
0
4,400
3,800
4,800
5,000
5,000
5,400
5,800
4,600
4,200
4,000
4,400
4,000
4,000
4,000
3,800
4,200
4,600
4,600
4,200
4,200
4,200
4,600
3,80
0
3,800
3,600
4,000
4,200
3,800
4,8004,
0004,
2004,
400
4,60
0
4,80
0
3,800
4,200
4,8005,000
3,800
3,700
3,500
3905
3904
4362
4120
4796
4837
4535
3968
5055
3825
6106 6017
4900
4763
5148
4375
4138
4006
4085
4515
4068
40223955 4084
393039293883
4048
4447 3980 3975
39574146
3939
395739483962
3948394139394021
40234669 394939363949
3943
42974140 40004831
3953
39523953
40943998
4694 40944754
4731
45514750 3941
3919 3924
3929
3898
42084637
44934469 4406
43544647 4519
4161
4088 41834070
4143
41474086408340954049
429942774286
42014290
40024002
40064131
40824065
41244135
40634196 4207
4200
4846
4094
40944099
4144
41014096
44934364 4752
4230426943684346
40023772
4043
39833969
40074004
3824
41324128
3967
3962
41554558 4059
40604052
402440263999
39574060
4000400140853988
39934387 39124384 3877
4239
42214251 41214218 4365
35553953
366638083710
3816 4185363136254241
3771 38383848
36084240
41234313
348137753844
3991 344440064399 36163827
3695
3330
4351370342364511
4262 3582
4002 36063592 3473
37023701
3532
36563620
34104823 35973734
3685
3960
397446604309
3975 45833985
3912
3847
39084498 3945 3744
3948 38554314
40534291 40094256
39984267
3975 41594004 4093 358941764304
3833428043084305
4299
41784232
4247 38324181
419737424512
4490427841334399 4321
44554367
43573861
4359 43634362
39504243
42394586 3700 3502
3820384946613851
4267
4219
4840 37523721 3565 3689
3787 33953802
43894427
4358
463949084032
3825
3890 379838003700
46164240
40564236
3909
46014275
4272 37854659
44004766
4544
46674315
490443714549
4666 44535360 3916400740514055
5148
3698
4449479144564962 4198
406941614649
4683 409142364587 4518 4240
4110
44694470
45654806
472945784578
46074137
48934602 4340
4956
43244329 411541014492 4090
39835215 498253655252
45904594
504550485052
5487 387954095497 455850795711
57234295 4290
54764405 3618
5483 50454394
3947436545244511 4413 4462
46544653
54115115 5041 4443
5237 51705322 4963
4503 4288
50745080
3688
44184130
4069
40504045
4212
4209
3801 3959 39583928
36853875 36883984
38463849
37443883
3880
4143
38563879
42064204 3554
36704055
39793760 380838163817
37183663
37243717
39723974
3683
37283792
3714
37003686 39083682 4185
3781373838113667
36904766
48275388 4610
37224616
47085469 4612 4240
45974816 4749 4712
4727496651765320
46764684 4752 3677
50854753
4829
375153615362
49284937
3634
5357 51564900 4768 4976 4558
37805352 4848 489649934885
50315400
472050564900
488351545431
4962574336683666
5152 512936813680
5327 5213
5088
53145392 5147
5199519052563675
3791
538554195242
5464
4155 3712
53345355
377254565460 38015489
5380
42265578
55305564
558037933806
38195659
5600559757197371
736757115716
3790 38664483 4368
4360
57715775 56086008
560859384250
6025 41596053
409563086312
38805710
5865
5849 4677
417360176027 3996
39373900
394342424068
4162
44463875 4291
427240774076
6657 4205
430841214296
4254
40854306431251385140
47704024 4337
5529
4816
4360*
4772*
4486*
4952*
5440*
4996*
5632*
4232*
4493*
5568*
4485*
4160*
3714*
3878*
3755*
3640*
3475*
3756*
4018*
3810*
3765*
4605*
3957
6005
4666
3682
4283
Lake Basin subarea contoursby Reiten and others (in preparation).
Maps may be obtained from: Publications Office Montana Bureau of Mines and Geology
1300 West Park StreetButte, Montana 59701-8997
Phone: (406) 496-4174Fax: (406) 496-4451
http://www.mbmg.mtech.edu
.
