Map A. Well density per Map B. Well density per Map C...

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MarionSomers

Polson

Charlo

Bigfork

Whitefish

Kalispell

Swan Lake

Hot Springs

St Ignatius

West Glacier

Columbia Falls

Legend

LakesStreams

Cities or townsStudy areaCounty boundaries

Legend

Generalized geology

Statewide ground-watermonitoring network wellsWells visited during the Flathead Lake Ground-Water Characterization Study

Alluvium alongmajor drainagesGlacial depositsTertiary basin fill

Map F. Geographic and cultural features

Map G. Generalized geology, statewide monitoring wells, and wells visited duringthe Flathead LakeGround-Water Characterization Study

Legend

Map B. Well density per section in 1980

01 - 1011 - 30

31 - 5051 - 80

Number of well recordsper section:

NO OUTLINE

Map A. Well density per section in 1970

LegendNumber of well recordsper section:

NO OUTLINE 0

31 - 5051 - 80

LegendNumber of well recordsper section:

NO OUTLINE 0

1 - 1011 - 3031 - 5051 - 8081 - 160

NO OUTLINE 0

1 - 1011 - 3031 - 5051 - 8081 - 160

NO OUTLINE 0

1 - 1011 - 3031 - 5051 - 8081 - 160

51 - 8081 - 160

Legend

Number of well recordsper section:

Map C. Well density per section in 1990

Map D. Well density per section in 2000 Map E. Well density per

section in 2005

Map H. Distribution of alluvium, sections with over 50 wells (2005), and selectedhydrographs

FLATHEAD LAKE

HUNGRY HORSE RES.

North Fork Flathead R.

Middle Fork Flathead R.South Fork Flathead R.

Flathe

Stillwater R.

Whitefish R.

Swan R.

Flathe

Flathead R.

Jocko R.

Little Bitterroot R.

LAKEMCDONALD

WHITEFISH LAKE

ASHLEY LAKE

LITTLE BITTERROOT LAKE

SWAN LAKE

Montana Bureau of Mines and GeologyA Department of Montana Tech of The University of Montana

Ground-Water Open-File Report 19, Sheet 1 November, 2007

Sheet 1. The number of water wells per section in 1970, 1980, 1990, 2000, and 2005.

0 10 205Miles. . 0 10 205

Miles . 0 10 205Miles . 0 10 205

Miles . 0 10 205Miles

0 10 205Miles

The study area is defined by the Flathead Lake Ground-Water Characterization Area (LaFave and others, 2004). Maps A through E illustrate the number of water-well records per Public Land Survey System (PLSS) section in 10-year increments beginning in 1970 and include water-well records present in the GWIC database at the beginning of each stated year. Figure 1 (below) shows the progression graphically through 2005. While the number of PLSS sections with at least one well is increasing, the total number of wells is increasing at a much greater rate (note the separate scales in Figure 1). Throughout the map series, some PLSS sections that have small numbers of wells in non-valley locations result from in-correctly located wells in GWIC.Map F shows selected lakes, streams, cities, towns, and counties within the study area.Map G illustrates the general geology within the intermontane basins, locations of wells visited during the Flathead Lake Ground-Water Characterization Study, and the locations of statewide ground-water moni-toring wells. Comparison of the locations of visited and statewide monitoring network wells with the PLSSsection well densities shown on maps D and E shows that data from the visited wells and water-level records from the monitoring network are relevant to the most developed aquifers. These aquifers typically include large thicknesses of valley-fill aquifer materials. The alluvium shown on Map G includes largely surficial, generally unconsolidated sediments that are in relatively good hydrologic connection with surface water.Map H shows PLSS sections that contained more than 50 wells in 2005, the alluvial aquifers, and hydro-graphs from selected statewide monitoring wells. The hydrographs show ground-water storage or pressure change in some of the most used aquifers.

ReferencesLaFave, J.I., Smith, L.N., and Patton, T.W., 2004, Ground- water resources of the Flathead Lake Area: Flathead, Lake, and parts of Missoula and Sanders Counties: Part A- Descriptive overview: Montana Bureau of Mines and Geology Ground-Water Assessment Atlas 2A, 132 p.

Natural Resource Information System, Montana State Library, for base map coverages (http://nris.mt.gov/).

Explanation

Introduction

AcknowledgmentsThis report is primarily funded by a Montana Department of Natural Resources and Conservation grant obtained by the Clark Fork Basin Task Force, a voluntary citizen's group functioning as a consensus-based, collaborative watershed advisory committee.

These maps are based on data from the Montana Ground-Water Information Center (GWIC) database(http://mbmggwic.mtech.edu/), and display how ground water has been developed in the Flathead Lake Ground-Water Characterization Area. F L A T H E A D

L A K E

Alluvium

S A N D E R S

MISSOULAMajor highwaysTownship boundaries

Scale 1:792,000

Scale 1:792,000_̂

952 sections with at least one wellTotal number of wells in study area: 3,421

1,295 sections with at least one well

Total number of wells in study area: 6,894

1,486 sections with at least one wellTotal number of wells in studyarea: 10,296

SCALE 1:1,000,000 SCALE 1:1,000,000 SCALE 1:1,000,000 SCALE 1:1,000,000

1 - 1011 - 30

By Kirk B. Waren and Thomas W. Patton

Ground-Water Resource Development in the Flathead Lake Ground-Water Characterization Area, Flathead, Lake, Missoula, and Sanders Counties, Montana

SCALE 1:1,000,000

Cities or towns (see Map F)

Bedrock

As of 2005, 47 sections within the Flathead Lake Ground-Water Characterization Area had more than 50 wells. Of those, 43 sections intersected the alluvium. Eight of these sections are completely within the alluvium. Long-term water-level records from selected monitoring wells are shown in the inset graphs.

Well 85689T30N, R20W, Section 22, CDAC, Total Depth 308 ft.

1/1/1992 1/1/1996 1/1/2000 1/1/2004 1/1/2008DATE

Well 85628T30N, R20W, Section 20, DCCA, Total Depth 149 ft.

1/1/1992 1/1/1996 1/1/2000 1/1/2004 1/1/2008DATE

Well 148189T30N, R20W, Section 19, DAAC, Total Depth 342 ft.

1/1/1992 1/1/1996 1/1/2000 1/1/2004 1/1/2008DATE

Well 6419T28N, R21W, Section 4, DCDA Total Depth 23 ft.

1/1/1984 1/1/1988 1/1/1992 1/1/1996 1/1/2000 1/1/2004 1/1/2008DATE

Montana Ground-Water Information Center, Montana Bureau of Mines and Geology, Montana Tech of The University of Montana (http://mbmggwic.mtech.edu/).

5 Cities or towns (see Map F)

Figure 1. GWIC database records for wells within the Flathead Lake Ground-Water

Characterization Area

10,000

15,000

20,000

1960 1970 1980 1990 2000 201005001,0001,5002,0002,500

Total number of wellrecordsNumber of sectionswith at least one well

Well 131524T29N, R21W, Section 20, CCCC, Total Depth 278 ft.

1/1/1962 1/1/1970 1/1/1978 1/1/1986 1/1/1994 1/1/2002DATE

Map A. Well density per Map B. Well density per Map C...

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