Ground- Water in the Clark Fork Basin

Transcription

1 Well 19142: 6N 19W 7 BABC- Ravalli County Ground- Water in the Clark Fork Basin Tom Patton, John LaFave, and Larry Smith Montana Ground-Water Assessment September 27, 26 The Ground-Water Assessment Program at the Montana Bureau of Mines and Geology conducts aquifer characterizations for the state of Montana. To date the program has produced two atlases, 34 maps, and several open-file reports describing the hydrogeology of 14 Montana counties. The Assessment Program operates a long-term monitoring network of about 9 wells from which it collects water-level and water-quality data. Long-term water-level records are useful when impacts from climate, development or other factors must be evaluated. All data collected by the program is put into the Ground-Water Information Center (GWIC) database which in addition houses ground-water data for about 2, Montana wells. GWIC can be reached on the web at 1

2 Clark Fork Basin Kalispell Thompson Falls N 5 Mi Missoula Hamilton Butte The Montana portion of the Clark Fork basin covers about 21,459 square miles and extends from the river s head waters near Butte, Montana north along the Continental Divide to where the North Fork of the Flathead River enters the country from Canada. A portion of the basin extends northward from there into British Columbia Canada. The river leaves Montana below Noxon at its border with Idaho. Much of the basin consists of intermontane valleys that began developing during the Tertiary and that are connected by relatively narrow, incised canyons. 1

3 Geology N 5 Mi Alluvium Glacial Tertiary The intermontane valleys are filled with sediment generally derived from surrounding bedrock. The sediment has been transported into the basins by smaller streams tributary to major through-flowing branches of the Clark Fork. These sediments may occur as alluvial fans along the valley margins but are often fine grained and may not be aquifers. Alluvium is deposited along most streams and often contains the most prolific aquifers. A thick well-sorted gravel was deposited in the Kalispell Valley by the Flathead Lobe of the Cordilleran ice sheet. Glacial Lake Missoula and its outwash floods modified the surficial geology in the southern part of the Flathead drainage and downstream of Missoula, Montana. 2

4 Previous Work Kendy, E., and Tresch, R., 1996, Geographic, geologic, and hydrologic summaries of intermontane basins of the Northern Rocky Mountains, Montana, U.S. Geological Survey Water- Resources Investigations Report , 233P. LaFave, J., Smith, L., Patton, T., 24, 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 2, 132 p, and part B, 11 plates. Smith, L., LaFave, J., and Carstarphen, C., Ground-water resources of the Lolo-Bitterroot Area: Mineral, Missoula, and Ravalli counties. Part B, 1 maps (open-file versions). 2

5 Hydrogeologic setting: Bitterroot Valley Represents Represents valleys valleys filled filled with with debris debris from from valley valley margins. margins. May May have have channel channel deposits deposits from from through through flowing streams more or less central in the flowing streams more or less central in the basin. basin. (Missoula, (Missoula, Deer Deer Lodge, Lodge, Drummond, Drummond, others) others) W E k oc dr Be Bitter ro ot Rive r Hamilton Shallow sand & gravel dr Be k oc ~2,5 ft 3

6 Kalispell Hydrogeologic setting: Kalispell Valley W E Flathead River The Kalispell valley is different because a thick alluvial sequence was deposited during the Pleistocene. The deep alluvium is the primary aquifer throughout the valley.? Tertiary? Deep Aquifer Deep alluvium ~3, ft 4

7 Hydrogeologic setting - canyons Tarkio In most canyon settings valley fill is 3-5 ft thick. Wells are developed in the near-stream alluvium or fractured bedrock along the valley margins. In the Clark Fork valley below Missoula outwash floods from Glacial Lake Missoula deepened the valley and deposited substantial thicknesses of alluvium. Glacial lake deposits NW Clark Fork Sand and gravel SE Bedrock ~4 ft 1 Mi 5