Scale 1:150,000Projection: Montana State Plane
Datum: NAD 83
0 5 10
Miles
4,800
4831
EXPLANATION FOR MAP
Lakes
River/stream
Township boundary
Towns
Contours show lines of equal water level altitude in feet above mean sea level for bed-rock units. Contour interval is 100 feet and dashed where approximated.
4831*
Inventoried spring
Inventoried bedrock well with measured water level in feet above mean sea level. At some locations, water levels were measured twice as indicated by two water-level altitudes.
Inventoried bedrock well with driller-reported water level in feet above mean sea level.Supplemental bedrock well with driller-reported water level in feet above mean sea level.
4838
4831
Beartooth Mountain Front
Beartooth Mountain Front
The Tertiary Fort Union Formation is a regional source of groundwater; however, it mainly exists in the southern part of the map area. Water-bearing materials (sandstone or coal) in the Fort Union Formation can be laterally discontinuous, causing difficulty predicting drilling depths. In areas topographically separated from the Front, well depths can vary across short distances. The older Cretaceous formations alternate between shale and sandstone. The Hell Creek aquifer (Hell Creek, Lance and Fox Hills Formations combined), the Judith River aquifer (Judith River Formation), and Eagle Sandstone aquifer (Eagle Sandstone and Telegraph Creek Formation com-bined) are the other main bedrock aquifers. These units underlie most of the map area, but are generally only accessed where they are exposed at, or close to the surface. Confining units include the Bearpaw Shale, Claggett Shale, and Colorado/Montana groups; however, near the outcrop these units do yield small amounts of water to wells. Jurassic through Cambrian rocks crop out in small areas near the Front; these outcrops are nearly vertical. Due to the limited outcrops in the map area and their vertical nature, wells completed in Jurassic through Cambrian age rocks were not used in map construction (see Hydrostrati-graphic column). Figure 3 summarizes the driller-reported yields from wells completed in bedrock aquifers. Median yields range from 10 to 15 gallons per minute (gpm). Reported yields from Hell Creek and intrusive rock aquifers have the largest range, whereas yields from the Eagle Sandstone and Judith River aquifers have the smallest range. The main sources of aquifer recharge are infiltration of precipitation, stream losses, and irrigation. Most
recharge occurs in the spring and summer during snowmelt runoff and storm events. Precipitation is most abundant along the Front and in the uplands surrounding the Lake Basin subarea. Irrigation canals provide significant recharge to bedrock and overlying alluvial aquifers along Rock Creek near Red Lodge. Aquifer discharge is primarily to streams, springs, evapotranspiration, and wells. Groundwater generally flows from high-altitude recharge areas toward low-altitude discharge areas. South of the Yellowstone River, several upland areas are topographically separated from the high-altitude recharge area along the Front. Wells in these areas are recharged locally, generally yield
less, and are more sensitive to land-use changes or climatic variability (fig. 4). The figure shows shallow groundwater in the Fort Union aquifer where the water table generally mimics topography; locally, impermeable layers create a perched water table. Discharge from the perched system forms an intermittent spring. The cross section in figure 4 includes two topographic highs separated from the Front. The groundwater surface is probably mounded beneath these areas of local recharge, but there are no data to estimate water-level elevations. Groundwater contours generally mimic topography, with groundwater divides coincident with major topo-graphic ridges and river bottoms. South of the Yellowstone River, the potentiometric surface slopes north, northeast, and east away from the Front toward the major river valleys. North of the Yellowstone River, the potentiometric surface slopes either southward to the Yellowstone River Valley or from all directions into the Lake Basin. Depth to water in wells varies from about 250 ft in the uplands to about 10 ft below land surface in the river valleys.
46°00'
109°00'
46°00'
45°30'
45°00'109°00'
45°30'
Montana Ground Water Assessment Atlas 6, Map 32015
Montana Bureau of Mines and GeologyA Department of Montana Tech of The University of Montana
1) Bartos, T.T., Eddy-Miller, C.A., Norris, J.R., Gamper, M.E., and Hallberg, L.L., 2005, Water-quality characteristics of Quaternary unconsolidated-deposit aquifers and Lower Tertiary aquifers of the Bighorn Basin, Wyoming and Montana, 1999–2001 Scientific Investigations Report 155 p.
2) Buck, F.E., 1946, History of land and water use on irrigated areas: Water Resources Survey, Stillwater County, Montana, 32 p.
