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Montana water data · County

Yellowstone County: well depth, groundwater and water rights

What the public record says about water in Yellowstone 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 29,926 public records from MBMG GWIC, Montana DNRC, Montana DEQ, EPA SEMS, EPA UST Finder

Wells on record

16,088

14,904 with recorded depth

Median well depth

35 ft

half of wells 25–78 ft

Median static water level

15 ft

13,619 measurements

Median tested yield

24 gpm

12,455 pump tests

Well depth

How deep are wells in Yellowstone County?

Of 14,904 wells with a recorded total depth, the median is 35 feet. Half were drilled between 25 and 78 feet; one in ten went deeper than 190 feet and one in ten found water shallower than 20 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
63%
50–100 ft
16%
100–200 ft
11%
200–300 ft
5%
300–500 ft
3%
500 ft and deeper
1%

Static water level

15 ft

median depth to water at rest · half between 10 and 27 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

24 gpm

median tested yield · half between 12 and 35 gpm

9% of tested wells produced under 5 gallons per minute and 63% 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 Yellowstone County

2,348 wells have been completed here since 2016, 154 of them in the last twelve months. The newest log on file was completed September 17, 2026. Records run back to 1881.

What the wells are for

  • Domestic9,224
  • Irrigation2,907
  • Stockwater2,717
  • Monitoring2,422
  • Unused225

How they were drilled

  • Rotary6,753
  • Forward Rotary2,247
  • Cable1,125
  • Hollowstem Auger793

Drillers filing well logs in Yellowstone County

  • American Drilling & Supply640 since 2016 · 2026
  • Bertram Drilling Inc336 since 2016 · 2026
  • Aaqua Drilling Inc310 since 2016 · 2026
  • Haz Tech Drilling Inc238 since 2016 · 2026
  • A-1 Drilling173 since 2016 · 2026
  • Mayes Drilling Inc172 since 2016 · 2026
  • Cascade Drilling Lp136 since 2016 · 2024
  • Gary's Drilling Inc.71 since 2016 · 2025

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 Yellowstone County

Montana DNRC lists 12,829 water rights in the county: 10,680 groundwater and 2,149 surface water, 11,893 of them active. The median priority date is 1982, and the oldest claim dates to 1868.

Types of right

  • Ground Water Certificate8,750
  • Statement Of Claim3,149
  • Provisional Permit348
  • Exempt Notice188
  • Converted Terminates172

Purposes

  • Domestic4,190
  • Stock2,982
  • Lawn And Garden1,541
  • Domestic; Lawn And Garden1,134
  • Irrigation657

DNRC basins

  • 43Q11,089
  • 43E723
  • 43QJ561
  • 43D220
  • 42KJ153

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 Yellowstone 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.

  • Terrace Deposits (holocene)3,242 wells · 30% · median 29 ft
  • Alluvium (holocene)2,144 wells · 20% · median 30 ft
  • Terrace Deposits (pleistocene)1,307 wells · 12% · median 31 ft
  • Alluvium (pleistocene)764 wells · 7% · median 26 ft
  • Judith River Formation (of Montana Group)746 wells · 7% · median 130 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 Yellowstone County

Petroleum releases

463

118 open · 345 resolved

Superfund program sites

5

2 on or proposed for the NPL

Registered tank facilities

541

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.