Montana Ground-Water Assessment Atlas No. 2, Part B, Map 5 December 2004

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

Dissolved-Constituents Map of the Southern Part of the Flathead Lake Area, Lake, Sanders, and Missoula Counties, Montana by John I. LaFave

Note - this map was originally published at a scale of 1:100,000 but the page sizes have been modified to fit the size of the paper in your printer. A full sized 36” X 48” 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 Web Address: www.mbmg.mtech.edu Montana Bureau of Mines and Geology A Department of Montana Tech of The University of Montana

R 24W R 23WLake County R 22W R 21W

. s e R rt 30’ 114 a b b u H Lake Mary Ronan Dayton Valley T 25N (3701 ft.)

Reservation Boundary D a y to n Flathead County C r. Sanders County

T 24N

Flathead County Lake County Montana Ground Water Assessment Atlas No. 2, Part B, Map 5 December 2004

R 17W R 20W R 19W R 18W F la th S e L a w a d k C e o a C u

114 00’ 114 n o n u t n y L ty a ( 3 k 0 6 e 7 f Swan t .) T 25N

Reservation Boundary

Range

T 24N Reservation Boundary Flathead Lake Swan Valley (2892 ft.)

S

w

a

n

R i v e r 47 45’ T 23N Little Bitterroot Valley

L i t t l e

B i t t S e r r o a o t l

R i iv s

e C r h

a

b

i n

T 22N e t Wild Horse Hot Springs

M

Hot Springs o u ls il Lake County n H Sanders County M t a w ie o i V n

u y s e ll n a T 21N V t L a i tt le i B n it te r r s o er o iv t R R iv e r

Camas Prairie Basin

d a e Lower C h Res 47 30’ t a l F 47 45’ T 23N

Polson

Moraine Polson T 22N Mission

Pablo Res. (3210 ft.)

R 17W Mission Valley R 18W

Flathead Lake Area Map Area Pablo Explanation k e re C Dissolved-constituent concentrations in milligrams per liter (mg/L) Circles represent wells completed in alluvium. T 21N less than 300 mg/L between 300 and 500 mg/L greater than 500 mg/L Ground-Water Characterization Program Study Areas d u Squares represent wells completed in bedrock (Belt Supergroup). M less than 300 mg/L between 300 and 500 mg/L greater than 500 mg/L Township boundary Section boundary Ronan Major road Range Secondary road Flathead Indian Reservation boundary Crow C s. r 47 30’ ow County boundary