Berg, R.B., Lonn, J.D., and Locke, W.W., 1999, Geologic map of the Gardiner 30' x 60' quadrangle, south-central Montana: Montana Bureau of Mines and Geology Open-File Report 387, 9 p., 2 sheets, scale 1:100,000.
Carstarphen, C.A., Smith, L.N., Mason, D.C., LaFave, J.I., and Richter, M.G., 2007, Data for sites visited during the Carbon–Stillwater Ground-Water Characterization Study: Montana Bureau of Mines and Geology, Ground Water Assessment Atlas 6, part B, Map 1, open-file version, 1 sheet, scale 1:250,000.
3) Carstarphen, C.A., Patton, T.W., and LaFave, J.I., 2014, Water levels in the Upper West Bench alluvial aquifer, Red Lodge, Montana: Montana Bureau of Mines and Geology Information Pamphlet 8, 8 p.
4) Darlinton, E.V., 1969, Groundwater inventory Carbon County Montana: Helena, Montana Water Resources Board, 40 p.5) Feltis, R.D., and Litke, D.W., 1987, Appraisal of water resources of the Boulder and Stillwater River basins, including
the Stillwater Complex, south-central Montana: Montana Bureau of Mines and Geology Memoir 60, 121 p., 3 sheets.6) Kuzara, S., Meredith, E., and Gunderson, P., 2012, Aquifers and streams of the Stillwater and Rosebud watersheds,
Montana: Montana Bureau of Mines and Geology Open-File Report 611, 130 p.7) Levens, Russell, 2009, Groundwater conditions at the Horse Creek temporary controlled groundwater area: Montana
Department of Natural Resources and Conservation, 71 p.8) Levings, J.F., 1986, Water resources of the Clarks Fork Yellowstone River valley, Montana: Montana Bureau of Mines and
Geology Hydrogeologic Map 8, 3 sheets.
Lopez, D.A., 2000a, Geologic map of the Big Timber 30' x 60' quadrangle, south-central Montana: Montana Bureau of Mines and Geology Open-File Report 405, 17 p.,1 sheet, scale 1:100,000.
Lopez, D.A., 2000b, Geologic map of the Billings 30' x 60' quadrangle, Montana: Montana Bureau of Mines and Geology Geologic Map 59, 1 sheet, scale 1:100,000.
Lopez, D.A., 2000c, Geologic map of the Bridger 30' x 60' quadrangle, Montana: Montana Bureau of Mines and Geology Geologic Map 58, 1 sheet, scale 1:100,000.
Lopez, D.A., 2001, Preliminary geologic map of the Red Lodge 30' x 60' quadrangle, south-central Montana: Montana Bureau of Mines and Geology Open-File Report 423, 17 p., 1 sheet, scale 1:100,000.
Lopez, D.A., 2005, Geologic Map of the Red Lodge area, Carbon County, Montana: Montana Bureau of Mines and Geology Open-File Report 524, 15 p., 1 sheet, scale 1:48,000.
9) McDermott, A.D., 1966, Water resources Survey: State Water Conservation Board, Carbon County, Montana, 85 p. Montana Department of Commerce Census and Economic Information Center website, accessed 1/3/2014,
http://ceic.mt.gov/Population/PopProjections_AllCountiesPage.aspx 10) Peterson, D.A., Miller, K.A., Bartos, T.T., Clark, M.L., Porter, S.D., and Quinn, T.L., 2004, Water quality in the
Yellowstone River Basin, Wyoming, Montana and North Dakota, 1999–2001: U.S. Geological Survey Circular, 34 p.11) Reiten, J.C. (in preparation), Planning tools for developing and managing water resources near Red Lodge, Montana:
Phase 1, Hydrogeology and water balance of the East and West Bench aquifers: Montana Bureau of Mines and Geology Open-File Report.
12) Reiten, J.C., Hanson, J., Erickson, J.L., and Schwartz C. (in preparation), Improving soil productivity and water quality through land-use changes in south-central Montana: Montana Bureau of Mines and Geology Open-File Report.
13) Rose, J.C., 2000, Hydrogeologic Assessment of the town of Bearcreek Municipal Water System for Groundwater under the Direct Influence of Surface Water Program: Montana Bureau of Mines and Geology Open-File Report 401-M, 20 p.
