GWAA 07 Map 4.Ai
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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 broad, gently sloping plateaus and terraces bordered by the Little Belt Mountains to the south and the Great Falls Missouri R 3327 Qsf 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 The geology of Cascade County has been mapped in detail (Vuke, 2000; Vuke and others, 2002a, Qsc 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.