8 Intermontane basin aquifers Tertiary River Flood plain and low terraces Tributary Benches Canal Deep basin fill aquifers Shallow basin fill aquifers Canal Deep Tertiary deposits Fractured rock aquifers Ground-water flow in the intermontane basin aquifers is generally from the edges and upper ends to the center and then down valley. Important recharge sources are provided by tributaries and by irrigation canals. Water also enters the basin fill from the surrounding mountains as recharge. Confining zones may cause aquifers to be separated into near-surface and deep zones that locally may exhibit separation. However, the valley acts on a whole as a single hydrogeologic unit. 6

9 Clark Fork Basin: precipitation and discharge Precipitation/Discharge: Af X Precipitation: 22.6 m Af: Discharge: m Af Evaporation, ET, and consumptive use: 8.32 m Af Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec average monthly precipitation (Af) average discharge near Plains MT (Af) Precipitation volume based on monthly precipitation for the Western Climate Division. Precipitation data from the Western Regional Climate Center at Discharge volume from monthly average flow data measured at USGS gage12389, Clark Fork near Plains MT. The difference between water into the basin as precipitation water leaving the basin as discharge is made up by evaporation, evapotranspiration, and consumptive use. The volumes shown are to provide an order of magnitude for the amounts of water involved. Other measures may provide more refined numbers, particularly for precipitation. 7

10 Clark Fork Basin water wells Kalispell Kalispell N Thompson Falls Thompson Falls 5 mi Missoula Missoula Total wells in GWIC: 6,8 Hamilton Butte Wells since 1995: 2,679 Hamilton Butte Ground-water development is significant within the basin. Logs for more than 6, water wells are recorded in the Ground-Water Information Center (GWIC) at the Montana Bureau of Mines and Geology. Is the development intercepting water that would become surface flow, and if so, are downstream (senior) water rights being impacted? Population in the basin is increasing and many of those moving into the area drill wells for domestic and other purposes. 8

11 Ground-water development N 5 mi Wells: 6,8 Thompson Falls Kalispell Missoula Hamilton Butte Clark Fork basin above Milltown closed to new ground-water development without a SW/GW report and an augmentation plan. Well density maps provide a way to evaluate growth. The next several slides detail well-drilling densities by sub basin and the numbers of wells drilled since 199. In the notes pages are ancillary graphs showing the numbers of state wide monitoring wells, well uses, depth histograms, and construction rates. 9

12 Clark fork below Flathead River 2,529 wells: 87% Domestic 2 Mi Percent of wells Noxon 1 5 Cumulative wells Year T21N29W23: 89 wells 1 well/4 ac. 1 well/2 ac. 1 well/1 ac. 1 well/5 ac. 1 well/2.5 ac. 1 well/<2.5 ac. Plains Sections sections with wells in 2,124 mi 2 (19%) > <2.5 Acres for each well Wells 1 5 Construction rates Year 13% 87% Well use Domestic Stock Irrigation Public Supply Other Depth (ft) Total Wells 75 <= Well depths State wide Monitoring Min. Med. Max Meas Years Total wells in basin: 6 One monitoring well / 422 wells 1

13 Flathead River above Paradise 2,897 wells: 86% domestic Kalispell Polson 2 Mi Percent of wells Sections 1 T28N21W8: 132 wells 1 well/4 ac. 1 well/2 ac. 5 1, Cumulative wells Year 1 well/1 ac. 1,99 sections with wells in 8,464 mi 2 (23%) well/5 ac. 1 well/2.5 ac. 1 well/<2.5 ac > <2.5 Acres for each well Wells 6 3 Construction rates Year 14% 86% Well use Domestic Stock Irrigation Public Supply Other Depth (ft) Well depths Total Wells 9, <= State wide Monitoring Min. Med. Max Meas ,664 Years Total wells in basin: 91 One monitoring well / 23 wells 11

14 M: ft interval M: J F M A M J J A S O N D 292 M: Jan-63 Jan-71 Jan-79 Jan-87 Jan-95 Jan-3 Long-term hydrographs and development M: TD = 278 M:72938 TD =

