Big Arm, MT: High Radon Risk — 40/100 (2026)
1 ZIP code · 1 water system · Updated 2026-06-03
Water compliance in Big Arm, MT ranks below average — documented gaps in multiple service areas.
How Big Arm Compares
Data: EPA SDWIS Last verified: 2026-06-03
Big Arm Water: The Quick Version
- Homes built before 1986: 29% — older plumbing may contain lead solder.
- Estimated remediation: $1,200 per household.
- CDC health risk index: 14.03 — above typical levels.
Water Systems Serving Big Arm
Supply infrastructure in Big Arm, MT runs through a single dominant provider — the main entity among 1 tracked system through which rate decisions, infrastructure work, and federal compliance are managed.
Overview
We track water quality and home safety data for 1 ZIP code in Big Arm, Montana, covering 1 community water system serving approximately 605 people.
No EPA violations recorded across any ZIP codes in Big Arm — an excellent indicator of water quality.
Home Safety Score
Average Home Safety Score for Big Arm: D (40/100)
The score combines three factors:
| Factor | What It Measures |
|---|---|
| Water Quality | EPA violations and compliance history |
| Lead Levels | 90th percentile lead concentration vs EPA action level |
| Radon Risk | EPA radon zone classification |
Water Sources
Big Arm water systems draw from: Groundwater.
Lead & Copper
- Lead data: not yet available for Big Arm
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 1 (High Risk)
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
Areas with No Violations
| ZIP Code | Safety Score | System | Population |
|---|---|---|---|
| 59910 | D | SHELTER BAY ESTATES | 56 |
All ZIP Codes in Big Arm
- 59910 [D]
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Lead/copper: EPA Lead and Copper Rule sampling data
- Radon: EPA Map of Radon Zones
Updated daily.
CDC Health Data for Big Arm
Source: CDC PLACES (County-level estimates). Water contamination can correlate with respiratory and chronic health conditions.
Compared to National Average
Vertical line = national average. ■ Above national · ■ Below national
How Old Is Big Arm's Housing Stock?
Housing age data helps assess potential lead pipe and infrastructure risks. Newer housing stock generally means lower plumbing-related contamination risk.
Source: U.S. Census Bureau American Community Survey (ACS).
Housing Age Profile
Congress banned lead solder in residential plumbing in 1986, drawing a clear line in housing risk by era. Big Arm's median build year of 1995 puts most of its residential stock on the newer side of that boundary — a profile that generally correlates with lower plumbing-sourced lead exposure across the city.
Most homes in Big Arm were built after 1986, reducing the risk of lead contamination from plumbing. Older homes should still be tested.
Source: U.S. Census Bureau ACS B25034.
Big Arm: Remediation Cost in Perspective
Because property values in Big Arm comfortably exceed estimated remediation costs, the equity impact here is proportionally small.
Remediation costs in Big Arm are relatively low compared to home values. The $800–$1,500 estimated range is a small fraction of median property value. Home values are 105% above the Montana average.
Protecting Children from Lead in Big Arm
Why children are most at risk: The CDC states there is no safe level of lead exposure for children. Children under 6 absorb lead more readily than adults, and even low levels can cause developmental delays, learning difficulties, and behavioral problems.
29% of housing in Big Arm predates the federal action against lead solder — a contained share — and aggregate readings stay beneath the regulatory benchmark. Lead therefore sits in a quiet position on the local water-quality picture, with single-home draws as the standard tool for confirming any one address.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
What You Can Do in Big Arm
- Test your water at home. City-level data shows averages — your tap may differ. NSF-certified test kits cost $20-40 and give results in days.
- Install a certified water filter. An NSF-certified pitcher or under-sink filter removes most common contaminants.
- Check your home's plumbing. Homes built before 1986 may have lead solder in pipes. A licensed plumber can assess your risk.
- Review your water system's CCR. Your utility publishes an annual Consumer Confidence Report with detailed test results. Request it or find it online.
Deep Dive Reports
Detailed analysis for Big Arm, MT