Water Quality in LEWISTOWN, MT (59457)

EPA violation data for public water systems serving ZIP code 59457.

182

Total Violations

124

Health-Based

58

Monitoring / Reporting

172

Resolved

What does this mean?

172 of 182 violations have been resolved. 124 are health-based violations, meaning contaminant levels exceeded federal safety limits. The remaining 58 are monitoring or reporting violations (missed testing deadlines or late paperwork — not necessarily a water quality issue). Not all violations mean your water is unsafe. The EPA requires reporting even for minor administrative issues.

Water systems: 35 Population served: 8,433

Violations Detail (182 total)

ContaminantCategoryMCL LimitMeasuredDateStatusHealth Effects
E. COLIMonitoring0N/ANov 10, 2025ResolvedSevere gastrointestinal illness; may be fatal in vulnerable populations
E. COLIMonitoring0N/ANov 10, 2025ResolvedSevere gastrointestinal illness; may be fatal in vulnerable populations
E. COLIMonitoring0N/ANov 10, 2025ResolvedSevere gastrointestinal illness; may be fatal in vulnerable populations
Revised Total Coliform RuleHealth-BasedN/AN/AOct 31, 2025ActiveN/A
Revised Total Coliform RuleHealth-BasedN/AN/AOct 31, 2025ActiveN/A
Nitrate-NitriteHealth-BasedN/A10.7Sep 30, 2025ActiveN/A
Nitrate-NitriteHealth-BasedN/A10.7Sep 30, 2025ActiveN/A
Nitrate-NitriteHealth-BasedN/A10.7Sep 30, 2025ActiveN/A
Nitrate-NitriteHealth-BasedN/A10.7Sep 30, 2025ActiveN/A
Nitrate-NitriteHealth-BasedN/A10.7Sep 30, 2025ActiveN/A

Lead & Copper Levels

Violation Timeline

2025(27)

E. COLI

34

Nov 10Resolved

E. COLI

34

Nov 10Resolved

E. COLI

34

Nov 10Resolved

Revised Total Coliform Rule

2D

Oct 31Active

Revised Total Coliform Rule

2D

Oct 31Active

Nitrate-Nitrite

01

Sep 30Active

Nitrate-Nitrite

01

Sep 30Active

Nitrate-Nitrite

01

Sep 30Active

Nitrate-Nitrite

01

Sep 30Active

Nitrate-Nitrite

01

Sep 30Active

Nitrate-Nitrite

01

Sep 30Active

Consumer Confidence Rule

71

Jun 30Resolved

Consumer Confidence Rule

71

Jun 30Resolved

Nitrate-Nitrite

01

Jun 30Resolved

Nitrate-Nitrite

01

Jun 30Resolved

Nitrate-Nitrite

01

Jun 30Resolved

Nitrate-Nitrite

01

Jun 30Resolved

Nitrate-Nitrite

01

Jun 30Resolved

Nitrate-Nitrite

01

Jun 30Resolved

Consumer Confidence Rule

71

Jun 30Resolved

Consumer Confidence Rule

71

Jun 30Resolved

Nitrate-Nitrite

01

Mar 31Resolved

Nitrate-Nitrite

01

Mar 31Resolved

Nitrate-Nitrite

01

Mar 31Resolved

Nitrate-Nitrite

01

Mar 31Resolved

Nitrate-Nitrite

01

Mar 31Resolved

Nitrate-Nitrite

01

Mar 31Resolved

2024(30)

Nitrate-Nitrite

01

Dec 31Resolved

Nitrate-Nitrite

01

Dec 31Resolved

Nitrate-Nitrite

01

Dec 31Resolved

Nitrate-Nitrite

01

Dec 31Resolved

Nitrate-Nitrite

01

Dec 31Resolved

Nitrate-Nitrite

01

Dec 31Resolved

Lead and Copper Rule

66

Dec 29Active

Nitrate-Nitrite

01

Sep 30Resolved

Nitrate-Nitrite

01

Sep 30Resolved

Nitrate-Nitrite

01

Sep 30Resolved

Nitrate-Nitrite

01

Sep 30Resolved

Nitrate-Nitrite

01

Sep 30Resolved

Nitrate-Nitrite

01

Sep 30Resolved

Nitrate-Nitrite

01

Jun 30Resolved

Nitrate-Nitrite

01

Jun 30Resolved

Nitrate-Nitrite

01

Jun 30Resolved

Nitrate-Nitrite

01

Jun 30Resolved

Nitrate-Nitrite

01

Jun 30Resolved

Nitrate-Nitrite

01

Jun 30Resolved

Nitrate-Nitrite

01

Jun 30Resolved

Consumer Confidence Rule

71

Jun 30Active

Revised Total Coliform Rule

3A

May 31Resolved

Revised Total Coliform Rule

3A

May 31Resolved

Revised Total Coliform Rule

3A

May 31Resolved

Nitrate-Nitrite

01

Mar 31Resolved

Nitrate-Nitrite

01

Mar 31Resolved

Nitrate-Nitrite

01

Mar 31Resolved

Nitrate-Nitrite

01

Mar 31Resolved

Nitrate-Nitrite

01

Mar 31Resolved

Nitrate-Nitrite

01

Mar 31Resolved

How Does This Compare?

LEWISTOWN (59457) has 182 recorded violations, including 124 health-based. 10 remain unresolved. Consider testing your tap water independently for added peace of mind.

Recommended Water Filters

Based on the contaminants detected in your area, these filter types may help improve your water quality.

Reverse Osmosis System

Highly effective at removing heavy metals, dissolved solids, and a wide range of contaminants. Recommended for homes with lead or arsenic concerns.

Targets:Lead, Copper, Arsenic, Mercury, Cadmium

Look for:NSF/ANSI 58 certified

UV Water Purifier

Uses ultraviolet light to neutralize bacteria, viruses, and parasites without chemicals. Ideal for homes with microbial contamination concerns.

Targets:E. coli, Coliform, Giardia, Cryptosporidium

Look for:NSF/ANSI 55 (Class A) certified

Always look for filters certified by NSF International for the specific contaminants you want to remove.

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