City of Colstrip
EPA ID: MT0000180 · 2,350 people served · 2 ZIP codes
EPA compliance records for City of Colstrip show 1 unresolved violation — findings that remain open and are tracked at the federal level, covering a service territory of approximately 2,350 people.
Data: EPA SDWIS Last verified: 2026-04-02
Service Area Map
Coverage area for City of Colstrip Source: EPA SDWIS service area boundaries.
Service area boundary — Grade D
Service Area Demographics
The City of Colstrip serves a community with a median household income of $73,094 and an estimated 3,100 residents across its service area. Approximately 63% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
Environmental Justice Note: 75% of the population in this service area is classified as disadvantaged under EPA's EJScreen criteria. Communities with higher disadvantaged populations often face disproportionate environmental and health burdens, including aging water infrastructure and limited resources for remediation.
🌊 Where Does Your Water Come From?
City of Colstrip's water is drawn from rivers, lakes, or reservoirs. Surface water sources are more exposed to agricultural runoff, stormwater, and upstream discharges, but they typically receive more intensive treatment before reaching your tap.
About 4% of homes in Big Horn County, Montana rely on private wells rather than public water systems. Private well owners are responsible for their own water testing and treatment.
Infrastructure Risk
Detected Contaminants
How City of Colstrip compares to EPA limits
What This Means For You
Haloacetic Acids (HAA5) at 1 mg/L exceeds the EPA maximum of 0.06 mg/L. Cancer risk; reproductive & developmental effects. Consider granular activated carbon (GAC) filtration.
Total Trihalomethanes (TTHM) at 1 mg/L exceeds the EPA maximum of 0.08 mg/L. Bladder & rectal cancer risk; reproductive concerns. Consider granular activated carbon (GAC) filtration.
E. coli at 2 Zero tolerance (any positive sample triggers immediate action) exceeds the EPA maximum of Zero tolerance (any positive sample triggers immediate action). Severe GI illness; potentially fatal kidney failure in children. Consider UV disinfection (99.99%) filtration.
Consumer Confidence Report Rule at 1 mg/L exceeds the EPA maximum of mg/L.
Haloacetic Acids (HAA5) was detected in this water system. granular activated carbon (GAC) filtration can reduce exposure.
Find a certified water filter →Comparable Water Systems
Similar-sized systems in Montana
Estimated Remediation Costs
Average estimated costs across ZIP codes served by this system
Based on national averages for common remediation projects. Actual costs vary by property. Only issues flagged by EPA, FEMA, or state data for each ZIP code are included.
System Overview
COLSTRIP CITY OF (EPA ID: MT0000180) is a community water system in Montana that serves approximately 2,350 people from surface water sources.
This system provides water to 2 ZIP codes across 2 communities.
Average Home Safety Score: D (53/100)
Based on water quality violations, lead levels, and radon risk across all ZIP codes served by this system.
Violation History
Recent Violations
| Date | Contaminant | Type | Status |
|---|---|---|---|
| July 1, 2024 | E. coli | Health-based | Unresolved |
| July 1, 2024 | Haloacetic Acids (HAA5) | Health-based | Resolved |
| January 1, 2024 | E. coli | Monitoring | Resolved |
| July 1, 2023 | Total Trihalomethanes (TTHM) | Monitoring | Resolved |
Contaminants Detected
The following contaminants have been flagged in EPA records for this water system:
| Contaminant | Category | Violations | Health-Based |
|---|---|---|---|
| E. coli | Microbiological | 2 | Yes |
| Total Trihalomethanes (TTHM) | Disinfection Byproducts | 1 | No |
| Haloacetic Acids (HAA5) | Disinfection Byproducts | 1 | Yes |
| Consumer Confidence Report Rule | Reporting Failure | 1 | No |
Health Risk Details
E. coli (EPA limit: Zero tolerance (any positive sample triggers immediate action))
Severe GI illness; potentially fatal kidney failure in children At-risk groups: children under 5, elderly, immunocompromised individuals, pregnant women.
Removal methods: UV disinfection (99.99%), chlorination, reverse osmosis. Find the right filter →
Haloacetic Acids (HAA5) (EPA limit: 0.06 mg/L)
Cancer risk; reproductive & developmental effects At-risk groups: pregnant women, infants, long-term consumers of chlorinated municipal water.