k Stream ree C T 20N Federal/Tribal/State lands T 20N

C a m a s

C ls re l e i k H

e s e i o

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T 19N

Mis sion

Fla the ad T 18N

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R 23W 30’ 114 R 24W R 22W J oc ko Dissolved-Constituents Map primary openings through which water located in the Little Bitterroot valley, is Nuisance levels of iron and manganese are Montana Bureau of Mines and Geology, Smith, Larry N., 2002a, Geologic moves in the rocks are fractures or greater than that of the other valleys, with common throughout the mapped area. Iron Montana Tech of The University of framework of the southern part of the of the Southern Part of the "cracks") to yield water to wells and is a median of 398 mg/L. The median and manganese are essential to plants and Montana, Butte, Montana. Flathead Lake Area, Lake, Sanders, and Flathead Lake Area, Lake, included as part of the basin-fill aquifers dissolved constituent concentration in the animals, but may cause unpleasant taste, Missoula Counties, Montana: Montana R Sanders, and Missoula because it appears, based on the other valleys, with the exception of the odor, and staining of plumbing fixtures. REFERENCES Bureau of Mines and Geology Ground- iv potentiometric surface(s), to be in hydraulic Dayton valley, is less than 350 mg/L (figure The primary source of iron and manganese Abdo, G., 1997, Reappraisal of Water Assessment Atlas 2, part B, map er Counties, Montana communication with the basin-fill deposits. 1). in ground water is dissolution of minerals hydrogeology of the Little Bitterroot 10, scale 1:100,000. It should be noted, that ground water in in the bedrock. Iron concentrations in well Valley, northwestern Montana: Montana by the Belt bedrock occupies and moves GROUND-WATER QUALITY water may also be elevated (increased) by Bureau of Mines and Geology Open Smith, Larry N., 2002b, Thickness of through fractures and voids within the Recent and historic chemical analyses of corrosion of iron well casings and from File Report 350, 43 p. shallow alluvium, Flathead Lake Area, John I. LaFave rock, rather than through intergranular ground water from 242 wells were bacterial activity in and around the well Flathead, Lake, Sanders, and Missoula spaces as in the sand and gravel deposits. reviewed to assess background water screen. The secondary level of 0.3 mg/L Boettcher, A.J., 1982, Ground-water Counties, Montana: Montana Bureau R 21W Author's Note: This map is part of the Because of the irregular distribution and quality in the mapped area. The results for iron was exceeded in 30 samples, and resources in the central part of the of Mines and Geology Ground-Water Montana Bureau of Mines and Geology orientation of the fractures, ground-water show that the ground-water quality is fairly 42 samples had manganese concentrations Flathead Indian Reservation, Assessment Atlas 2, part B, map 11, (MBMG) Ground-Water Assessment Atlas occurrence in the bedrock can be uniform in the basin-fill aquifers (with the above the secondary level of 0.05 mg/L. northwestern Montana: Montana Bureau scale 1:100,000. for the Flathead Lake Area ground-water unpredictable, and yields from bedrock exception of the Lone Pine aquifer in the of Mines and Geology Memoir 48, 28 characterization. It is intended to stand wells can vary widely between locations. Little Bitterroot valley). The most common The sodium adsorption ratio (SAR) p. Thompson, W.R., 1988, Hydrogeology of alone and describe a single hydrogeologic ions are calcium, magnesium and describes the suitability of water for the Jocko Valley, west-central Montana: aspect of the study area, although many In most of the valleys, the potentiometric bicarbonate; there is little sodium, sulfate, irrigation. SAR values below 10 are Briar, D.W., Lawlor, S.M., Stone, M. A. M.S. thesis, University of Montana, of the area's hydrogeologic features are surface generally reflects the surface or chloride (figure 2). Ground water from desirable for irrigation waters. The results J., Parliman, D. J., Schaefer, J. L., and Missoula, 82 p. interrelated. For an integrated view of the topography, and ground-water flow is away the Lone Pine aquifer is chemically distinct from the 120 samples analyzed as part of Eloise Kendy, 1996, Ground-water hydrogeology of the Flathead Lake Area from the mountains along the valley from the other valley-fill aquifers, with this study suggest that water from the levels in Intermontane basins of the Tuck, L.K., Briar, D.W., and Clark, D.W., the reader is referred to Part A (descriptive margins toward the streams that drain the relatively higher concentrations of valley-fill aquifers is well suited for northern Rocky Mountains, Montana 1996, Geologic history and overview) and other Part B maps of the valleys (LaFave, 2002). The ground-water dissolved constituents (figure 1), sodium irrigation. Other than samples from the and Idaho: U.S. Geological Survey hydrogeologic units of intermontane Montana Ground-Water Assessment Atlas flow systems in the valleys are strongly and bicarbonate, and lower concentrations Little Bitterroot Valley, SAR values did Hydrologic Atlas HA-738-B, scale basins of the northern Rocky Mountains, No. 2. controlled by topography and the of calcium and magnesium (figure 2). not exceed 3, indicating that the potential 1:750,000. Montana and Idaho: U.S. Geological distribution of permeable layers within the There is no discernable difference in sodium hazard is low. Only samples from Survey Hydrologic Investigations Atlas INTRODUCTION basin-fill deposits. chemical composition between ground the Lone Pine aquifer in the vicinity if Hot Donovan, J. J., 1985, Hydrogeology and HA- 738-A, scale 1:750,000. Calcium (Ca) + This map presents the distribution of water from wells completed in the alluvium Springs and Wild Horse Hot Springs had geothermal resources of the Little dissolved constituents in the major basin- SAMPLE SITES AND WATER and from wells completed in the Belt SAR values greater than 10, suggesting Bitterroot Valley, northwestern fill aquifers in the southern part of the QUALITY DATA bedrock that surrounds the valley (figure that ground water impacted by geothermal Montana: Montana Bureau of Mines Flathead Lake Ground-Water Three sets of dissolved constituents data 2). systems may not be suitable for irrigation. and Geology Memoir 58, 60 p. + Chloride (Cl) Characterization Study Area The area is are presented on the map: laboratory ) M T 20N Federal/Tribal/State lands Scale 1:100,000 Other lands UTM Projection Zone 11 NAD27 2 0 2 4 6 Miles