14) Rose, J.C., 2000a, Hydrogeologic Assessment of the Rapelje Water User Association Water Supply for Groundwater under the Direct Influence of Surface Water Program: Montana Bureau of Mines and Geology Open-File Report 401-M, 37 p.
Ritter, D.F., 1967, Terrace development along the front of the Beartooth Mountains, southern Montana: Geological Society of America Bulletin, v. 78, p. 467–484.
Slagle, S.E., 1986, Hydrology of Area 48, Northern Great Plains and Rocky Mountain Coal Provinces: U.S. Geological Survey, Water Resources Investigations, Open-File Report 84-141, 91 p.
15) Waren, Kirk, 2000, Groundwater levels at the south end of the Red Lodge Bench near Red Lodge, Montana: Montana Department of Natural Resources and Conservation, unpublished report, March 2000, 21 p.
Wilde, E.M., and Porter, K.W., 2000, Geologic map of the Roundup 30' x 60' quadrangle, central Montana, Montana Bureau of Mines and Geology Open-File Report 404, 1 sheet, scale 1:100,000.
Wilde, E.M., and Porter, K.W., 2001, Geologic map of the Harlowton 30' x 60' quadrangle, central Montana, Montana Bureau of Mines and Geology Open-File Report 434, 1 sheet, scale 1:100,000.
16) Zelt, R.B., Boughton, G.K., Miller, K.A., Mason, J.P., and Gianakos, L.M., 1999, Environmental setting of the Yellowstone River basin, Montana, North Dakota, and Wyoming: U.S. Geological Survey, Water Investigations Report 98-4269, 112 p.
Water levels in wells fluctuate in response to changes in aquifer storage. The magnitude of the fluctuation depends on the balance between recharge and discharge, as well as aquifer storativity. Water levels rise when recharge exceeds discharge and decline when the opposite occurs. Representative hydrographs show different patterns through-out the map area. Lake Basin subarea hydrographs from wells completed in the Judith River aquifer and Bearpaw Shale confining unit show little seasonal change (fig. 5), suggesting recharge equals discharge. South of the Yellowstone River, hydrographs from wells completed in Fort Union and Hell Creek aquifers show approximate seasonal fluctua-tions with similar timing (fig. 6). Water levels rise during the spring in response to precipitation/runoff, and drop in the fall because of decreased recharge and evapotranspiration. Domestic well pumping may contribute to the somewhat erratic shape of some hydrographs. Hydrographs in the Red Lodge area (fig. 7) show more consistent seasonal fluctua-tions compared to the hydrographs in figure 6. The hydrographs shown in figure 6 are from water wells northwest of Red Lodge in areas topographically separated from the Front; these wells show little influence from irrigation. Water levels in bedrock aquifers near Red Lodge show a uniform response, suggesting recharge is strongly controlled by leakage from overlying alluvial aquifers and irrigation canals. Figure 7 shows two hydrographs from Fort Union aquifer wells on opposite sides of Rock Creek, and a shallow well completed in unconsolidated Quaternary alluvium. The timing and magnitude of water-level change for each well is consistent during the period of record. However, the magnitude of annual fluctuation varies; the alluvial well shown in figure 7 fluctuates as much as 35 ft annually, whereas the east bench Fort Union well fluctuates about 12 ft, and the west bench Fort Union well fluctuates about 7 ft per year. In contrast, water-level fluctuations in two Fort Union and one Hell Creek wells east of the Clarks Fork of the Yellowstone show little or no seasonal fluctuation (fig. 8). These wells are located away from irrigation canals and in a dry part of the study area.
Map use This map presents the distribution of MBMG inventoried wells, generalized surface geology, and groundwater altitude within 200 ft of the land surface. The map intends to give the user a regional overview of groundwater occur-rence and altitude, and aid with initial conceptual models for large-scale investigations. Groundwater contours shown here are intended to be accurate within one contour interval. Contours may be less accurate in areas with high topo-graphic relief. Figures 3, 5, 6, 7, and 8 show descriptive statistics of driller-reported yields per aquifer, and representative hydrographs for areas along the Front and from the Lake Basin subarea. Water-well drillers measure yields using different methods, which can lead to errors. Groundwater contours portray conditions from August 2001 to November 2005 within 200 ft of the land surface. Water-well and borehole records are continuously submitted to GWIC; up-to-date information can be accessed to supplement the data presented here at http://mbmggwic.mtech.edu. This map is not intended to be used at scales larger than 1:150,000.
