Montana WaterReport
Check a property

Montana water data · County

Petroleum County: well depth, groundwater and water rights

What the public record says about water in Petroleum 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 3,466 public records from MBMG GWIC, Montana DNRC, Montana DEQ, EPA UST Finder

Wells on record

785

670 with recorded depth

Median well depth

160 ft

half of wells 36–1,043 ft

Median static water level

33 ft

319 measurements

Median tested yield

10 gpm

486 pump tests

Well depth

How deep are wells in Petroleum County?

Of 670 wells with a recorded total depth, the median is 160 feet. Half were drilled between 36 and 1,043 feet; one in ten went deeper than 1,526 feet and one in ten found water shallower than 18 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
28%
50–100 ft
8%
100–200 ft
20%
200–300 ft
8%
300–500 ft
3%
500 ft and deeper
33%

Static water level

33 ft

median depth to water at rest · half between 13 and 90 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

10 gpm

median tested yield · half between 5 and 20 gpm

22% of tested wells produced under 5 gallons per minute and 28% 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 Petroleum County

37 wells have been completed here since 2016, 1 of them in the last twelve months. The newest log on file was completed November 11, 2025. Records run back to 1900.

What the wells are for

  • Stockwater410
  • Domestic130
  • Monitoring105
  • Industrial48
  • Waterflood48

How they were drilled

  • Rotary211
  • Forward Rotary57
  • Unknown53
  • Cable Tools27

Drillers filing well logs in Petroleum County

  • Central Drilling Inc11 since 2016 · 2025
  • Hole World Consulting Llc5 since 2016 · 2023
  • Gordon Drilling Inc4 since 2016 · 2017
  • Haz Tech Drilling Inc4 since 2016 · 2020
  • Vidic Drilling Inc3 since 2016 · 2021
  • Olympus Technical Services3 since 2016 · 2019
  • Singley Drilling2 since 2016 · 2021
  • Montana Salinity Control Association71 all-time · 2009

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 Petroleum County

Montana DNRC lists 2,663 water rights in the county: 510 groundwater and 2,153 surface water, 2,390 of them active. The median priority date is 1953, and the oldest claim dates to 1860.

Types of right

  • Statement Of Claim2,110
  • Ground Water Certificate246
  • Provisional Permit159
  • Stockwater Permit97
  • Compact21

Purposes

  • Stock1,762
  • Irrigation369
  • Wildlife284
  • Domestic49
  • Stock; Wildlife/waterfowl29

DNRC basins

  • 40B1,495
  • 40C1,117
  • 40EJ50
  • 40A1

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 Petroleum 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.

  • Eagle Sandstone109 wells · 37% · median 153 ft
  • Third Cat Creek Sandstone (basal Kootenai Fm)53 wells · 18% · median 1,335 ft
  • First Cat Creek Sandstone (base Of Colorado Gp)24 wells · 8% · median 1,319 ft
  • Alluvium (quaternary)22 wells · 8% · median 30 ft
  • Kootenai Formation17 wells · 6% · median 1,092 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 Petroleum County

Petroleum releases

9

3 open · 6 resolved

Superfund program sites

0

none on the National Priorities List

Registered tank facilities

9

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 2019. A property report screens the sites within a quarter, half and one mile of a specific parcel and links the agency records.