Big Horn County, Montana — public water systems
At a glance
23 active public water systems are filed under Big Horn County, Montana in EPA's SDWIS records, together reporting 10,335 people served. The largest is City of Hardin, which reports serving 3,500 people. 5 are community water systems serving people where they live; the other 18 are non-community systems, such as schools, workplaces, campgrounds and gas stations with their own supply.
Dataset updated . Source: EPA SDWIS/ECHO, refreshed quarterly.
Active systems
23
Population served
10.3K
Community systems
5
Groundwater share
65.2%
How does Big Horn County compare with other Montana counties?
Big Horn County has the 21st-most active public water systems among the 76 counties listed for active Montana systems in EPA records; among the 55 with 3 or more systems, the median has 16. Its systems report 10,335 people served in total, the 19th-largest county figure in the state and 0.9% of the statewide total. The average system here reports serving 449 people, roughly in line with the Montana average of 489. Population figures are what each system reports; people served by more than one system, such as a wholesaler and the town that buys from it, are counted by each.
Where does Big Horn County's drinking water come from?
By primary water source, Big Horn County's active systems draw on groundwater (15, 65%), purchased surface water (6, 26%) and surface water (2, 8.7%). Overall, 65% rely mainly on groundwater (including purchased groundwater) and 35% on surface water, compared with 89% and 11% across Montana. Groundwater means the system draws its water from wells or springs fed by underground aquifers. The county's largest system, City of Hardin, draws primarily on surface water.
What kinds of water systems operate in Big Horn County?
Big Horn County's active systems break down as 5 community systems (22%), 6 non-transient non-community systems (26%) and 12 transient non-community systems (52%). A community water system serves at least 15 connections used by year-round residents, or regularly serves at least 25 year-round residents. Homes, apartments and mobile-home parks are served by these. A non-transient non-community water system regularly serves at least 25 of the same people for more than six months a year, but not where they live. Schools, factories, office buildings and hospitals with their own supply are typical examples. A transient non-community water system serves places where people do not stay long, such as gas stations and campgrounds, and regularly serves at least 25 people a day for at least 60 days a year. EPA lists their owner types as private (48%), state government (22%), local government (17%) and federal government (13%).
Water systems in Big Horn County
🔒 Create a free account to export CSV| # | Water system | County | Population served | Type | Source |
|---|---|---|---|---|---|
| 1 | Hardin City of | Big Horn | 3,500 | Community | Surface water |
| 2 | Little Bighorn Battlefield Nm | Big Horn | 2,020 | Non-transient non-community | Groundwater |
| 3 | Hardin Eastbound Rest Area | Big Horn | 877 | Transient non-community | Groundwater |
| 4 | Hardin Westbound Rest Area | Big Horn | 715 | Transient non-community | Groundwater |
| 5 | Lodge Grass Town of | Big Horn | 480 | Community | Groundwater |
| 6 | Fort Smith Water and Sewer District | Big Horn | 450 | Community | Groundwater |
| 7 | Tongue River Campers Point | Big Horn | 305 | Transient non-community | Groundwater |
| 8 | Tongue River Pee Wee Point | Big Horn | 300 | Transient non-community | Groundwater |
| 9 | Chief Plenty Coups Museum | Big Horn | 262 | Transient non-community | Groundwater |
| 10 | Big Horn Co Historical Museum | Big Horn | 206 | Transient non-community | Purchased surface water |
| 11 | Spring Creek Mine | Big Horn | 200 | Non-transient non-community | Purchased surface water |
| 12 | Spring Creek Coal Domestic | Big Horn | 200 | Non-transient non-community | Groundwater |
| 13 | St Charles School | Big Horn | 152 | Non-transient non-community | Groundwater |
| 14 | Yellowtail Dam Gc System | Big Horn | 125 | Community | Groundwater |
| 15 | 7th Ranch Rv Camp | Big Horn | 102 | Transient non-community | Groundwater |
| 16 | Hardin Koa Cistern | Big Horn | 100 | Transient non-community | Purchased surface water |
| 17 | Cottonwood Camp Fort Smith | Big Horn | 85 | Transient non-community | Groundwater |
| 18 | Absaloka Mine | Big Horn | 80 | Non-transient non-community | Purchased surface water |
| 19 | Wegner Water Service Hauler | Big Horn | 50 | Community | Purchased surface water |
| 20 | Yellowtail Dam Powerplant and Visitor Ce | Big Horn | 48 | Transient non-community | Surface water |
| 21 | East Decker Coal Mine | Big Horn | 28 | Non-transient non-community | Groundwater |
| 22 | Reese and Ray Iga Hardin | Big Horn | 25 | Transient non-community | Purchased surface water |
| 23 | Kirby Saloon | Big Horn | 25 | Transient non-community | Groundwater |
Big Horn County water systems: frequently asked questions
How many public water systems are in Big Horn County, Montana?
EPA's SDWIS records file 23 active public water systems under Big Horn County, Montana: 5 community systems (22%), 6 non-transient non-community systems (26%) and 12 transient non-community systems (52%).
Who supplies drinking water in Big Horn County, MT?
The largest community water systems filed under Big Horn County are City of Hardin (3,500 people served), Town of Lodge Grass (480 people served) and Fort Smith Water and Sewer District (450 people served). Which system serves a particular address depends on its service area, which EPA's SDWIS records do not include; a water bill or the local utility can confirm it.
Does Big Horn County's drinking water come from groundwater or surface water?
Of the 23 active public water systems in Big Horn County, 65% draw mainly on groundwater and 35% on surface water, counting purchased supplies. The largest system, City of Hardin, uses surface water.
Where can I find a water quality report for Big Horn County?
Each community water system must deliver an annual water quality report, called a Consumer Confidence Report, to its customers by July 1, covering the previous calendar year. 5 community systems are filed under Big Horn County, so the report to look for is the one from the system that supplies your address.
How can I check violations for a water system in Big Horn County?
Open the system's profile from the list on this page. Each profile shows the most recent Safe Drinking Water Act violations in EPA's records, with plain-English labels and whether each one is resolved. For current compliance status, EPA ECHO is the primary source.
More Montana water systems
- All Montana public water systems· 2,378 active
- Dawson County· 32 systems
- Stillwater County· 30 systems
- Glacier County· 27 systems
- Silver Bow County· 24 systems
- Fergus County· 21 systems
- Granite County· 21 systems
- How to find out who supplies your drinking water
- How to find and read your annual water quality report
About this data
Source: U.S. EPA Safe Drinking Water Information System (SDWIS) and SDWA violation records, via EPA ECHO, as published October 1, 2026 — AquaCensus refreshes it quarterly. See the methodology for how records are matched, cleaned and scored.
Cite as: AquaCensus, “Public water systems in Big Horn County, Montana”, https://aquacensus.com/water-systems/montana/big-horn (data as of October 1, 2026).