Acknowledgments The authors appreciate the assistance from many individuals and organizations in the completion of this map. Funding for this work was provided by the MBMG Ground Water Characterization Program. Well owners who allowed collection of the data necessary for map construction and MBMG researchers who collected the data are gratefully acknowledged. Susan Smith (MBMG) lent her cartographic skills to construct figures and cross sections and Paul Thale (MBMG) provided technical assistance and with the GIS analysis. Reviews by MBMG staff: John Metesh, Tom Patton, John LaFave, James Madison, Jon Reiten, Phyllis Hargrave, and Monte Smith (DEQ) added to the clarity of map and text.REFERENCES (Numbered items are keyed to areas shown in figure 2)
Author’s Note: This map is part of the Montana Bureau of Mines and Geology (MBMG) Ground WaterAssessment Atlas for the Carbon–Stillwater area. It is intended to stand alone and describe a single hydrogeologic aspect of the study area, although many of the area’s hydrogeologic features are interrelated. For an integrated view of the hydrogeology of the Carbon–Stillwater area, the reader is referred to other maps and reports of Montana Ground Water Assessment Atlas 6.
Introduction This map portrays the shallow potentiometric surface of bedrock units in the Carbon–Stillwater MBMG Ground Water Characterization Program (GWCP) study area from 2001 to 2005. The potentiometric surface represents the altitude to which water will rise in wells. Generally, the potentiometric surface is a subdued representation of topography where the highest groundwater altitudes coincide with topographic highs and the lowest groundwater altitudes with topographic lows. Groundwater flows downgradient from potentiometric high altitudes to potentiometric low altitudes. Most water wells in the area are completed in bedrock aquifers or unconsolidated alluvium associated with the major drainages. Residents of Carbon and Stillwater counties rely heavily on shallow groundwater for domestic use; 90 percent of wells are completed within 200 ft of the land surface and approximately 97 percent are completed within 400 ft of land surface. This area is within the Rocky Mountain and Northern Great Plains physiographic provinces and split by the Yellowstone River. The southern part is bounded by the Beartooth Mountain Front (the Front), the Big Horn Basin, and the Pryor Mountains. North of the Yellowstone River is the internally drained Lake Basin subarea. The Yellowstone River and its tributaries—Clarks Fork of the Yellowstone, Red Lodge Creek, Rock Creek, Rosebud Creek, and the Stillwater River—have incised into bedrock and deposit alluvium in their valley bottoms. Cold winters and hot summers characterize the climate; typically, April, May, and June are the wettest months. During this study, the popula-tion of Carbon and Stillwater counties was 9,921 and 9,481, respectively. Cities and towns (from largest in population to smallest) in Carbon and Stillwater counties are Red Lodge, Columbus, Bridger, Joliet, and Fromberg (Montana Depart-ment of Commerce, 2013).
Map Construction The potentiometric surface was mapped by contouring measured water-level altitudes collected by Montana Bureau of Mines and Geology researchers. Water-level measurements were obtained from: (1) the GWCP Carbon-Stillwater study and (2) the MBMG 319 study of the Lake Basin subarea between June 2001 and November 2005 (Carstarphen and others, 2007). Most wells inventoried were less than 200 ft deep; however, some were as deep as 400 ft. Supplemental water-level data from previous investigations were used where they provide additional detail; driller-reported water levels were used where measured data were sparse. Driller-reported water-level data were obtained from the Ground Water Information Center (GWIC). Additionally, GWIC land-surface altitudes of spring sites were used to construct the potentiometric surface. Solid black symbols represent inventoried wells with measured water levels, whereas hollow black circles repre-sent supplemental GWIC wells. Solid black circles with an asterisk following the water-level elevation represent inven-toried wells where a water-level measurement could not be obtained. In this case, the land-surface altitude and driller-reported water levels were used to estimate the water-level elevation. Inventory site locations were determined with handheld GPS units and are generally accurate to within 50 ft. Land-surface altitudes at inventoried wells were inter-preted from U.S. Geological Survey 1:24,000 topographic maps and are generally accurate to 10 ft (20 ft contour inter-val). Water-level measurements were made using electric or steel tapes; the accuracy of most measurements is 0.01 ft. Map contour accuracy is affected by data distribution, field measurement errors, accuracy of well locations, and errors in interpretation. The groundwater altitude portrayed here is expected to be accurate within one-half the contour interval (50 ft). County and township boundaries, major streams and roads, population centers, and major irrigation ditches were obtained from the Natural Resources Information System (NRIS) at http://nris.mt.gov. Surface geology was obtained from Berg and others (1999), Lopez (2000a, 2000b, 2000c, 2001, 2005), and Wilde and Porter (2000, 2001). USGS topographic maps were obtained from NRIS. Map construction was completed by hand-contouring water levels from primary and supplemental datasets. Where the density of inventoried wells is high (i.e., within Red Lodge city limits), some data symbols were eliminated to improve map readability. Water-level data used to complete this map are available from the MBMG Ground Water Information Center.