Kicking Horse Res. (3062 ft.) Mission Valley ground-water temperatures

Ninepipe Res.

(3 0 1 0 ft .)

M cD ona ld L ake (3 596 ft.)

T 19N

ek re C

C st reek Po

M is si on St. Ignatius es. n R sio Mis T 18N

C re ek

100%

Calcium (Ca) and Magnesium (Mg)

Figure 3. In the Mission Valley, ground-water temperatures are cool near the front of 47 15’ the Mission Range; temperatures generally increase down the ground-water flow path.

800 14 Sulfate(SO4) and Chloride (Cl) 114 00’ 114 T 17N 600 12 Dissolved constituents < 300mg/L

400 10 0% 0% Between 300 and 500 mg/L mg/L

Temp C Temp solved constituents > 500 mg/L O3) J is C

Characterization Study Area. The area is are presented on the map: laboratory ) M characterized by a series of north-northwest analyses obtained as part of this study and In the Mission Valley, temperature and Nitrate (NO3) is an essential nutrient for Hem, John D., 1992, Study and agnesium (Mg) trending, structurally controlled a recent study by Abdo (1997), laboratory chemistry of the ground-water evolve along plant life, yet is potentially toxic to humans interpretation of the natural chemical intermontane basins that are bounded by analyses from earlier studies, and values flow path. Ground water generally flows (especially infants) when present in characteristics of natural water: U.S. mountains formed mostly of estimated from field data. Water from 120 from the Mission Mountains on the east drinking water at excessive concentrations. Geological Survey Water- Supply Paper metamorphosed sedimentary rocks of the domestic, stock, public supply and monitor to the Flathead River which bounds the High levels of nitrate in well water typically 2254, 263 p. Sulfate (SO4 Proterozoic Belt Supergroup (bedrock). wells was analyzed for major ions and valley on the west (LaFave, 2002). indicate seepage from septic tanks, The basins are filled with consolidated to trace metals between May 1993 and Measurements of ground-water fertilizers, land application of animal wastes Kendy, Eloise and Tresh, Ruth E., 1996, unconsolidated Tertiary and Quaternary November 1996. Field measurements of temperature show a wedge of cooler water or other nonpoint sources. None of the Geographic, geologic, and hydrologic Swan Valley n = 9 sediment; most of the upper and surficial specific conductance, pH and water (less than 11 degrees C) along the flanks sampled wells had nitrate concentrations summaries of intermontane basins of Jocko Valley n = 22 basin-fill deposits are of glacial or glacial- temperature also were obtained from each of the Mission front where water enters above the health standard of 10 milligrams the northern Rocky Mountains, lake origin. Overviews of the area's geology of the sampled wells. To ensure collection the ground-water flow system, whereas per liter-nitrogen (mg/L-N); the highest Montana: U.S. Geological Survey Water Alluvial wells (all) n =155 are presented in Smith (2002a, 2002b), of a representative sample, each well was ground- water temperatures downgradient, concentration detected was 5.1 mg/L-N. Resources Investigations Report 96- Mission Valley n = 91 and Tuck and others (1996). The pumped prior to sample collection until near the discharge area along the Flathead In general nitrate was not detected in the 4025, 233 p. hydrogeology of various parts of the study the field parameters stabilized and at least River, are generally greater than 13 C valley-fill aquifers at concentrations greater Camas Prairie n = 10 area are presented in Kendy and Tresch three well-casing volumes were removed. (figure 3). The increase in ground-water than 1.5 mg/L-N; only ten samples had LaFave, John, I., 2002, Potentiometric Sodium (Na) + Potassium (K) (1996), Briar and others (1996), Slagle Analyses were performed by the Montana temperature along flow path coincides with nitrate concentrations between 1.5 and 5.1 surface map of the southern part of the Bedrock wells (all) n = 50 (1988), Makepeace (1994), Donovan Bureau of Mines and Geology's (MBMG) an increase in dissolved constituents. Near mg/L-N suggesting little impact from Flathead Lake Area, Lake, Sanders, and (1985), Boettcher (1982), Thompson Analytical Laboratory. An additional 122 the Mission front concentrations are surface sources of nitrate to the basin-fill Missoula Counties, Montana: Montana (1988) and Abdo (1997). The Flathead ground-water samples collected by the generally less than 300 mg/L; aquifers in the mapped area. Bureau of Mines and Geology Ground- River and its tributaries drain the valleys