Removal methods: granular activated carbon (GAC), carbon block filter, reverse osmosis. Find the right filter →
Lead & Copper
EPA Lead and Copper Rule sampling data for ZIP codes served by this system:
| ZIP Code | Lead Level | Exceeds Limit | Sample Date |
|---|---|---|---|
| 59323 | 0.001 mg/L | No | N/A |
Radon Risk in Service Area
Dominant radon zone for ZIP codes served by this system: Zone 1 (High Risk)
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
Need help with your water quality?
Typical cost: Water test: typically $20–$50 (DIY kit) · Professional inspection: $150–$400
Find the Right Water FilterFree tip: Let cold water run for 2 minutes before drinking — this helps flush lead from your pipes.
ZIP Codes Served
Coverage: 1 ZIP code confirmed via EPA Community Water System Service Area Boundaries v3 plus 1 additional ZIP inferred from SDWIS registry data. The EPA-confirmed set is the most reliable; SDWIS-inferred entries may be narrower than the real deployment area.
Data Sources
This report uses public data from the EPA Safe Drinking Water Information System (SDWIS). View the full compliance record for City of Colstrip (MT0000180) on EPA.gov.
Frequently Asked Questions
Is City of Colstrip water safe to drink?
City of Colstrip has recorded 2 health-based violations in the past 5 years. While the system is required to treat water to meet federal standards, you may want to consider additional precautions such as a certified water filter.
How many people does City of Colstrip serve?
City of Colstrip serves approximately 2,350 people across 2 ZIP codes in Montana.
Where does City of Colstrip get its water?
The primary water source is surface water.
Water Source & Treatment
Where this water originates and how it's treated before reaching your tap.
Source: Colstrip City of Consumer Confidence Report.
ZipCheckup is not affiliated with this water utility. Treatment and source data are sourced from the utility's published CCR filings.
Treatment regime
How this utility classifies its treatment process and what each reported treatment chemical does.
Treatment chemicals and what each one does
Chemical names are reported verbatim by the utility. Purpose categories are ZipCheckup annotations based on standard drinking-water treatment practice.
Watershed exposure sources reported
Land-use and natural conditions identified in the utility's source-water assessment as potential contamination sources upstream of treatment.
Treatment classification and chemical list sourced from Colstrip City of Consumer Confidence Report.
Treatment intensity is a ZipCheckup-derived classification based on the chemicals and processes the utility reports. Chemicals and contamination sources are taken verbatim from the utility's CCR filing. Routine federal monitoring and contaminant testing shown elsewhere on this page determine whether the water meets safety standards, not the treatment classification.
Lead Service Line Inventory
Service line breakdown reported under the federal Lead and Copper Rule Improvements (LCRI) inventory requirement:
This system reports zero confirmed lead service lines in its inventory. Unknown-material counts may still warrant verification.
Federal LCRI rule (effective October 2024) requires every public water system to inventory its service lines and complete lead-line replacement within 10 years.
Source: EPA SDWIS Federal Service Line Inventory (Phase 2) · Submitted 2026
ZipCheckup is not affiliated with the utility or state agency. Inventory figures render verbatim from the public LCRI submission cited above; ZipCheckup does not perform inspections or replacements.
Notable events and violations
This section summarizes events the utility chose to disclose in its most recent Consumer Confidence Report, plus any federal compliance violations the utility recorded against itself. Both lists are utility-authored — ZipCheckup does not audit, judge, or reorder them.
Federal compliance violations on record
These entries are taken verbatim from the utility's CCR violations section. EPA defines four broad violation categories: Maximum Contaminant Level (MCL), Treatment Technique (TT), Monitoring & Reporting (M&R), and Public Notification (PN).
-
monitoring2024-01-01/2024-01-31
Failed to test drinking water for contaminant and period indicated; cannot be sure of water quality during the period.
-
treatment technique2024-07-01/2024-07-31
Measurements of disinfectant indicate that adequate disinfection did not occur for the period indicated.
-
MCL · Total Trihalomethanes (TTHM)2024-07-01/2024-09-30
Water samples showed TTHM above maximum contaminant level (MCL) for the period indicated.
Violations record from Colstrip City of Consumer Confidence Report.
ZipCheckup note: items above reflect what the utility published in its most recent CCR. Federal violation records are also tracked separately by the EPA Safe Drinking Water Information System (SDWIS) — the SDWIS record is the authoritative federal source for any specific regulatory action.
Frequently Asked Questions
What You Can Do
Test your water
Home test kits can detect lead, bacteria, and other contaminants at your tap. Find the right filter →
Check your specific ZIP code
Water quality can vary within a system. View nearest ZIP report →
Contact your utility
City of Colstrip (EPA ID: MT0000180) — request the latest Consumer Confidence Report or ask about specific contaminants.