Is Sun River, MT Tap Water Safe to Drink?
Graded A-, with 19 unresolved violations on record. See what was cited — and what it means for your tap. What to do next ↓
86.2/100
waterverge.com Sun River, MT — Water Quality Report
Sun River's drinking water received a grade of A- (86.2 out of 100), indicating good water quality. The city's 2 water systems serve approximately 630 residents using groundwater.
Lead levels were measured at 2.0 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 53 violations on record, including 2 health-based violations. 19 remain unresolved.
What to know about Sun River's water
Sun River ranks #16 out of 115 cities in Montana for water quality, placing it above average in the state.
Sun River relies on groundwater, which is generally less vulnerable to surface contamination but can be affected by naturally occurring minerals like arsenic and nitrate, as well as agricultural and industrial runoff.
As a small community water system, Sun River may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
Water quality score
See methodology →Is Sun River, MT water safe to drink?
Sun River's drinking water has significant quality concerns based on EPA testing data. With a grade of A- (86.2/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 2 water systems serve approximately 630 residents using groundwater (wells).
Recent water quality updates for Sun River
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Sun River's water quality assessment. Grade: A- (86.2/100).
Contaminants: TTHM, Total Haloacetic Acids (HAA5).
Contaminants: Combined Radium (-226 and -228).
Contaminants: Consumer Confidence Rule.
Federal disaster declaration (FEMA DR-3253). Hurricane event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-640). Flood event — may have impacted local water infrastructure.
Key contaminant findings
Based on the most recent EPA sampling data for Sun River's water supply.
Well within EPA limits.
Violation history
Sun River's water system has 53 total violations on record, including 2 health-based violations. 19 remain unresolved.
Flood & environmental risk
Cascade County has experienced 3 federally declared disasters since 1975. Flooding and severe storms can overwhelm water treatment plants, cause sewage overflows, and introduce agricultural runoff, bacteria, and sediment into drinking water supplies. Local water sources include Sun River At Simms.
Where does Sun River's water come from?
Sun River's drinking water comes from groundwater (wells), supplied by 2 water systems serving approximately 630 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate. Nearby water bodies include Sun River At Simms (river).
What Sun River residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Sun River's water.
Your water utility is required to publish an annual Consumer Confidence Report (CCR) with detailed testing results. Ask for the latest copy or check your utility's website.
Sun River's area has a history of flooding. After severe weather, watch for boil water advisories from your local utility.
Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.
Top contaminants to know
View all ↓Violation summary
Violations & advisories
Top industrial polluters within 10 miles of Sun River
Industrial polluters nearby
Reported releases to surface water by facilities near Sun River, ranked by pounds discharged annually.
| Facility | Top chemical | To surface water (lbs/yr) | Distance |
|---|---|---|---|
BIG SKY SCIENTIFIC L.L.C. SUN RIVER, MT59483 | — | — | 0.2 mi |
Source: EPA Toxic Release Inventory (TRI) 2023
Drought conditions
D3 — extreme droughtCascade County is currently in D3 (extreme drought) per the U.S. Drought Monitor (week of May 5, 2026). Drought can elevate disinfection-byproduct (TTHM/HAA5) levels and taste/odor issues as utilities draw from lower reservoirs.
Source: U.S. Drought Monitor, updated weekly by NDMC, USDA, and NOAA.
Flood & disaster history
Cascade County has experienced 3 federally declared disasters since 1975. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
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. | 2.0 | 15 | ppb | Inorganic | Safe |
Lead level trend (90th percentile)
See how Sun River compares by contaminant
Explore where Sun River ranks among all Montana cities for specific contaminants.
Water source & infrastructure
Where Sun River's water comes from
Sun River's drinking water is drawn from underground aquifers through wells.
Groundwater is naturally filtered through rock and soil layers, generally requiring less treatment than surface water. However, it can contain naturally occurring contaminants like arsenic, radon, and minerals.
Agricultural activity, septic systems, and industrial operations near well fields can introduce nitrates, pesticides, and volatile organic compounds.
The system is operated by private ownership and serves approximately 630 people through 2 water systems.
Water bodies near Sun River
Sun River is located near 1 notable water body. These water bodies contribute to the regional watershed and may indirectly affect groundwater quality.
Water systems serving Sun River
| System Name | PWSID | Population | Source |
|---|---|---|---|
| TWO BUTTES WATER USERS ASSN | MT0000580 | 525 | GW |
| CASCADE COLONY | MT0001738 | 105 | GW |
How Sun River compares
Full Montana rankings →Sun River's score of 86.2/100 is above the average of 45/100 among major Montana cities. It outscores 10 of 10 nearby cities.
Nearby cities
View Montana rankings →About Sun River, MT
Learn more about your water
Guides and resources related to Sun River's water quality findings.
Explore water quality across Cascade
Frequently asked questions
Is Sun River, MT tap water safe to drink?
Sun River's water quality earned a grade of A- (86.2/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #16 out of 115 cities tested in Montana.
What contaminants are in Sun River's water?
Lead was measured at 2.0 ppb (90th percentile). 53 violations are on record.
How is Sun River'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 Sun River?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Sun River's water come from?
Sun River's water is sourced from Groundwater. The city has 2 water systems serving approximately 630 residents.
What health violations has Sun River's water system had?
Sun River has 2 health-based violations on record. The most recent violation was recorded in October 2019. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 19 violations remain unresolved.
Is Sun River's groundwater at risk of contamination?
Sun River uses groundwater, which can be affected by naturally occurring contaminants like arsenic, radon, and nitrate, as well as agricultural runoff and industrial activity. The system has 53 violations on record that may relate to groundwater quality. Groundwater systems are generally less susceptible to surface contamination but should be monitored for emerging contaminants like PFAS.
How does Sun River's water compare to other cities?
Sun River ranks #16 out of 115 cities in Montana (better than 86% of state cities) and #4888 out of 15744 cities nationally (69th percentile). The grade of A- reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.