Hardness
Very Hard
235 PPM · 13.7 GPG
Local water dashboard
Official source aggregationA source-transparent look at local hardness, associated public water systems, EPA compliance history, and the measurements that are—and are not—available for Yellowstone County.
At a glance
EPA quarter 2026Q2
Hardness
Very Hard
235 PPM · 13.7 GPG
Compliance screen
No active flag
0 active health-based records
Lead 90th percentile
0 mg/L
0% of action level
Utility match
1 system
Serves 100 people system-wide
Hardness meter
Estimated local hardness
USGS hardness classification scale
235 PPM
Parts per million
235
mg/L as CaCO₃ equivalent
Grains per gallon
13.7
1 GPG ≈ 17.1 PPM
What this means at home
At 235 PPM, mineral scale can build up on fixtures and heating elements, reduce soap lather, and leave visible spotting. Hardness is primarily an aesthetic and appliance concern—not itself a tap-water safety rating.
USGS sites used
8
Nearest site
55.8 mi
Observation range
Aug 23, 2016–Aug 29, 2016
Estimate confidence
Low
Median of the latest qualifying hardness observation at each nearby monitoring site. Nearest monitoring location: BL-1 Afterbay below Yellowtail Dam (Lake, Reservoir, Impoundment).USGS source documentation ↗
Regional context
These comparisons use other indexed ZIP estimates, not utility tap samples. They help show local context without replacing a household test.
Shepherd median
235 PPM
About the same1 indexed ZIP readings · Range 235–235 PPM
Montana median
122 PPM
113 PPM higher129 indexed ZIP readings · Range 0.2–799.5 PPM
EPA benchmark screen
Available numerical results from associated SDWIS community water systems, compared with the applicable action level or federal MCL. Federal measured-value coverage is incomplete.
Lead (PB90)
0 mg/L
Reported Dec 31, 2027
Copper (CU90)
Not available
No numerical 90th-percentile result
Numerical coverage
1 comparable result
Missing values remain blank; absence is not treated as a pass.
Measured in mg/L
Local 0
EPA limit 0.015
100% line = listed limit
| Contaminant or rule | System | Status | Period |
|---|---|---|---|
| E. COLI | MT0004920 | Resolved | Dec 18, 2025through Jan 8, 2026 |
| Lead and Copper Rule | MT0004920 | Resolved | Oct 1, 2024through Aug 29, 2025 |
| E. COLI | MT0004920 | Resolved | Jul 18, 2023through Jul 20, 2023 |
| Revised Total Coliform Rule | MT0004920 | Resolved | Oct 1, 2022through Oct 31, 2022 |
| Revised Total Coliform Rule | MT0004920 | Resolved | Sep 1, 2022through Sep 30, 2022 |
| Revised Total Coliform Rule | MT0004920 | Resolved | Feb 1, 2022through Feb 28, 2022 |
| Lead and Copper Rule | MT0004920 | Resolved | Dec 30, 2021through Jan 13, 2022 |
| Consumer Confidence Rule | MT0004920 | Resolved | Jul 1, 2021through Sep 3, 2021 |
No reported violation does not prove that every contaminant was tested or absent; SDWIS measured values are incomplete and lag state records.
Solutions matcher
Matched to Shepherd ZIP 59079 using 235 PPM nearby hardness and 1 reported measurement benchmarks.
Scale protection
235 PPM is 2× the high-hardness trigger used by this matcher.
Designed to reduce scale on fixtures, water heaters, glassware, and plumbing throughout the home.
Compare whole-house systemsAffiliate disclosure: we may earn a commission from qualifying purchases, at no added cost to you. Product matching is educational and does not replace certified water testing.
Frequently asked
EPA ECHO shows no active health-based violation for the associated systems in this reporting snapshot. This does not prove every contaminant is absent; federal records can lag and household plumbing can change tap conditions.
Nearby USGS observations produce an estimate of 235 PPM, or 13.7 grains per gallon, classified as very hard. This is not a household tap measurement.
At 235 PPM, a correctly sized whole-house softener can reduce scale and hard-water spotting. It does not replace contaminant filtration.