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Montana water data · County

Custer County: well depth, groundwater and water rights

What the public record says about water in Custer 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 11,873 public records from MBMG GWIC, Montana DNRC, Montana DEQ, EPA SEMS, EPA UST Finder

Wells on record

3,393

3,104 with recorded depth

Median well depth

180 ft

half of wells 80–331 ft

Median static water level

60 ft

2,518 measurements

Median tested yield

15 gpm

2,768 pump tests

Well depth

How deep are wells in Custer County?

Of 3,104 wells with a recorded total depth, the median is 180 feet. Half were drilled between 80 and 331 feet; one in ten went deeper than 560 feet and one in ten found water shallower than 25 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
19%
50–100 ft
9%
100–200 ft
25%
200–300 ft
17%
300–500 ft
17%
500 ft and deeper
13%

Static water level

60 ft

median depth to water at rest · half between 20 and 140 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

15 gpm

median tested yield · half between 8 and 20 gpm

10% of tested wells produced under 5 gallons per minute and 37% 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 Custer County

455 wells have been completed here since 2016, 22 of them in the last twelve months. The newest log on file was completed August 20, 2026. Records run back to 1880.

What the wells are for

  • Stockwater2,000
  • Domestic1,144
  • Monitoring365
  • Irrigation124
  • Public Water Supply40

How they were drilled

  • Rotary1,143
  • Forward Rotary391
  • Hollowstem Auger181
  • Unknown55

Drillers filing well logs in Custer County

  • Askin Drilling269 since 2016 · 2026
  • Higgins Drilling Company88 since 2016 · 2025
  • Haz Tech Drilling Inc40 since 2016 · 2025
  • Olympus Technical Services27 since 2016 · 2026
  • West Central Environmental Consultants24 since 2016 · 2024
  • Sharp Drilling Inc9 since 2016 · 2023
  • Gordon Drilling Inc2 since 2016 · 2018
  • American Drilling & Supply2 since 2016 · 2019

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 Custer County

Montana DNRC lists 8,334 water rights in the county: 3,854 groundwater and 4,480 surface water, 7,880 of them active. The median priority date is 1956, and the oldest claim dates to 1864.

Types of right

  • Statement Of Claim3,769
  • Powder River Declaration2,087
  • Ground Water Certificate1,697
  • Stockwater Permit341
  • Provisional Permit211

Purposes

  • Stock5,926
  • Irrigation813
  • Domestic532
  • Domestic; Stock243
  • Wildlife210

DNRC basins

  • 42J2,769
  • 42C2,393
  • 42K1,954
  • 42KJ621
  • 42L519

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 Custer 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.

  • Tullock Member (of Ft Union Fm.)964 wells · 45% · median 167 ft
  • Fox Hills-hell Creek Aquifer682 wells · 32% · median 399 ft
  • Tongue River Member (of Ft Union Fm.)155 wells · 7% · median 140 ft
  • Lance-hell Creek Undifferentiated137 wells · 6% · median 591 ft
  • Sand And Gravel (holocene)104 wells · 5% · median 22 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 Custer County

Petroleum releases

67

21 open · 46 resolved

Superfund program sites

1

none on the National Priorities List

Registered tank facilities

78

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 2025. A property report screens the sites within a quarter, half and one mile of a specific parcel and links the agency records.