Geology The Yellowstone River flows west to east, splitting the map area into two geologic settings. South of the Yellow-stone River the area is structurally complex and contains the Beartooth Mountain Front, faults of the Nye-Bowler Linea-ment, the Fromberg Fault Zone, and the axis of the Reed Point Syncline (fig. 1). The bedrock units exposed near the Front range in age from Tertiary to Cambrian. Tertiary to Upper Cretaceous rocks generally dip southwest towards the Front, while Lower Cretaceous through Cambrian rocks are near vertical along the Front. In places, terrace gravel flanks the Front and alluvium exists in the modern floodplains (Lopez, 2000a, b, c, 2001, 2005). Terrace gravel along drainages south of the Yellowstone River represent changes of stage and drainage patterns resulting from uplift. The thickest terrace gravels are near Red Lodge and form prominent benches above Rock Creek. Ritter (1967) and Darlinton (1969) have extensively studied the terrace gravel near Red Lodge and along the northern flank of the Front. Generally, bedrock units north of the Yellowstone River are flat-lying, less faulted, and not as structurally com-plex compared to those in the south (fig. 1). The Lake Basin subarea is a prominent internally drained depression (Reiten and others, in prep.) containing Quaternary stream and lake deposits. The topographic depression forming the Lake Basin appears to be associated with the Lake Basin Fault Zone. Alluvium is also found in modern floodplains of tributary streams to the Yellowstone River; however, it is not as thick as alluvium south of and along the Yellowstone River. The Tertiary Fort Union Formation is exposed over much of the southern map area and consists of consolidated sandstone, shales, clays, and some coal. Tertiary and Cretaceous intrusive rocks, and the Sliderock Mountain Volca-nics, also crop out exclusively south of the Yellowstone River near the upper reaches of Stillwater River and Fishtail Creek. Upper Cretaceous rocks alternate between shale and sandstone formations, while Lower Cretaceous rocks consist of shales and siltstones of the Colorado Group. Unconsolidated Quaternary terrace gravel and graded fluvial sand and gravel (alluvium) occur in and surrounding the floodplains of major drainages. The geologic setting and hydrogeologic framework of the Carbon-Stillwater study area is described in detail in MBMG Ground Water Assess-ment Atlas 6, Map 2 (in prep.).
Hydrogeology This plate represents a regional shallow potentiometric surface based on data observed in aquifers and aquitards (confining units); undoubtedly, local variations exist. Detailed hydrogeologic studies have been completed in the area investigating topics such as surface-water/groundwater interactions near municipal water supplies (Rose, 2000, 2000a), groundwater chemistry along the Clarks Fork River (Levings, 1986), and groundwater quantity in Stillwater and Rosebud watersheds (Kuzara and others, 2012). Figure 2 shows the location and areal extent of the previous investigations.Groundwater is an important source for domestic, stock, and municipal use in the study area. The bedrock aquifer system contains alternating aquifers and aquitards. Groundwater can be obtained from the bedrock units throughout the study area. However, bedrock locations near alluvial valleys or irrigated lands provide better yields than do locations away from irrigation or surface-water influences. Wells located in upland island areas topographically separated from the Front gener-ally yield less; groundwater contours in these areas are drawn as approximate (i.e. T. 5 S., R. 19 E. or T. 4 S., R. 20 E.).
Shallow Groundwater Altitude in Bedrock Units of the Carbon–Stillwater Study, Carbon and Stillwater Counties, Montanaby
Daniel D. Blythe and Jon C. Reiten
Nye
Rapelje
Columbus
Red Lodge
Park City
Joliet
Belfry
WyomingMontana
Absarokee
Fromberg
