Montana Ground-Water Assessment Atlas No. 1, Part B, Map 4 October 1998 Revision 1 - Dec. 18, 1998

Montana Bureau of Mines and Geology A Department of Montana Tech of The University of Montana

Thickness of the Fox Hills—Lower Hell Creek Aquifer, Lower Yellowstone River Area: Dawson, Fallon, Prairie, Richland, and Wibaux Counties, Montana by Larry N. Smith

Note - this map was originally published at a scale of 1:250,000 but the page sizes have been modified to fit the size of the paper in your printer. A full sized 36” X 45” colored print of this map can be ordered from the Office of Publications and Sales of the Montana Bureau of Mines and Geology, 1300 West Park Street, Butte, MT 59701. Phone: 406-496-4167 E-mail: http://mbmgsun.mtech.edu Montana Bureau of Mines and Geology A Department of Montana Tech of The University of Montana

Explanation

> 0-100 feet 4 100-200 feet

200-300 feet

300-400 feet

400-500 feet

Well location showing aquifer thickness in feet:

322 Water well log

270 Geophysical log

Location of geophysical log examples 24N

County boundary 50E Township boundary

County seat 23N Major road

Principal stream

Area where the Pierre Shale is at or near the surface k e e

r Outcrop area of the Fox Hills Formation C 22N r te wa ed R

3 53E Montana Ground-Water Assessment Atlas No. 1, Part B, Map 4 55E 56E October 1998 M i s Revision 1 - Dec. 18, 1998 52E 54E s 105o o Poplar u r H i a Dome r 51E d s c 57E r a 255 b

b R C i l v 27N h a e 230 rl e ie r C 59E r 58E e e k 332 C r e 270 e 300 k o o 48 48 200 26N 295 230 268 26N 100 223 323

322 157 233 238 25N 25N 270 270 Eas t Re dwa te r 175 C reek 182

215

F ir st 243 283 H 24N a 200 y 218 C 275 282 276 re ek 279 277 270 272 287303 236 288 352 237 299 265 300 330 348 292 277 326 316 23N 288 217 295 304 Sun Beagle 357 367 Sidney 307 331 264 275 275 268 295 256 308 N 337 o 309 rt 300 h F 280 ork 300 22N Fox Cr eek Fox Cr ee k 250 267

No 387 rt h F ork 284 B 387 urn 3 00 21N RICHLAND

Ground-Water Characterization Study Areas 400

412

NORTH DAKOTA

M 20N

ONTANA DAWSON

PRAIRIE

WIBAUX 294 19N

322

FALLON

18N SOUTH 266 Lower Yellowstone River Study Area DAKOTA

300

17N

106o 45E 47E 48E 49E 50E N 16N 432

46E

400 Scale 1:250,000 15N 300 0 5 10 15 miles 491

Transverse Mercator Projection o 268 B 47 ra Central Meridian -105 Degrees c 300 k

1927 Horizontal Datum C e

ed t Thickness interval = 100 feet ar t

420

C r

14N C e 378 r e ee k k 400 389 ns 220 C r 21N e ek 394 276 383

Bur 290 300 ns 400 Cre T ek 293 268 h ir te en m 300 i 20N 245 le 300 234 212 C re e 226 k 310 211 292

331 313 19N S 383 mit h C ree 205 k 348

305

226 18N

300 U p p er S ev C en ottonw mil oo e Cree d 304 k Creek 382 237 17N 193 200 145 190 235 200 277 293 283 150 378 332 257 314 177 149 C 16N le ar

Glendive

C 400 140 400 re 153 ek K reek 300 rug C

200 G

l e n d 15N 170 i 411 ve 159 Cree 100 k 427

o Wibaux 47 122

320 14N 140 k 389 232 400 345 Andrau 1-29 NPRR 400

herr C y C reek 13N 479 334 45E 46E 347 106o 299

47E 48E R i v e r

12N 300 Terry 400

e

301 n to s w o 463 11N l l e Y

49E P o

w

d

e r

10N R

i

289 v

e r

50E 51E

Andrau 1-29 NPRR T. 14 N. R. 51 E. Sec. 29 Spontaneous Resistivity Potential

75

400 - Thickness of the Fox Hills—Lower Hell Creek Aquifer, Lower Yellowstone River Area: Dawson, Fallon, Prairie, Richland, and Wibaux Counties, Montana 500 - Formation Fort Union

by 600 - Larry N. Smith 60 200 60 C ed 300 ar C re ek 100

13N

400 391

Ca 100 bin C 200 r ee k 12N

403 O 448 ’Fa Cedar llo n C re 349 300 ek 371

400 100

314 11N 305

310 400

100 300

279 200 300 10N 55E 271 B ea 306 10N ver C re 400 ek 200 54E 262 418 300 52E 53E 9N 105o 9N 374 P enn el C re ek 55E mi San dsto ne C Sun / Beagle re e T. 23 N. R. 59 E. Sec. 17 431 k Creek Spontaneous Resistivity Potential 8N 385 8N