MBMG or the U.S. Geological Survey downgradient, near the Flathead River, Water Assessment Atlas 2, part B, map in the mapped area. Ground water in the prior to 1993 were also used. The concentrations are generally greater than MAP CONSTRUCTION 4, scale 1:100,000. Lone Pine wells n = 76 basin-fill sediment and the fractured laboratory data were supplemented by 500 mg/L (figure 4). The chemical This map was constructed by plotting bedrock along the valley margins is an dissolved-constituents concentrations composition of the ground water changes "low," "intermediate" and "high" Makepeace, S. V., 1994, Hydrogeologic important source of municipal, domestic, estimated from field measurements of as well. The cooler water with lower concentrations of dissolved constituents framework for principal valley fill irrigation, and stockwater. specific conductance at an additional 346 dissolved-constituent concentrations near of 242 ground-water samples. The aquifers: Flathead Indian Reservation, wells. The laboratory analyses and field the Mission front is a calcium-magnesium- laboratory data were supplemented by Montana, CSKT Natural Resources Bicarbonate (HCO3) and Carbonate (CO3) Aquifers are saturated geologic materials measurements presented on this map are bicarbonate type water; as the water estimates of dissolved- constituent Department, 13 p. that yield sufficient water to supply wells available from the Montana Ground-Water becomes warmer and the dissolved concentrations derived from specific- - Ca-Mg-HCO3 and springs. Non-aquifer materials (also Information Center database. constituents increase, the water becomes conductance measurements made at an Slagle, S. E., 1988, Geohydrology of the type water known as confining beds) also may be more enriched in sodium and bicarbonate additional 346 wells. The specific- Flathead Indian Reservation, saturated, but have low permeability and DISSOLVED CONSTITUENTS (figure 5). conductance (SC) measurements were used northwestern Montana: U.S. Geological n = number of samples do not produce usable amounts of water Water quality may be characterized by the to estimate dissolved constituents (DC) Survey Water- Resources Investigation to wells or springs. Within the basin-fill type and concentrations of its dissolved MAJOR IONS AND SUITABILITY FOR according to the equation: DC = A x SC Report 88-4142, 152 p. Figure 2. Ground water across the mapped area is predominately a deposits, permeable layers of sand and constituents. The dissolved-constituents WATER USE (Hem, 1992). Based on a straight-line calcium-magnesium-bicarbonate type, except for water from the gravel form the aquifers and are composed value is the sum of the major cations (Na, Table 1 summarizes the results of the 120 regression of data from the mapped area, Lone Pine aquifer which has a distinct sodium-bicarbonate signature. of alluvium (silt, sand, and gravel most Ca, K, Mg, Mn, Fe) and anions (HCO3, ground-water analyses performed for this a value of A = 0.92 was used in the above likely deposited by glacial meltwater CO3, SO4, Cl, SiO3, NO3, F) expressed study and from Abdo (1997). For reference, equation. streams). These permeable layers are in milligrams per liter (mg/L). To highlight the U. S. Environmental Protection typically covered and/or interfinger with areal patterns of dissolved constituents Agency's recommended maximum ACKNOWLEDGMENTS glacial till (poorly sorted clayey gravel within the aquifer the concentrations are contaminant levels (MCL) and secondary Well owners who granted access and 800 Percentiles deposited directly by glaciers), and glacial- presented in three categories. Values less maximum contaminant levels (SMCL) for personnel from the Confederated Salish 95th lake deposits (clay and silt deposited in than 300 mg/L are plotted in blue symbols; public water supplies are also presented. and Kootenai Tribes who assisted with the glacial lakes); their depth, continuity, and those between 300 and 500 mg/L are in Constituents for which maximum levels data collection are gratefully 700 character vary from valley to valley green; and those greater than 500 mg/L have been set may pose a health threat at acknowledged. Reviews of this report by 75th reflecting the variable depositional history are in orange. elevated concentrations. Secondary levels Tom Patton, and Wayne Van Voast 600 of each valley. The basin-fill aquifers can are set for aesthetic reasons--elevated improved its clarity. 