15 Bedrock aquifer development: Kalispell Valley ,874 wells 14% 86% 13

16 Bedrock aquifer development: Kalispell Valley ,794 wells 26% 74% 14

17 Middle Clark Fork St. Regis 6,663 wells: 82% domestic Percent of wells 1 5 Cumulative wells Year T13N2W14: 267 wells 1 well/4 ac. 1 well/2 ac. 1 well/1 ac. 1 well/5 ac. 1 well/2.5 ac. 1 well/<2.5 ac. Missoula 2 Mi Sections sections with wells in 1,994 mi 2 (21%) > <2.5 Acres for each well 2 1 Wells Construction rates Year 16% 82% Well use Domestic Stock Irrigation Public Supply Other Depth (ft) Well depths Total Wells 3, <= State wide Monitoring Meas. Years Min Total wells in basin: 24 6 Med. 4 One monitoring well / 281 wells Max 7,

18 Ja n -9 6 Ja n -9 7 Ja n -9 8 Ja n -9 9 Ja n - Ja n - 1 Ja n - 2 Ja n -3 Missoula Valley Discharge (cfs) USGS station Clark Fork River Line of Section feet above mean sea level Jan- 96 Jan- 97 Jan- 98 Jan- 99 Jan Jan- 1 Jan- 2 Jan Bitterroot River Ground-Water flow 32 Clark Bitterroot Fork sand and gravel basal gravel 3 Tertiary (non aquifer) 16

19 Florence Hamilton Darby T8N2W3: 342 T6N2W31: 352 Percent of wells Sections Mi Bitterroot Year 1 well/4 ac. 1 well/2 ac. 1 well/1 ac. 46 Cumulative wells 815 sections with wells in 2,86 mi 2 (28%) well/5 ac. 1 well/2.5 ac. 1 well/<2.5 ac > <2.5 Acres for each well 18,894 wells: 87% domestic 5 Wells Construction rates Year 13% 87% Well use Domestic Stock Irrigation Public Supply Other Depth (ft) <= Well depths Total Wells 8, State wide Monitoring Meas. Years Min. Med. Max , Total wells in basin: 43 One monitoring well / 439 wells 17

20 Irrigation influence 2 Mi 18

21 Monthly averages: Each division = 2 ft Hamilton Florence Jan Mar May Jul Sep Nov N 2W 12 CDCD Total Depth (ft): N 2W 19 CCCC Total Depth (ft): 4 Surface and ground-water interaction Wells that are in aquifers heavily dependent on the distribution of surface water for irrigation have typical hydrographs similar to the Hamilton well. Water levels begin to rise quickly during a 1-2 month period after the irrigation season begins. Continual application of water throughout the irrigation season supports the water table at a high level. After irrigation water is turned off in the late summer or fall, water levels begin to fall. Wells that are in aquifers related to direct recharge by rivers or streams have hydrographs that more or less follow the discharge as recorded in the stream. Water levels will peak near the time that stream flow peaks and begin to fall back to a base level. 19

22 Bitterroot arsenic non-detect < 5. ug/l ug/l > 1. ug/l Yc Middle Belt Carbonate Tm Mylonite Zone Willow Creek Tgw Taf Yc Willow Creek and related intrusive rocks (granodiorite w/ diabase dikes. 2

23 6,1 wells: 82% domestic Upper Clark Fork Cumulative wells 1 Percent of wells Clinton Deer Lodge 5 T5N11W3: Year 6 Sections sections with wells in 2,32 mi2 (33%) > <2.5 Acres for each well Wells 25 Butte 11 well/5 well/5 ac. ac. 11 well/2.5 ac. well/2.5 ac. 11 well/<2.5 well/<2.5 ac. ac. 11 well/4 well/4 ac. ac. 11 well/2 ac. well/2 ac. 11 well/1 well/1 ac. ac. Construction rates 1975 Well use 18% Domestic Stock Irrigation Public Supply Other 82% 82% Year Well depths Depth (ft) Total Wells State wide Monitoring 2,5 Min. <= 5 Med. Max 1-2 Meas , Years Total wells in basin: 24 One monitoring well / 25 wells 21