400 100

600 - 310 Formation

Fort Union 195

Pi Baker 700 - ne C reek 7N 327 7N

800 - A

700 - Introduction aquifer to calculate the thickness, using geographic information of 50 feet. It is estimated that the accuracy of the map is system software. The contours were evaluated and then between 50 and 100 feet in most of the areas, but in some redrawn by hand to fit most of the 170 data points of thickness areas with fewer control points the accuracy may be reduced. This map illustrates the thickness of the Fox Hills–lower and the outcrop areas of the Fox Hills Formation (Vuke-Foster 800 - Hell Creek aquifer in the Lower Yellowstone River Area. The et al. 1986; Colton et al. 1994; Wilde and Vuke 1994; top of the aquifer is at the top of a sandstone-dominated Bergantino and Wilde 1998a, b). Of the interpretations used sequence of sandstones (aquifer materials) and mudstones from geophysical logs, about 23% are from Feltis et al. (1981), Data Sources (non-aquifer materials) near the middle or base of the Hell 12% were reported by oil and gas companies, and the remaining Creek Formation (Figure 1, Smith and LaFave 1995). The were made for this study; a total of 9% of the data were from 900 - base of the aquifer is defined at the top of the Pierre Shale, water well logs. Contours fit most data points. Geographic features: which was picked from geophysical well logs at the uppermost Population center locations and roads are from 1:100,000- shale marker in the upper Pierre, below the sandstones or scale USGS digital line graph files available from the Natural siltstones of the overlying Fox Hills Formation (Smith 1995; Resources Information System (NRIS) at the Montana State 1000 - Smith and LaFave 1995). Sandstone beds in the Fox Hills Library, Helena, Montana. Hydrography has been simplified Formation are continuous across the study area, except where Map Use from the 1:100,000 digital line graph files. Township eroded near the Cedar Creek Anticline and the Poplar Dome. boundaries are from 1:250,000-scale USGS maps and are Hell Creek Formation aThis map can be used to estimate the thickness of the Fox available from NRIS. Geologic a a aThis report a Hydrologic Hills–lower Hell Creek aquifer at locations where new wells 1100 - units: units: may be drilled or where older wells may be deepened. Most Point data: a aa a a a a Terrace a a Shallow hydrologic water wells in the area penetrate less than 50% of the aquifer Water well drillers’ logs, well locations, and water-quality a a a Alluviuma unit aaa a a a a aaa Fort Union Formation aathickness, so increased well productivity may be obtained by data are stored in the Ground-Water Information Center data aaa a a a a a Deep hydrologic a a a a base at Montana Bureau of Mines and Geology (MBMG). aaa a a deepening a well and increasing the open interval to the total a a a a unit 1200 - aaa a a thickness of the aquifer. Geophysical logs and interpreted tops are stored at MBMG; aaa a a a a a Confining bed aaa a a a a Hell Creek a a The aquifer is more than 450 feet thick in parts of Fallon, logs are also in the files of the Montana Board of Oil and Gas Formation a Fox Hills– aaa a a Prairie, and Wibaux counties. Recent erosion near the Cedar Conservation in Billings, Montana. aaa a a a a a lower Fox Hills Hell Creek Formation aquifer Creek Anticline and the Poplar Dome and changes in thickness aaa a a 1300 - of sandstone units in the lower Hell Creek Formation and the Fox H Fox Hills Formation due to depositional and erosional patterns, Hell Cr About 11% of the water wells in the area are completed cause the aquifer to vary in thickness across the map. The References in the Fox Hills–lower Hell Creek aquifer. Many wells yield coincidence of aquifer thinning along the Cedar Creek Anticline large volumes of water compared with wells completed in and Poplar Dome indicates that less sediment was preserved 1400 -

