Montana Bureau of Mines and Geology Montana Ground-Water Assessment Atlas 7, Map 4 A Department of Montana Tech of The University of Montana March 2016

Benton Cascade-Teton T22N Lake 87 Ground-Water Characterization Area Muddy Creek R1E 15 R2E R3E Teton County R4E Burton Bench 89 R5E Teton River River T21N Vaughn LEGEND Missouri R River Great Falls Teton Sweetgrass Interstate highway 200 Sun Benton Qsf Qsc Rocky Mountains Rocky Deep Creek Choteau T20N Federal or State highway Ulm Lake Secondary roads Cascade County T22N Kcg Greenfields Bench Giant Springs T19N Streams Sun River Arch River 15 Smith Belt T22N Cities Great Falls T18N River 200 Muddy Creek Cascade Township lines Map Area 3301 Belt CreekBelt T17N Missouri River Belt Creek R2W R1W 3327 Static water-level measurements and value (ft), May–July 2012 Missouri A based on survey-grade GPS measuring point altitude

Adel MountainsCascade River Smith T16N QTsc 5430 Little Belt Mountains Static water level measured during field visit between 2005 and 2007 0102030405 R3W R2W 15 Miles 2394 T15N Well with multiple measurements and GWIC identification number Qsf Kcg T21N 89 Qsf 111°00'00" R2E R3E R4E R5E 89 Supplemental GWIC well (unmeasured, but typical water level) T14N R6E T21N Neihart Vaughn R6E ≥3400 87 Potentiometric surface contour showing line of equal water-level R1W R1E R7E <3400 altitude for the Madison Group aquifer. Figure 1. Index map showing principal cities, drainages, and physiographic locations in the Madison well Qsc Contour interval 100 ft and 5 ft. Dashed where inferred. Cascade–Teton Ground Water Characterization Program investigation. The potentiometric map 010205 Miles T13N covers the Madison Aquifer in Cascade County. Madison outcrop Qsc River Giant Missouri River R8E R3W Springs 2394 2526 112°00'00" Sun 3301 Figure 2. As of September 2012, the Ground Water Information Center (GWIC) database contained records for 968 3328 Qsc R7E Potentiometric Surface in the Madison wells completed in the Madison Aquifer in Cascade County. Most wells are located near Great Falls, Montana. 216851 3327 3320 47°30'00" 3305 3310 Qsf 3315 Group Aquifer, Cascade County, 3305 3329 200 3323 3325 Qsc 3310 3320 North-Central Montana Great 47°30'00" 3400 3315 T20N 3465 A Cross Section A—A' A' Falls 3306 by Kcg 3322 3306 Qsf 7200 3306 Kcg 3320 3321 T20N TKi 3308 3322 3324 6800 James P. Madison 3325 3321 3321 Qsc 6400 Kthb Kvt Kcg 3323 3321 B Belt Creek Author’s Note: This map is part of the Montana Bureau of Mines and Geology (MBMG) Groundwater Assessment 6000 Qsf 3321 3320 3321 Atlas for the Cascade–Teton Area groundwater characterization. It is intended to stand alone and describe a single 5600 149852 R8E

hydrogeologic aspect of the study area, although many of the area’s hydrogeologic features are interrelated. For an TKi 3324 Sand Sand Logging Creek Belt Creek 5200 Box Elder Creek Creek Tiger Ulm B' integrated view of the hydrogeology of the Cascade–Teton Area, the reader is referred to the other maps of Montana 3324 3324 TKi Little Muddy Creek 217818 3322 3325 4800

Groundwater Assessment Atlas 7. (http://mbmggwic.mtech.edu) 28054 3321 142661 3324 3323 3322 (ft) *Msu 3323 4400 Kk QTsc Little Belt Creek

Missouri River Sand Coulee Sand Coulee Sand Coulee 3322 3325

Introduction 4000 122947 Qsf 120973 3323 Sand Coulee Qsc Qsf Mmu 3323 3323 190899 The Madison Group aquifer (Madison Aquifer) is an important source of groundwater in Cascade Qsf 14560 3600 201968 T19N 145619

