Jefferson County, Montana
8 ZIP codes · Avg score 48/100 · Grade D · Updated 2026-06-03
Of 8 ZIP codes in Jefferson County, a meaningful portion have recorded health-based violations in recent monitoring periods — placing the county in the lower tier for water safety.
How Jefferson County Compares
How Jefferson County Compares
Jefferson County scores 7 points below the Montana state average (55/100) and 20 points below the national average (68/100).
Data: EPA SDWIS Last verified: 2026-06-03
ZIP Code Risk Map
Water Quality Map: Jefferson County, Montana
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 12.8 (asthma 10.7%, diabetes 10.5%)
Estimated additional annual cost per homeowner: $726, driven primarily by wildfire
Infrastructure: 0.357% avg pipe failure probability, 25% of ZIPs at high risk
49.4% of homes built before 1978 (lead paint era)
Violation History (2021–2026)
→ Stable trendEPA violation counts by year across Jefferson County water systems. Health-based shown in red, total in blue.
Peak year: 2025 with 15 violations. Past 5 years: 46 total (46 health-based).
Source: EPA SDWIS historical violations. Data may lag 6–12 months for the most recent year.
County Health Indicators vs National Average
Black markers indicate national averages. Source: CDC PLACES, Census ACS.
Infrastructure Overview
Sources: Census ACS (housing age), EPA SDWIS (infrastructure risk model), state bridge inspection data.
Compound Risk Breakdown
Estimated additional annual cost per homeowner: $726
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
5,850 housing units in Jefferson County
Source: U.S. Census Bureau ACS B25034 (Year Structure Built).
Water Safety Affordability
How much it costs to fix water issues relative to home values in Jefferson County
Remediation costs are relatively manageable for most homeowners in Jefferson County, representing a small fraction of property value.
Remediation includes water filtration, lead abatement, radon mitigation, and flood protection where applicable. Source: Census ACS, EPA SDWIS.
Health Outcomes vs National Average
CDC PLACES data for Jefferson County residents
Black markers = national averages. Red = above national avg. Green = below. Source: CDC PLACES, Census ACS.
Water Systems with Most Violations
Top 5 systems in Jefferson County ranked by EPA violation count.
| # | Water System | Population | Violations |
|---|---|---|---|
| 1 | WHITEHALL TOWN OF | 1,500 | 22 |
| 2 | Forest Park Water Users Association | 323 | 11 |
| 3 | Saddle Mountain Corporation Clancy | 350 | 11 |
| 4 | Blue Sky Heights Wua Clancy | 250 | 11 |
| 5 | Hangmans Tree Wua | 158 | 11 |
8 total water systems serve Jefferson County.
All ZIP Codes in Jefferson County
8 ZIP codes tracked in Jefferson County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 59631 | Basin | 69 | C | 9 (1 health) | $229K |
| 2 | 59632 | Boulder | 54 | D | 2 (1 health) | $261K |
| 3 | 59634 | Clancy | 52 | D | 11 | $501K |
| 4 | 59759 | Whitehall | 45 | D | 22 (18 health) | $333K |
| 5 | 59638 | Jefferson City | 40 | D | 0 | $269K |
| 6 | 59728 | Elliston | 40 | D | 0 | $397K |
| 7 | 59735 | Harrison | 40 | D | 0 | $420K |
| 8 | 59747 | Pony | 40 | D | 0 | $335K |
Recommended Buyer Guides for Jefferson County
Editorial methodology pairs each documented risk in this county with the buyer category that addresses it, drawing on water-quality detections, housing-stock lead exposure, EPA Radon Zone designation, and FEMA flood and wildfire ratings. NSF-certified options surface where applicable, and products that match the specific contaminant take priority.
- Best Under-Sink Reverse Osmosis Systems — Multi-contaminant removal at the kitchen tap
- Best Radon Test Kits — EPA Radon Zone 1 (highest risk) dominant in county
- Best HEPA Air Purifiers for Wildfire Smoke — Wildfire is the top compound risk factor
Deep Dive Reports
Detailed analysis for Jefferson County, Montana
Overview
Jefferson County in Montana covers 8 ZIP codes with an average Home Safety Score of D (48/100).
4 of 8 ZIP codes have recorded EPA violations. 20 health-based violations have been documented.
← Back to Montana water quality report
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Home values: U.S. Census Bureau ACS (median estimates by ZCTA)
Updated daily.
What You Can Do
Jefferson County has a grade of D. Here are steps to protect your household.
Test your tap water
Order a certified lab test kit ($20-$50) to check for lead, bacteria, and other contaminants specific to your ZIP code.
Consider a certified water filter
NSF-certified filters can remove most common contaminants. Match the filter to your test results for best protection. Try our filter matcher
Contact your water utility
Request the latest Consumer Confidence Report (CCR) from your water provider. It details exactly what was found in your water supply.
Check for lead in your home
49.4% of homes in this county were built before 1978. Older plumbing and solder can leach lead into drinking water, especially in the morning.