Abandoned mines in Sheridan County, Montana

1. Mine openings

   shafts, adits, air shafts, portals and vertical openings: the ways into underground workings
   30 20.5%
2. Prospect pits and trenches

   shallow exploration diggings that never became a mine
   3 2.1%
3. Mines and surface workings

   labelled mines, open pits, strip mines, placer and hydraulic workings
   3 2.1%
4. Quarries, gravel and borrow pits

   construction-material and industrial-mineral extraction
   45 30.8%
5. Dumps, tailings, spoil and gob

   what mining left above ground
   9 6.2%
6. Mills, tipples and facilities

   processing plants and hazardous structures
   5 3.4%
7. Other reclamation problems

   highwalls, subsidence, polluted or clogged water, fires, slides and gases in OSMRE's inventory
   51 34.9%

Problem types carry OSMRE's priority prefix: P1 and P2 are threats to health, safety and property, P3 is environmental. A problem area is a cluster of problems reclaimed as one project; several rows can share one location.

1. George Gill Construction Pit #1

   Surface metal/non-metal · George Gill Construction · MSHA ID 2402645
   Abandoned 2020-04-22
2. K & K Opsahl Pit Area 2 Site

   Surface metal/non-metal · Oilfield Rock & Logistics LLC · MSHA ID 2402628
   Abandoned 2013-08-16
3. MEDICINE LAKE PIT

   Surface metal/non-metal · Prairie Sand & Gravel Inc · MSHA ID 2401396
   Abandoned 2001-09-11
4. S R M PORTABLE

   Surface metal/non-metal · Sheridan Ready Mix Inc · MSHA ID 2401801
   Abandoned 1997-11-05
5. Screen Plant

   Surface metal/non-metal · CM Owen Construction · MSHA ID 2402635
   Abandoned 2015-12-14
6. Sheridan Ready Mix

   Surface metal/non-metal · Montana Aggregate Holdings Inc · MSHA ID 2400792
   Abandoned 2018-12-06
7. SRM-1

   Surface metal/non-metal · Idlewild Group Inc · MSHA ID 2402632
   Abandoned 2013-02-07

Status and date are as reported to MSHA by the operator. Each mine's own page carries its accident, citation and inspection record.

• Madison County 3,766
• Silver Bow County 2,397
• Jefferson County 1,973
• Lewis and Clark County 1,862
• Broadwater County 1,418
• Beaverhead County 1,378
• Carbon County 769
• Powell County 741
• Granite County 719
• Cascade County 708
• Deer Lodge County 688
• Fergus County 550

1. USGS, Consolidated Prospect- and Mine-Related Features from 7.5- and 15-Minute Topographic Quadrangle Maps of the United States (USMIN)
   597,612 point and area features digitized from about 106,350 historical topographic maps published 1886–2006; public domain (CC0). A feature is a map symbol, not a field-verified site, and the map does not say whether it was still worked.
2. USGS Fact Sheet 2025–3003, The Abandoned Mine Inventory of the United States
   States that as of 2025 there is no comprehensive national inventory of abandoned mine features, and that the detailed national database now being built will not be published.
3. OSMRE, Abandoned Mine Land Inventory System (e-AMLIS), public Problems layer
   One row per abandoned mine land problem in a problem area, with its type, funding program and reclamation status; mostly coal mined before the 1977 Surface Mining Control and Reclamation Act. Coordinates are the problem area's.
4. MSHA, Mines dataset (Mine Data Retrieval System)
   Every mine registered with MSHA since the 1970s; a mine reads Abandoned or Abandoned and Sealed when its operator reported that status. Refreshed weekly.
5. US Census Bureau, 2023 cartographic county boundaries (1:500,000)
   Each feature's county is assigned by its coordinates against these boundaries, not copied from the source file.
6. GAO-20-238, Abandoned Hardrock Mines (March 2020)
   Federal agencies had identified at least 140,000 abandoned hardrock mine features on federal land and estimated more than 390,000 more not yet captured in their databases.
7. Abandoned Hardrock Mine Reclamation (AHMR) Program, US Department of the Interior
   The program the USGS inventory is compiled for. Its appropriations and the 674,000 field-confirmed feature count on this page were provided by the program manager, Office of Environmental Policy and Compliance, and are cited with permission (2026-09-08).
8. IMCC-NAAMLP Hardrock AML Report
   Page 48 carries the two figures this page leans on: USGS estimates 633,181 of the 725,690 mine features it recorded from historic topographic maps, 87 percent, are hardrock; and state and federal agencies have submitted more than 724,000 AML features to the national database being built, already more than the historic maps hold. Year-by-year AHMR funding is on page 35.