the other bedrock aquifers in the area (aquifers in the Fort in these areas due to uplift on these structures relative to the Bergantino R. N. and Wilde, E. M. 1998a. The preliminary geologic Fox Hills Union Formation and upper parts of the Hell Creek Formation). surrounding areas. map of the Culbertson 30 x 60-min. quadrangle, eastern Montana Formation Well yields from the Fox Hills–lower Hell Creek aquifer are and adjacent North Dakota. Montana Bureau of Mines and Geology up to 400 gallons per minute (gpm), as reported on drillers’ Open-File Report 359. Scale 1:100,000. Bergantino R. N. and Wilde, E. M. 1998b. The preliminary geologic map logs; the median yield is 12 gpm. Water in the aquifer is of the Wolf Point 30 x 60-min. quadrangle, eastern Montana and 1500 - generally a sodium-bicarbonate type with dissolved constituents Map Accuracy adjacent North Dakota. Montana Bureau of Mines and Geology Shale ranging from 1,000 to 2,500 milligrams per liter (mg/L). Open-File Report 358. Scale 1:100,000. Pierre Colton, R. B., Vuke, S. M., and Fullerton, D. S. 1994. Preliminary geologic map of the Glendive 30 x 60-min. quadrangle. Montana Bureau of Map accuracy is affected by data availability, accuracy Mines and Geology Open-File Report 276. Scale 1:100,000. of well locations, errors in interpretation of log data, and Feltis, R. D., Lewis, B. D., Frasure, R. L., Rioux, R. P., Jauhola, C. A., Figure 1. Correlations betwe Methods of Map Construction smoothing during contouring. Well-log data are distributed and Hotchkiss, W. R. 1981. Selected geologic data from the northern drilled for oil and gas show ho unevenly across the map; accuracy is greater near the data great plains of Montana. U.S. Geological Survey Water-Resources Investigations Open-File Report 81-415. 63 p. thickness of the Fox Hills–low points shown. Water well locations are typically accurate to potential and resistivity boreh The thickness of the Fox Hills–lower Hell Creek aquifer within a 40-acre area; those visited by agency personnel are Smith, L. N. 1995. Structure contour map on the Upper Cretaceous Pierre (Bearpaw) Shale, east-central Montana. Montana Bureau of Mines interpret lithologies. The logs was mapped mostly from geophysical logs (primarily accurate to within a 2.5-acre area. Oil and gas well locations and Geology Open-File Report 333. Scale 1:250,000. spontaneous potential and resistivity) made in wells drilled water filled sandstone is repre are typically accurate to 10 feet. Smith, L. N., and LaFave, J. I. 1995. Hydrogeologic framework and sandstone, mudstone, or shale for oil and gas exploration and production (e.g., Figure 1) Inconsistency in determining the top of the aquifer is a ground-water resources of east-central Montana, in L. D. Hunter and and from a few drillers’ lithologic logs of water wells. Separate R. A. Schalla (eds.), Seventh International Williston Basin Symposium between the two curves for ea significant source of error, especially in areas of few data geologic and hydrologic units maps of the upper and lower surfaces of the aquifer were points, because the aquifer interfingers with non-aquifer Guidebook. Montana Geological Society, Billings. p. 429–443. combined with aquifer thickness data determined from 170 Vuke-Foster, S. M., Colton, R. B., Stickney, M. C., Wilde, E. M., Robocker, well logs and comparing well materials. Error in selecting the base of the aquifer is much J. E., and Christensen, K. C. 1986. Geology of the Baker and Wibaux The well logs show an abr well logs to produce the final map. Altitudes of the top and less than that in verifying the top because of the greater 30 x 60-min. quadrangles, eastern Montana and adjacent North base of the aquifer were hand contoured from 284 and 341 Pierre Shale to the sandstone- lithologic contrast between the Pierre Shale and the Fox Hills Dakota. Montana Bureau of Mines and Geology Geologic Map No. Shale or mudstone beds in the data points, respectively, inside the study area boundary and Formation. Correlation error and inconsistency in interpretation 41. Scale 1:100,000. additional data points from outside the boundary. The altitude Wilde, E. M., and Vuke, S. M. 1994. Preliminary geologic map of the or mudstone beds in the lower can be responsible for between 50 and 100 feet of difference but laterally discontinuous. Th maps were converted to grids of values, and then the altitude where the top of the aquifer is picked from logs. Contour Glendive 1 x 2-degree quadrangle. Montana Bureau of Mines and of the top was subtracted from the altitude of the base of the Geology Open-File Report 295. Scale 1:250,000. lower Hell Creek aquifer is pi smoothing may have introduced errors in depth on the order dominated interval, below a 10 interval. 800 A nticline 300

900 - 6N 6N 303 270

287 200 1000 -

352 100 O ’F a l 210 l o n 233 Hell Creek

Formation C r

Depth (Ft.)

1100 - e e

k 375 303 5N 5N 400 343 1200 -

56E 57E 55E 357 1300 -

ek e 4N 4N r 400 C eaver B 404 100 e l 1400 - t t i L Hills-lower 200 reek aquifer 58E

1500 - 300 Fox Hills Formation 3N 3N o 46o 235 46

400 1600 -

59E 60E 61E Shale Pierre een geophysical logs from two wells 2N 2N ow well logs were used to map the wer Hell Creek aquifer. Spontaneous hole logs are commonly used to are scaled so that porous, fresh- esented by wider areas, and clayey 61E 62E e are represented by narrower areas ach well. Contacts between different were chosen by comparing adjacent logs to mapped contacts. rupt change in lithology from the -dominated Fox Hills Formation. Author’s Note: This map is part of the Montana Bureau of Mines and Geology (MBMG) Ground-Water Assessment Atlas for e Fox Hills are generally thin. Shale the Lower Yellowstone River Area ground-water characterization. It is intended to stand alone and describe a single hydrogeologic Hell Creek Formation are common, aspect of the study area, although many of the area’s hydrogeologic features are interrelated. For an integrated view of the The upper contact of the Fox Hills – hydrogeology of the Lower Yellowstone River Area the reader is referred to Part A (descriptive overview) and Part B (maps) icked at the top of the sandstone- of the Montana Ground-Water Assessment Atlas No. 1. 00 – 300-ft-thick mudstone-dominated Geographic information system production by Joel Hall and Larry Smith. Digital cartography by Don Mason.