34604 3326 2247 County, north-central Montana (figs. 1, 2). Not only does it provide water for public supply, self-supplied Kcg 3200 Kcg Qsf T19N domestic, self-supplied industrial and livestock purposes, it is also the source of water for Giant Springs Kk 3322 Kk 3322 (map). 2800 Qsc Potentiometric surface Qsc 3322 Belt QTsc KJsu 3323 3323 3324 Giant Springs is located on the south bank of the Missouri River and is among the largest springs Kvt 2400 pre-Mmu 2315 in the United States (Meinzer, 1927). A discharge of 298 cubic feet per second (cfs;134,700 Mmu Coulee 2000 gallons/minute) was measured indirectly (USGS, 1974; Wilke, 1983), thus documenting it as the single 20,00040,000 60,000 80,000 100,000 120,000 140,000 160,000 180,000 200,000 220,000 Kcg Kk Qsf largest volume discharge point from any aquifer in Montana. Vertical exaggeration x19 (ft) Stockett 3324 As part of the MBMG Ground Water Characterization Program, a potentiometric-surface map for Qsf 3325 Box Elder Creek the Madison Aquifer was constructed. A potentiometric surface represents the altitude to which water will Figure 3. Geologic cross section from just north of Great Falls (A) to the Little Belt Mountains (A') showing geologic units including 3326 QTsc 3483 rise in wells penetrating an aquifer. The map provides a tool for evaluating groundwater flow directions the Madison Group. The Madison Group outcrops in the Little Belt Mountains and in Sand Coulee near Stockett. Kthb River and hydraulic gradients in the Madison Aquifer. Horizontal groundwater flow paths can be traced along 3325 Big Otter Creek lines drawn perpendicular to contours in a direction from high groundwater altitudes to low altitudes. 3325 15 Water-level trends were assessed using long-term hydrographs for several wells; water levels in one well 3329 3400 3700 have been measured since 1979. T18N Kk Kk Benton Kthb T22N Lake Smith 87 Kvt TKi Kcg Geographic Setting 3500 3800 15 200 T18N Cascade County lies in the transition between the Great Plains to the east and Rocky Mountains 3600 to the west, and contains topographic characteristics of both. The land surfaces in most of the county are T21N 89 Vaughn 3900 Qsf broad, gently sloping plateaus and terraces bordered by the Little Belt Mountains to the south and the Great Falls Missouri R 3327 Ming Coulee River 4000 Sun Adel Mountains to the southwest (fig. 1). The plains are underlain by north-dipping sedimentary rocks 200 Cascade consisting mostly of mudstone, shale, and sandstone. T20N 4100 The Little Belt Mountains, along the southeastern edge of Cascade County, are uplifted Ulm 3327 Missouri 4270 sedimentary rocks that dip northward about 15°–20° along the mountain front, but flatten north of the Kk 181868 3800 4200 T19N Bird Creek mountains to about 4° (fig. 3). The Madison Group is exposed in the Little Belt Mountains and where Belt Belt Creek 3400 drainages have incised through younger rocks such as near Stockett (see map). 4300 Smith Qsc 15 T17N 3700 3900 Cascade County is drained by the Missouri River, which exits the study area on the east side of T18N River Kk 3500 Kk Cascade 200 4400 4400 the county (map). Important tributaries include the Sun and the Smith Rivers, and Belt Creek (figs. 1, 2, 4110 Kk 4000 Qsc 4100 4, 6, and the map). Where they flow directly over outcrop areas in the Little Belt Mountains, the Smith River 4500 T17N Belt Creek River and Belt Creek are important recharge sources to the Madison Aquifer. River 3920 KJsu Missouri Kcg KJsu 3911 4200 4500 4600 Geologic Setting 3600 T17N T16N Qsf 4300 Qsc The geology of Cascade County has been mapped in detail (Vuke, 2000; Vuke and others, 2002a, R3W TKi R2W 4350 4700 b; Reynolds and Brandt, 2005, 2007); the geology presented here is generalized from those sources. 4600 Bedrock exposed in the Little Belt Mountains is pre-Cambrian metamorphic (gneiss and amphibolite), T15N 4800 igneous (diorite), sedimentary rocks, as well as Paleozoic sedimentary rocks; these rocks have been Kcg R3W 4678 combined as map unit pre-Mmu. The Madison Group (Mmu) and Paleozoic and Cretaceous igneous and 4503 4900 112°00'00" Kthb *Msu sedimentary rocks above the Madison Group, as map units *Msu, KJsu, Kk, Kcg, Kvt, Kthb, and TKi. < 500 ft R2E R3E R4E R5E 89 4678 T14N R6E 4700 4865 Map unit *Msu is missing in the subsurface throughout much of Cascade County because of pre-KJsu Neihart KJsu 28054 5000 501–1000 ft *Msu erosion (fig. 3). 