01The verdict: is Colstrip water safe?
Colstrip's tap water meets most EPA standards but has areas that warrant attention. With a grade of A- (85.2/100), some contaminant levels or compliance issues suggest that residents may benefit from additional filtration. The city's 1 water system serves approximately 2,350 residents using surface water (rivers, lakes, or reservoirs).
2 unresolved violations on record
EPA records show open compliance items for this system. Most are administrative, but unresolved items are worth watching.
See what was cited ↓Lead is well under the limit
90th-percentile lead is 1.0 ppb — beneath the 15 ppb federal action level and under the 5 ppb watch threshold.
See the trend ↓8 violations in the last five years
Recent compliance history is the best predictor of future problems — the year-by-year record is below.
See the record ↓Colstrip's drinking water received a grade of A- (85.2 out of 100), indicating good water quality. The city's 1 water system serves approximately 2,350 residents using surface water.
Lead levels were measured at 1.0 ppb (90th percentile), well within EPA limits. This system has not yet been tested for PFAS under the EPA UCMR 5 program. The system has 56 violations on record, including 2 health-based violations. 2 remain unresolved.
Colstrip ranks #16 out of 110 cities in Montana for water quality, placing it above average in the state. The city draws from surface water sources, which are more susceptible to seasonal runoff and agricultural contamination, requiring extensive multi-barrier treatment including coagulation, filtration, and disinfection. As a small community water system, Colstrip may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities. The system has seen 8 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
02What's in Colstrip's water
Every contaminant flagged in Colstrip, on one shared scale: distance to its own legal limit. The red line is the limit — anything past it is out of compliance, and the closer a bar gets, the less headroom the system has.
Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 1.0 | 15 | ppb | Inorganic | Safe |
Cities ranked by 90th-percentile lead PF PFAS in Montana
Cities ranked by compounds detected Cu Copper in Montana
Cities ranked by 90th-percentile copper
03Colstrip's ten-year track record
Each box is one year. A green check means no EPA violations; a numbered badge counts that year's violations — red if any were health-based, amber if they were monitoring or paperwork issues. The system has 56 violations on record, including 2 health-based violations. 2 remain unresolved.
7 of the last ten years were clean. The numbered years had EPA violations — red when any were health-based, amber when they were paperwork or missed-testing issues.
▼ Down 14 ppb since 1993. Latest reading: 1 ppb (2025) — 7% of the action level. Sampled at higher-risk homes (90th percentile).
04Where Colstrip's water comes from
Colstrip's drinking water comes primarily from surface water sources such as rivers, lakes, or reservoirs.
Surface Water
Rivers, lakes, or reservoirs — more exposed to runoff, agriculture, and seasonal swings than groundwater.
Local treatment
Multi-barrier treatment: coagulation, sedimentation, filtration, and disinfection to meet EPA standards.
1 system
1 water system, operated under local government ownership.
2,350 people
Residents served across Colstrip's service area.
Surface water systems require multi-stage treatment including coagulation, sedimentation, filtration, and disinfection to meet EPA Safe Drinking Water Act standards. These sources can be impacted by seasonal changes, stormwater runoff, upstream agriculture, and industrial discharge. The system is operated by local government ownership and serves approximately 2,350 people through 1 water system.
| System name | PWSID | Population | Source |
|---|---|---|---|
| COLSTRIP CITY OF | MT0000180 | 2,350 | Surface Water |
05Pressure on Colstrip's watershed
Outside forces that shape what reaches the treatment plant. None of these is a verdict on the tap by itself — but each adds pressure worth knowing about.
Industrial discharge
2 facilities within 10 miles reported 0 lb released to surface water in the latest EPA Toxics Release Inventory. Proximity doesn't equal tap contamination — treatment and hydrology decide — but it's pressure on the watershed.
Flood & storm history
5 federal disaster declarations on record for Rosebud County. Flooding and severe storms can overwhelm treatment plants, cause sewage overflows, and push runoff into supplies.
Drought
Rosebud County is in D2 (severe drought) per the U.S. Drought Monitor (week of Jul 2026). Drought can raise disinfection-byproduct levels and taste/odor issues as utilities draw from lower reservoirs.
06How Colstrip compares
Scores for nearby Montana cities on one line, with the average marked.
dashed line = Montana average (48/100)
Colstrip scores 85.2/100 — above the Montana average of 48/100. It outscores 10 of 10 nearby cities. Full Montana rankings →
39.6 / 100FMissoula, MT
42.6 / 100FBozeman, MT
43.4 / 100FGreat Falls, MT
34.5 / 100FKalispell, MT
40.1 / 100FHelena, MT
39.1 / 100
Compare all cities in the county — grades, violations, and contaminant data side by side.→
07What to do at home
Steps matched to what testing actually found in Colstrip's water — not generic advice.
A basic carbon filter still helps
Colstrip's water meets federal standards, but a simple carbon filter improves taste and adds a margin of safety against short-term issues.
Compare tested filters →Read your utility's annual report
Every utility must publish a yearly Consumer Confidence Report with its own testing results. It pairs well with the independent data on this page.
How to read a CCR →Watch for Colstrip alerts
This area has a history of flood declarations — after severe weather, watch for boil-water advisories from the utility, and check the live alerts on this page.
All water alerts →Frequently asked questions
Is Colstrip, MT tap water safe to drink?
Colstrip's water quality earned a grade of A- (85.2/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #16 out of 110 cities tested in Montana.
What contaminants are in Colstrip's water?
Lead was measured at 1.0 ppb (90th percentile). 56 violations are on record.
How is Colstrip's water quality grade calculated?
The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.
Do I need a water filter in Colstrip?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Colstrip's water come from?
Colstrip's water is sourced from Surface water. The city has 1 water system serving approximately 2,350 residents.
What health violations has Colstrip's water system had?
Colstrip has 2 health-based violations on record. The most recent violation was recorded in July 2024. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 2 violations remain unresolved.
How does Colstrip's water compare to other cities?
Colstrip ranks #16 out of 110 cities in Montana (better than 85% of state cities) and #5417 out of 15382 cities nationally (65th percentile). The grade of A- reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does Colstrip's small water system affect quality?
Colstrip's system serves approximately 2,350 residents. Small community water systems (under 3,300 people) may have fewer financial resources for infrastructure upgrades and advanced treatment technologies. However, they are held to the same EPA drinking water standards as larger systems. This system has 56 violations on record.