50th be unconfined, semi-confined, or fully Dissolved constituents in ground water are concentrations of these constituents may confined. Shallow alluvium along rivers a result of the initial chemistry of the be a nuisance (bad taste or odor, or staining) SOURCES OF DATA and streams typically contains unconfined recharge water and subsequent interactions but do not normally pose a health risk. Geographic Features: 500 25th aquifers, whereas the deeper aquifers that of that water with soils and aquifer Population centers and roads are from are capped by till or glacial-lake deposits materials. Their total concentration Ground water in the basin-fill aquifers is 1:100,000-scale U.S. Geological Survey 5th are typically semi- to fully confined. provides a general indicator of water suitable for domestic and stock (USGS) Digital Line Graph files available 400 Although the permeable layers within the quality; the lower the total, the better the consumption as well as for irrigation. In from the Natural Resources Information basin-fill deposits may not be contiguous water quality. Typically, water does not the 120 samples, only fluoride (23 System (NRIS) at the Montana State over large areas, they generally have become too salty to drink until the samples), arsenic (8 samples), and barium Library, Helena, Montana. Hydrography 300 sufficient hydraulic continuity to be concentration of dissolved constituents (3 samples) were detected above their has been simplified from the 1:100,000 considered a single entity in terms of reaches about 2,000 mg/L. All of the respective health standards (table 1). All Digital Line Graph files. Township ground-water flow on a valley-wide scale ground water in the basin-fill aquifers in of the fluoride and barium and most of the boundaries are from U.S. Forest Service. 200 (Slagle, 1988; LaFave, 2002). One notable the mapped area was well below this arsenic (5 out of 8) exceedences occurred The land ownership base was modified exception is located in the Little Bitterroot threshold; in general, the water is of good in the Little Bitterroot valley; most were from 1:100,000-scale land ownership data valley where a 7 to 60 foot- thick layer of quality for drinking and other uses. Based from wells in the vicinity of the Wild Horse available from NRIS. Dissolved Constituents mg/L 100 Pleistocene sand and gravel forms an on the 588 ground-water measurements Hot Springs geothermal area (also referred aquifer that underlies most of the valley. used in this study, dissolved-constituent to as the Camp Aqua geothermal area). Point Data: The aquifer, known informally as the Lone 0 concentrations averaged 357 mg/L. Ground Solute concentrations of geothermal water Well-location and water-quality samples Mission Valley Little Little Swan Valley Jocko Valley Dayton Valley Camas Prairie Pine aquifer (Donovan, 1985), is confined water from wells completed in the bedrock are commonly higher than those of were obtained by the Ground-Water (n = 246) Bitterroot Bitterroot (n = 24) (n = 64) (n = 13) (n = 15) by as much as 350 feet of silt and clay that (374 samples, average = 357 mg/L) was nonthermal waters (Hem, 1992). Abdo Characterization Program and personnel alluvium & Lone Pine separates it hydraulically from shallow slightly higher in dissolved constituents (1997), Donovan (1985) and Kendy and from the Confederated Salish and Kootenai bedrock (n = 72) alluvial aquifers along the Little Bitterroot than wells completed in the alluvium (146 Tresh (1996) all report higher Tribes. Well locations are accurate to the (n = 45) River and the valley margins. samples, average = 345 mg/L); the concentrations of dissolved solids in the 2.5-acre level (to within +/- about 300 difference however (less than 5 percent), geothermal areas of the Little Bitterroot feet). All water-quality data used on this Figure 1. Dissolved constituents in ground water are generally less than 500 mg/L across the mapped area. However, The Belt Supergroup bedrock which occurs is not significant. In general, the dissolved- valley. map are available from the Ground-Water around the fringes of the valleys generally constituent concentration of ground water Information Center (internet: median concentrations from the Dayton valley and the Lone Pine aquifer in the Little Bitterroot valley are higher than has sufficient fracture permeability (the from the Lone Pine aquifer (Abdo, 1997), http://mbmggwic.mtech.edu) at the those in ground water from the other valleys. J is C o 200 8 D c Sodium (Na) and Potassium (K) k o 0 6 Jocko Valley 16 14 12 10 8 6 4 2 0 Miles from mission range