4800 R1W R1E T16N 5100 1001–1500 ft 4852 The Mississippian Madison Group in Cascade County is a marine carbonate sequence composed R7E 4890 5010 of two formations: the upper formation is the Mission Canyon Limestone, and the lower formation is the 1501–2000 ft 010205 Miles T13N 4900 5200 Lodgepole Limestone. The Lodgepole Limestone consists of thin- to medium-bedded fossiliferous Kk 5000 5246 > 2000 ft KJsu Hound Creek 5100 dolomite, limestone, and shale (Weed, 1899). The Mission Canyon consists of alternating thin R8E Mmu Mmu 5271 Madison outcrop R2W Qsf Mmu 5269 T16N argillaceous dolomite beds and massive fossiliferous limestone (Peterson, 1966). The Mission Canyon 5200 was sub-aerially exposed as a low-relief landscape within which karst developed. Features associated with Map Units karst recognized in the Mission Canyon include enlarged joints, sinkholes, caves, and solution breccia Figure 4. The depth from land surface to the top of the Madison Group is less than 500 ft along the Sweetgrass Arch, but is 5300 Qsc Coarse-grained Quaternary sediment 5349 (Sando, 1974). Karst features occur in the upper 400 ft of the Madison Group, and are responsible for the greater than 2,000 ft along its east and west flanks. This map was produced by subtracting the altitude of the top of the Madison 5400 great yield of water to Giant Springs and some wells; below 400 ft, permeability is not influenced by karst Group (Smith, 2008) from the land-surface altitude. Qsf Qsf Fine-grained Quaternary sediment 5430 but restricted to normal fracture permeability. Total thickness of the Madison Group in Cascade County is Kcg Monarch R8E estimated to be about 1,000–1,500 ft (Weed, 1899; Witkind, 1971; Peterson, 1966, 1981; Noble and QTsc Coarse-grained Quaternary/Tertiary sediment others, 1982). TKi Mmu Benton KJsu *Msu The Sweet Grass Arch, a broad northwest-plunging anticlinal structure that trends northward from R5E TKi T22N Lake TKi Tertiary/Cretaceous igneous rocks the Little Belt Mountains, controls the depth below land surface of the Madison Group and other strata. 87 15 The top of the Madison Group is generally nearest land surface along the axis of the arch. This explains Qsf TKi Kthb Cretaceous Two Medicine, Horsethief, and Bearpaw-Horsethief transition unit T15N A' why many wells in Cascade County completed in the Madison Aquifer are within a few miles of the T21N 89 Vaughn arch’s axis and less than 500 ft deep. However, some wells on the flanks of the arch penetrate more than Missouri R Kk Qsf River Great Falls Kvt Cretaceous Virgelle and Telegraph Creek Formations T15N Qsc 1,000 ft of overlying Cretaceous rock to reach the top of the Madison Group (fig. 4). Qsc Mmu 200 Sun Mmu Qsc T15N T20N Qsf Mmu Kcg Cretaceous Colorado Group Map Construction Ulm TKi The potentiometric map was constructed by drawing equal-altitude contours based on 69 T19N Kk Cretaceous Kootenai Formation water-level altitudes measured in wells by the MBMG Ground Water Assessment Program (GWAP) Belt between 2005 and 2012 (most were measured May–July 2012). Measured water levels from other KJsu Pre-Kootenai Cretaceous through Jurassic sedimentary rocks, undivided *Msu Qsc projects (Duaime and others, 2004; Kuzara and others, in prep) were also used. All water-level data are 15 Smith (includes Morrison and Swift Formations) 47°00'00" Qsc T18N River available from the MBMG’s Ground Water Information Center (GWIC, http://mbmggwic.mtech.edu). Cascade 200 *Msu Pennsylvanian through post-Madison Mississippian sedimentary rocks, undivided R4E The potentiometric surface has a contour interval of 100 ft near the Little Belt Mountains and 5 ft near (includes Big Snowy Group, Amsden and Quadrant Formations) R2E R3E p re-Mmu 47°00'00" Great Falls. Typically, the representation of a regional-scale potentiomtric surface is not greatly T17N Belt Creek Mississippian Madison Group Kcg 111°00'00" River Mmu influenced by water-level data collected during multi-year periods because changes in altitudes are (includes Lodgepole and Mission Canyon Formations) TKi Missouri R6E 89 insignificant and/or the contour interval is such that even tens of feet of change may only slightly shift the pre-Mmu