Yellowstone County Water Quality: 87 Violations (MT)
9 water systems · 6 ZIP codes · Home Safety Score 78/100 (B) · 5 of 23 tracked ZIP records scored · Updated
Data: EPA Safe Drinking Water Information System (SDWIS), EPA ECHO Last verified:
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Find the Right Filter →Water Quality Overview
Yellowstone County has 9 community water systems across 6 directly mapped ZIP records. The systems report serving approximately 140,102 people. The available records contain 87 EPA violations, including 5 health-based violations.
Health-based violations account for 6% of all violations in Yellowstone County. These violations indicate contaminant levels that may pose direct risks to human health.
Violation Breakdown
| Violation Type | Count | Percentage |
|---|---|---|
| Health-based | 5 | 5.7% |
| Monitoring/Reporting | 82 | 94.3% |
| Total | 87 | 100% |
Health-based violations indicate contaminant levels exceeding EPA Maximum Contaminant Levels (MCLs). Monitoring violations indicate failures to test or report.
Cities with Most Violations
| Rank | City | Violations | Health-Based | ZIP Codes | Population |
|---|---|---|---|---|---|
| 1 | Billings | 84 | 4 | 4 | 145,092 |
| 2 | Laurel | 3 | 1 | 1 | 12,488 |
Most Common Contaminants
| Contaminant | Category | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|
| Stage 1 DBP Rule | Treatment Technique | 13 | 4 | No |
| Surface Water Treatment Rule | Treatment Technique | 11 | 5 | No |
| Arsenic | Inorganic | 10 | 2 | Yes |
| Total Trihalomethanes (TTHM) | Disinfection Byproducts | 5 | 3 | No |
| Haloacetic Acids (HAA5) | Disinfection Byproducts | 5 | 3 | No |
| PFOA | PFAS | 2 | 2 | No |
| PFNA | PFAS | 2 | 2 | No |
| Monochloroacetic Acid | Disinfection Byproducts | 2 | 2 | No |
| Dichloroacetic Acid | Disinfection Byproducts | 2 | 2 | No |
| Bromodichloromethane | Disinfection Byproducts | 2 | 2 | No |
Water Data and the Home Safety Score
This page reports EPA water-system facts without converting the broader Home Safety Score into a drinking-water grade. The county Home Safety grade (B) is a separate multi-source index that also requires PFAS screening, radon, and annual air-quality evidence. Check each ZIP report for the versioned score and its component coverage.
Water Systems in Yellowstone County
Yellowstone County is served by 9 community water systems, averaging 0.4 systems per ZIP code. Each system is independently regulated and tested by the EPA. Larger systems serving more people typically have more extensive monitoring requirements.
Water systems in Yellowstone County source water from a mix of surface water (rivers, reservoirs) and groundwater (wells, aquifers). Source type affects which contaminants are most likely to be detected.
How to Check Your Water in Yellowstone County
Enter your ZIP code on ZipCheckup for detailed water-system data including contaminant levels and violation history; the Home Safety Score is shown separately with its model version
Request your CCR — every water utility must provide an annual Consumer Confidence Report
Get a home test — certified kits ($20-$50) or professional lab tests ($150-$400) can detect contaminants not covered by routine testing
Consider filtration — NSF-certified filters can address specific contaminants found in your area
Check for lead — homes built before 1986 should test for lead regardless of utility compliance
EPA Enforcement
The EPA and state regulators have taken 58 enforcement actions against water systems in Yellowstone County. Enforcement actions range from compliance assistance and administrative orders to formal penalties. Systems under enforcement are required to remediate violations and may face ongoing monitoring requirements.
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Enforcement: EPA ECHO
Source publication schedules vary. See the page source and verification fields for available timing evidence.
Water Quality by ZIP Code in Yellowstone County
Water quality varies across Yellowstone County's 6 ZIP codes. Check your specific ZIP for detailed contaminant data.
Water facts and the Home Safety Score
The score shown here is the broader Home Safety Score, not a water-quality grade. Model 4.0.0 combines EPA SDWIS identity plus accepted ECHO SDWA lifecycle-based water compliance, PFAS screening, radon zones, and annual air-quality evidence. Yellowstone County has a score of 78/100 (Grade B) across 5 scored of 23 tracked ZIP records.
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Find the Right Filter →Frequently Asked Questions
Is the tap water safe in Yellowstone County, Montana?
Yellowstone County has 9 community water systems with 87 recorded EPA violations, including 5 health-based. Water quality varies by ZIP code - check your specific location for detailed results.
How many water violations does Yellowstone County have?
Yellowstone County has 87 total EPA violations across 6 directly mapped ZIP records. 5 are health-based.
Which city in Yellowstone County has the most water violations?
Billings has the most violations in Yellowstone County with 84 recorded EPA violations across 4 ZIP codes.
What contaminants are found in Yellowstone County water?
Yellowstone County water systems are monitored for over 90 EPA-regulated contaminants including lead, copper, nitrates, disinfection byproducts, and bacteria. Check your ZIP code for contaminant-specific data.
How can I test my water in Yellowstone County?
Contact your local water utility for free or low-cost testing. You can also use a certified home test kit ($20-$50) or hire a certified lab ($150-$400).