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Montana water data · County

Lewis and Clark County: well depth, groundwater and water rights

What the public record says about water in Lewis and Clark County: how deep wells go, where the water table sits, what wells produce, which water rights are on file, and which documented environmental sites are nearby. Area statistics orient you; a property report analyzes the records around one specific parcel.

Updated September 2026 · Based on 38,616 public records from MBMG GWIC, Montana DNRC, Montana DEQ, EPA SEMS, EPA UST Finder

Wells on record

17,655

16,813 with recorded depth

Median well depth

105 ft

half of wells 60–195 ft

Median static water level

39 ft

16,041 measurements

Median tested yield

20 gpm

15,608 pump tests

Well depth

How deep are wells in Lewis and Clark County?

Of 16,813 wells with a recorded total depth, the median is 105 feet. Half were drilled between 60 and 195 feet; one in ten went deeper than 340 feet and one in ten found water shallower than 39 feet. Depth is set by local geology and position on the landscape, both of which change over short distances, so the spread matters as much as the median.

under 50 ft
16%
50–100 ft
29%
100–200 ft
30%
200–300 ft
11%
300–500 ft
9%
500 ft and deeper
4%

Static water level

39 ft

median depth to water at rest · half between 17 and 73 ft

The static level is how far below ground the water stands before pumping, measured by the driller at completion. It affects pump setting and operating cost, and it moves with season and with neighbouring use.

Well yield

20 gpm

median tested yield · half between 15 and 30 gpm

4% of tested wells produced under 5 gallons per minute and 65% produced 20 or more. These are short completion tests, not sustained-capacity tests; a household typically needs 3 to 5 gpm with storage.

Drilling activity

Recent well drilling in Lewis and Clark County

2,818 wells have been completed here since 2016, 188 of them in the last twelve months. The newest log on file was completed September 15, 2026. Records run back to 1860.

What the wells are for

  • Domestic14,002
  • Monitoring1,327
  • Stockwater968
  • Irrigation826
  • Public Water Supply356

How they were drilled

  • Rotary8,807
  • Cable2,224
  • Air Rotary1,944
  • Churn423

Drillers filing well logs in Lewis and Clark County

  • H & L Drilling Inc881 since 2016 · 2026
  • A-10 Drilling702 since 2016 · 2026
  • Western Water Wells447 since 2016 · 2026
  • Aaaa Water Well Drilling Inc177 since 2016 · 2026
  • Mt Poverty Water Well Drilling112 since 2016 · 2022
  • Lindsay Drilling Co Inc106 since 2016 · 2026
  • Okeefe Drilling Co77 since 2016 · 2026
  • 406 Water Wells, Llc55 since 2016 · 2026

Ranked by well logs filed with GWIC, public record only. Not an endorsement, a referral or a paid listing; we have no business relationship with these companies. Verify licensing with the Montana Board of Water Well Contractors before hiring.

Water rights

Water rights on file in Lewis and Clark County

Montana DNRC lists 20,416 water rights in the county: 15,377 groundwater and 5,039 surface water, 18,273 of them active. The median priority date is 1982, and the oldest claim dates to 1858.

Types of right

  • Ground Water Certificate11,642
  • Statement Of Claim7,019
  • Provisional Permit686
  • Exempt Notice557
  • Converted Terminates279

Purposes

  • Domestic6,576
  • Stock4,071
  • Domestic; Lawn And Garden3,296
  • Irrigation1,932
  • Domestic; Lawn And Garden; Stock488

DNRC basins

  • 41I13,276
  • 41K2,112
  • 41QJ2,040
  • 76F1,761
  • 41U1,101

Area totals describe the neighbourhood, not any one parcel. Montana publishes no authoritative link between a parcel and a water right; whether a right attaches to a specific property is a property-level question that our reports answer with the DNRC abstract linked.

Aquifers and geology

What wells in Lewis and Clark County draw from

Drillers record the aquifer a well is completed in. The units below account for the wells here that carry an aquifer assignment; the median depth beside each is for wells completed in that unit.

  • Alluvium (quaternary)1,982 wells · 54% · median 50 ft
  • Sediments (tertiary)499 wells · 14% · median 105 ft
  • Spokane Shale221 wells · 6% · median 137 ft
  • Alluvium (holocene)212 wells · 6% · median 70 ft
  • Helena Dolomite196 wells · 5% · median 155 ft

Aquifer assignments are the driller's, recorded at completion, and many older logs carry none. Absence of an assignment is not evidence about the geology.

Environmental groundwater screening

Documented environmental sites in Lewis and Clark County

Petroleum releases

248

47 open · 201 resolved

Superfund program sites

13

2 on or proposed for the NPL

Registered tank facilities

284

underground storage tanks, current and historical

A documented release or site in the area is not evidence that any particular well is affected. Whether a release reaches a well depends on groundwater flow direction, geology, well depth and construction, the extent of the plume and the cleanup performed. The most recent release reported here dates to 2026. A property report screens the sites within a quarter, half and one mile of a specific parcel and links the agency records.