Pre-Madison Group sedimentary, igneous, and metamorphic rocks, undivided Qsc position of a contour. This is the case for areas of the Madison Aquifer with water-level altitudes above T16N TKi T14N about 3,400 ft above mean sea level (amsl). R3W R2W Kk T14N However, water-level altitudes in many Madison Aquifer wells were between 3,300 ft and 3,400 T14N ft amsl (map); the altitude in many wells was approximately 3,325 ft amsl as of May–July 2012. The T15N lowest water levels were within the cone of depression around Giant Springs. Because water-level *Msu altitudes measured in Madison Aquifer wells during the initial inventory between March 2005 and July R2E R3E R4E R5E 89 T14N R6E 0105 20 Miles 2008 (Carstarphen and others, 2011) could vary as much as 12 ft (figs. 6, 7), this could affect map Neihart Qsf Qsc Neihart accuracy in this area. To alleviate the time differences in water-level measurements, a subset of Madison Mmu R1W R1E wells inventoried during the initial part of the project was revisited in May–July 2012 and water levels in R7E the wells re-measured. unsaturated Madison at depth 010205 Miles T13N R1W R1E The land-surface altitude is used to calculate water-level altitude; this can influence the accuracy Madison outcrop R7E and interpretation of the potentiometric map. During the 2005–2008 inventory, land-surface altitudes at R8E well locations were interpreted from U.S. Geological Survey (USGS) 1:24,000 topographic maps and are generally accurate to 5 to 10 ft (based on 10- and 20-ft contour intervals). For most regional scale maps, Figure 5. The Madison Group is saturated with water in most places. Between the Little Belt Mountains and Great Falls, there is this level of accuracy is adequate. To alleviate the error associated with altitude determination using topo an area where the top of the water table is below the top of the Madison Group. Drillers’ logs for some wells in this area note maps, especially for 67 wells where water-level altitudes were less than 3,400 ft amsl, land-surface numerous unsaturated caverns. This map produced by subtracting the potentiometric surface altitude from the top of the Madison T13N Group altitude (Smith, 2008). altitudes were determined with a Leica Model 1200 survey-grade GPS accurate to within ±3 in. T13N Potentiometric Surface 3350 4525 The potentiometric surface shows that groundwater in the Madison Aquifer generally flows a a northward towards Great Falls and that a cone of depression has developed around Giant Springs where 3340 4520 flow lines converge on the springs. It’s reasonable to assume that the Madison Group outcrop receives GWIC ID 4515 diffuse recharge from rain and snowmelt that infiltrates through fractures and other openings. Probably 3330 28054 more significant is the large constant volume of water that leaks from the Smith River and Belt Creek 4510 3320 where these two streams flow across the Madison Group outcrop. Low-flow investigations on the Smith 4505 River show that it may be losing about 140 cfs and that Belt Creek may lose 14 cfs as they cross the 181868 3310 R8E Madison Group in the Little Belt Mountains (Kuzara and others, in prep). 217818 4500 REFERENCES 2247 3300 Fisher (1909) speculated that recharge to the Madison Aquifer and the source of Giant Springs 2315 4495 was underflow from the Missouri River into the buried pre-glacial Missouri River channel near the mouth 2394 Carstarphen, C.A., Smith, L.N., Mason, D.C., LaFave, J.I., and Richter, M.G., 2011, Data for water Reynolds, M.W., and Brandt, T.R., 2007, Geologic map of the White Sulphur Springs 30' x 60' 3290 4490 of Sand Coulee Creek (fig. 8); based on Darcy’s law, underflow through this area is calculated to be 120973 wells visited during the Cascade–Teton Groundwater Characterization Study: Montana quadrangle, west-central Montana: U.S. Geological Survey Open-File Report 132, scale approximately 2.3 cfs and does not explain Giant Springs’ discharge. 216851 4485 Bureau of Mines and Geology Open-File Groundwater Assessment Atlas 7 B-01, 1 sheet, 1:100,000. 3280 2526