Temp Dissolved constituents

Bicarbonate (HCO3) and Carbonate ( Riv er Figure 4. The average dissolved constituent concentration and temperature of ground water in the Mission Valley increases with - individual analysis distance away (downgradient) from the Mission Range. Boxes represent averages. Arlee (Colors refer to general locations on figure 3.) 100% Figure 5. As the dissolved-constituent concentration increases, T 16N the ground-water chemistry evolves from a calcium-magnesium- bicarbonate type to more of a sodium-bicarbonate type water. Table 1. Summary of water-quality data for 120 wells sampled during this study and in the Little Bitterroot Valley by Abdo (1997). Sanders County Lake County Number Missoula County Common constituents Min Mean Median MaxSMCL MCL exceeding Dissolved constituents-sum (mg/L)* 120 347 352 657 ------Total dissolved solids (mg/L)** 84 234 236 429 500 -- 0 Sodium (mg/L) 0.7 40.5 21.8 156.0 250 -- 0 Potassium (mg/L) <0.1 1.6 1.4 6.5 ------Calcium (mg/L) 0.8 28.9 30.2 93.8 ------Magnesium (mg/L) <0.1 11.2 9.8 42.9 ------Chloride (mg/L) <0.5 6.6 2.6 93.8 250 -- 0 Bicarbonate (mg/L) 69.8 222.1 224.8 448.5 ------Sulfate (mg/L) <2.5 8.4 4.7 107.3 250 -- 0 Nitrate (mg/L as N) <0.25 0.5 <0.25 5.1 -- 10 0 Fluoride (mg/L) <1.0 1.5 <1.0 8.1 -- 4 23 Iron (mg/L) <0.003 0.4 0.02 5.6 0.3 -- 30 Manganese (mg/L) <0.002 0.2 0.01 4.3 0.05 -- 42 Selected trace elements T 15N Arsenic (ug/L) <1.0 10.5 1.1 169.0 -- 50 8 Barium (ug/L) <10.0 224.6 131.4 1675 -- 1000 3 Chromium (ug/L) <2.0 4.6 2.0 16.6 -- 100 0 Selenium (ug/L) <1.0 0.5 <1.0 6.4 -- 100 0 Number Other parameters Min Median MaxSMCL MCL exceeding Sodium adsorption ratio (SAR) 0 0.8 27 ------Hardness as CaCO3 56 207 401 ------pH 6.7 8.1 9.5 6.5 - 8.5 -- 6 '--', No standard available or not applicable. R 20W * Dissolved constituents is the sum of major cations (Na, Ca, K, Mg, Mn, Fe) R 19W and anions (HCO3, CO3, SO4, Cl, SiO3, NO3, F) in mg/L. ** Total dissolved solids reported as equivalent weight of evaporation residue. MCL - U.S. EPA maximun contaminant level for public water supplies. SMCL - Secondary contaminant level for public water supplies.