24 Kalispell Clark Fork Basin: Nitrate 2 1 mg/l 12% 34% < 2 mg/l.3% > 1 mg/l 54% non detect. 71 samples W/O Butte Missoula 11% 48% 3% 11% 47 samples near Butte MBMG Ground-Water Assessment Program 22

25 Blackfoot Basin 2,769 wells: 88% domestic Seeley Lake T14N9W24: 149 Percent of wells 1 5 Cumulative wells Year Potomac Lincoln Sections sections with wells in 2,316 mi2 (2%) 1 well/4 ac. 1 well/2 ac. 1 well/1 ac. 1 well/5 ac. 1 well/2.5 ac. 1 well/<2.5 ac > <2.5 Acres for each well 75 Wells Construction rates Year 12% 88% Well use Domestic Stock Irrigation Public Supply Other Depth (ft) Total Wells 1, <= Well depths State wide Monitoring Meas. Years Min. Med. Max , Total wells in basin: 1 One monitoring well / 279 wells 23

26 Rock and Flint Creek Basins 1,428 wells: 89% domestic Drummond Percent of wells 1 5 Cumulative wells Year T5N14W24: 16 Georgetown Lake Sections sections with wells in 1,281 mi2 (19%) > <2.5 Acres for each well 1 well/4 ac. 1 well/2 ac. 1 well/1 ac. 1 well/5 ac. 1 well/2.5 ac. 1 well/<2.5 ac. 5 Wells Construction rates Year 11% 89% Well use Domestic Stock Irrigation Public Supply Other Depth (ft) Well depths Total Wells 5 <= State wide Monitoring Meas. Years Min Med Total wells in basin: 9 One monitoring well / 159 wells Max 8,

27 Clark Fork: well densities 15 <= 8 Wells Wells Rock/Flint Rock/Flint Lower Lower C.F. C.F. Blackfoot Blackfoot Upper C.F Middle Middle C.F. C.F. Flathead Flathead Bitterroot Bitterroot 1 5 Sections 25

28 Clark Fork: drilling rates 4, 3, Year Year Rock/Flint Rock/Flint Lower Lower C.F. C.F. Blackfoot Blackfoot Upper C.F. Middle Middle C.F. C.F. Bitterroot Bitterroot Flathead Flathead 2, 1, Wells 26

29 2% 6% 1% 11% Clark Fork: development 71% %, % 1 well per 8 ac. 4 ac. 2 ac. 1 ac 5 ac. 2.5 ac <2.5 ac. 23 percent (5,21 sections in 21,349 mi 2 ) of the basin s sections contain wells. Wells x 1, 2 1 Construction rates During the last 15 years about 1,8 wells have been constructed each year Year 27

30 Summary: a water balance? Million A/f Sources average based on Precipitation 22.6 Western Climate Division data. Discharge average annual discharge near Plains. Irrigation.28 MT DNRC water rights listings for irrigation use September 26. Municipal.21 MT DNRC water rights listings for municipal use September 26. Domestic.8 ~ 52, 1.5 af consumptive use each. Evap./ET 7.75 By difference. 28

31 Missoula Wells Cumulative number of wells above Missoula 87% are domestic wells Darby

32 Missoula Wells Cumulative number of wells above Missoula 87% are domestic wells Darby cfs Bitterroot River: mean monthly 18 flow at Missoula

33 Missoula Wells Cumulative number of wells above Missoula 87% are domestic wells Darby cfs Bitterroot River: mean monthly flow and annual precipitation at Missoula In/yr 31

34 Missoula well Wells Cumulative number of wells above Missoula 87% are domestic wells Darby cfs Mean monthly flow at Missoula and Ground-water level at Florence 15 2 Well Ft below ground 32

35 GWIC Slide Most of the ground-water information presented today can be obtained from the Ground-Water Information Center at the Montana Bureau of Mines and Geology. Well logs, water-quality data, water-level data and Ground-Water Characterization Program maps products can be obtained from the website at http\:mbmggwic.mtech.edu. 33

36 Montana Ground- Water Assessment September 27, 26 Well 11131: 1S 16E 28 BADC- Stillwater County (unused) 34