Drillers’ logs for some wells completed in the Madison Aquifer describe caverns, voids, and Altitude (ft above mean sea level) scale 1:275,000. 4480 fractures in the upper part of the Madison Group consistent with karst development. In some areas, the 3270 3330 Sando, W.J., 1974, Ancient solution phenomena in the Madison Limestone (Mississippian) of caverns and voids are above the potentiometric surface, which can hinder drilling; wells 180017 and level) sea mean above (ft Altitude b Duaime, T.E., Sandau, K.L., Vuke, S.M., Hanson, J., Reddish, S., and Reiten, J.C., 2004, north-central Wyoming: U.S. Geological Survey Journal of Research, vol. 2, no. 2, p. 3260 186947 in T. 18 N., R. 4 E. are examples. Figure 5 shows areas where the potentiometric surface is below 3325 GWIC ID Reevaluation of the hydrological system in the vicinity of the Anaconda Mine at Belt, Cascade 133–141. the top of the Madison Group, leaving the upper part unsaturated. Voids in this part of the aquifer can 181868 County, Montana: Montana Bureau of Mines and Geology Open-File Report 504, 1 sheet, 116 p. 3250 make well drilling difficult. 3320 217818 Smith, L.N., 2008, Altitude of the top of the Madison Group, Cascade County, Montana: Montana Hydrographs (figs. 6, 7) for wells completed in the Madison Aquifer were analyzed for 3240 2247 Fisher, C.A., 1909, Geology and water resources of the Great Falls region, Montana: U.S. Geological Bureau of Mines and Geology Groundwater Assessment Atlas 7 B-03, 1 sheet, scale water-level trends. The hydrographs show that water levels increase during the summer months because 15 3315 2315 B Cross Section B–B' B' Survey Water-Supply Paper 221, 89 p. 1:75,000. b 2394 of recharge from precipitation and stream leakage; they decrease during the winter months when recharge 3500 Sand Coulee Qsf 10 3310 120973 is less. Besides seasonal variation, multiyear trends related to wet and dry climatic periods are apparent. drying climate Kuzara, S., Chandler, K., and Meredith, E., in preparation, Sustainable water supplies from the U.S. Geological Survey, 1974, Water resources data for Montana—Part 1, Surface water records 33550 33528 223850 33540 33534 3400 33533 During a dry cycle from 1995 to 2005, water levels dropped by about 30 ft; from 2005 to 2013, water 142234 Kk Madison Aquifer, central Montana: Montana Bureau of Mines and Geology. 1973: U.S. Geological Survey, Water Resources Division, Helena, Montana, 278 p. 5 Qsc levels recovered by a comparable amount (fig. 6). The hydrographs in figure 6a were also compared to 3305 3300 Kk KJsu Qsf the 12- and 24-month departures from normal precipitation, but the 36-month departure correlates the 0 3200 Lemke, R.W., and Maughan, E.K., 1977, Engineering geology of the city of Great Falls and vicinity, Vuke, S.M., 2000, Geologic map of the Great Falls South 30' x 60' quadrangle, central Montana: 3300 KJsu Potentiometric surface best. The comparison between the water levels and 36-month departure from normal precipitation shows ate 3100 Montana: U.S. Geological Survey Miscellaneous Investigations Map I-1025, scale 1:24,000. Montana Bureau of Mines and Geology Open-File Report 407, scale 1:100,000. m Qsc that long-term water levels are influenced more by 36-month precipitation anomalies than by any single -5 3295 3000 precipitation event. level) sea mean above (ft Altitude Meinzer, O.E., 1927, Large springs in the United States: U.S. Geological Survey Water-Supply Paper Vuke, S.M., Berg, R.B., Colton, R.B., and O’Brien, H.E., 2002a, Geologic map of the Belt 30' x 60' -10 Above 36-month average wetting cli 2900 The similarity in water-level responses indicates that the Madison Aquifer is highly 3290 Mmu 557, 94 p. quadrangle, central Montana: Montana Bureau of Mines and Geology Open-File Report 450, Below 36-month average interconnected (figs. 6a, 7b) in an area bounded by the 3,325-ft potentiometric contour. Wells 181868 and precipitation) of (in Departure 2800 16 p., 2 sheets, scale 1:100,000.

-15 Altitude (ft above mean sea level ) 2315 are located about 24 mi apart, yet water levels at both sites respond almost identically. Well 28054 3285 2700 Noble, R.A., Bergantino, R.N., Patton, T.W., Sholes, B.C., Daniel, F., and Scofield, J., 1982, (fig. 7a) is located near the Madison Group outcrop in the Little Belt Mountains and, although it shares 0 1000 2000 3000 4000 5000 6000 Thickness in feet of the Madison Group (TF331.60): Montana Bureau of Mines and Geology Vuke, S.M., Colton, R.B., and Fullerton, D.S., 2002b, Geologic map of the Great Falls North 30' x 60' Vertical exaggeration x 2.3 (ft) similar seasonal variations and increasing water-level trend with the wells in figure 7b, water levels in Jan-70 Jan-75 Jan-80 Jan-85 Jan-90 Jan-95 Jan-00 Jan-05 Jan-10 Jan-05 Jan-07 Jan-09 Jan-11 Jan-13 Open-File Report 99W-F, 1 sheet(s). quadrangle, central Montana: Montana Bureau of Mines and Geology Open-File Report 459, well 28054 respond differently than the wells completed in the highly connected zone of caverns, voids, 10 p., scale 1:100,000. and fractures bounded by the 3,325-ft amsl contour. Figure 6. (a) Hydrographs from six wells completed in the Madison Group show almost identical response to recharge and Figure 7. (a) Hydrograph for well 28054, which is located near the Madison Group Figure 8. Geologic cross section across Sand Coulee near Great Falls. The pre-glacial Missouri River cut a Peterson, J.A., 1966, Sedimentary history of the Sweetgrass Arch, in Billings Geological Society, climate; well pair 181868 and 2315 and well pair 2394 and 2315 are more than 24 mi apart. The response in the outcrop—the recharge zone—in the Little Belt Mountains for 2005 through 2012. channel into the top of the Madison Group. Glacial Lake Great Falls sediments and other alluvium filled this 17th Field Conference, Sweetgrass Arch, p. 112–34. Weed, W.H., 1899, Description of the Little Belt Mountains quadrangle, Montana: U.S. Geological Acknowledgements hydrographs indicates that the Madison group is highly interconnected (has high hydraulic conductivity) by the karst and Water level fluctuates seasonally by about 5–20 ft, and responds closely to ancestral channel. Assuming a hydraulic conductivity of 100 ft/day, a hydraulic gradient of 0.002, and a Survey Atlas Folio 56, 11 p. 2 This work was supported by the Ground Water Assessment Program at the MBMG. Well owners solution features that developed in the upper part of the Madison Group when it was subaerially exposed. Well 2526 is seasonal precipitation and long-term climatic trends (fig. 7b). cross-sectional flow area of 990,000 ft (3,300 ft x 300 ft), a maximum of about 2.3 cfs of groundwater may Peterson, J.A., 1981, Stratigraphy and sedimentary facies of the Madison Limestone and associated about 600 ft southwest of Giant Springs; it is completed in the Kootenai Formation with fractures that connect it to the (b) Expanded-scale plots for the same wells in figure 7a show similar but more move through the ancestral Missouri River channel, which is not enough flow to explain the discharge of Giant who allowed collection of the necessary data for the map, and the people who collected the data, are Madison Aquifer (T.W. Patton, Montana Bureau of Mines and Geology, oral commun., 2015), accounting for the difference subdued response to seasonal precipitation, reflecting the greater amount of Springs as speculated by Fisher (1909). rocks in parts of Montana, North Dakota, South Dakota, Wyoming, and Nebraska: U.S. Wilke, K.R., 1983, Appraisal of water quality in bedrock aquifers, northern Cascade County, gratefully acknowledged. Cartography assistance was provided by Susan Smith. The text, map, and in water levels between well 2526 and the other six wells. The drawdown is caused by discharge to the springs. storage in the part of the aquifer where these wells are completed. Geological Survey Professional Paper 1273-A. Montana: Montana Bureau of Mines and Geology Memoir 54, 22 p., 2 sheets. supporting figures were improved by reviewers including Russell Levens, Thomas Patton, John LaFave, (b) 36-month departure from normal precipitation (1895–2012) in Cascade County and Phyllis Hargrave. Edited by Susan Barth. (http://www.cefa.dri.edu/Westmap/Westmap_home.php). Water levels increase during wetting climates (2002–2012) and Reynolds, M.W., and Brandt, T.R., 2005, Geologic map of the Canyon Ferry Dam 30' x 60' Witkind, I.J., 1971, Geologic map of the Barker quadrangle, Judith Basin and Cascade counties, decline during drying climates (1995–2002). quadrangle, west-central Montana: U.S. Geological Survey Scientific Investigations Map Montana: U.S. Geological Survey Geologic Quadrangle Map GQ-898, scale 1:62,500. 2860, scale 1:100,000.