TapSafetyReport
C52/100

ASSINIBOINE & SIOUX RURAL WATER SYSTEM — Water Quality Report 2026

Serving 1,726 people · Montana

Water Source
Surface Water
County
—
System ID
083090050
Violations
12

Contaminant Test Results

1 contaminant above EPA health goals
ContaminantDetectedLimit (MCL)Status
Copper (90th percentile)
2.03 mg/L1.30 mg/LOver Limit

EPA Violation History

4

Violations (last 5yr)

0

Unresolved

0

Health-Related

TIER 3Resolved

Failed Level 2 Assessment under Revised Total Coliform Rule

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2025 – June 30, 2025Rule: Stage 2 DBPREnforcement: Resolving — corrective action underway
TIER 3Resolved

Failed Level 2 Assessment under Revised Total Coliform Rule

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2025 – June 30, 2025Rule: Stage 2 DBPREnforcement: Resolving — corrective action underway
TIER 3Resolved

Failed Level 2 Assessment under Revised Total Coliform Rule

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: September 1, 2023 – November 30, 2023Rule: Stage 2 DBPREnforcement: Resolving — corrective action underway
TIER 3Resolved

Failed Level 2 Assessment under Revised Total Coliform Rule

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: September 1, 2023 – November 30, 2023Rule: Stage 2 DBPREnforcement: Resolving — corrective action underway

Understanding violation severity

Tier 1Urgent health risk. Utility must notify all customers within 24 hours.Tier 2Important health or treatment issue. Customers notified within 30 days.Tier 3Administrative or monitoring issue. Reported in the annual water quality report.

Source: EPA Safe Drinking Water Information System (SDWIS) · Updated quarterly

Frequently Asked Questions About ASSINIBOINE & SIOUX RURAL WATER SYSTEM

Is ASSINIBOINE & SIOUX RURAL WATER SYSTEM water safe to drink?

ASSINIBOINE & SIOUX RURAL WATER SYSTEM water receives a grade of C (52/100), which is considered fair. 1 contaminant(s) exceed EPA legal limits and 12 violation(s) are on record. Customers may want to consider using a water filter.

What contaminants has ASSINIBOINE & SIOUX RURAL WATER SYSTEM detected?

2 contaminants were tested in ASSINIBOINE & SIOUX RURAL WATER SYSTEM's water. Notable contaminants include Copper (90th percentile). 1 exceed EPA legal limits (MCLs). 1 exceed EPA health goals (MCLGs).

Does ASSINIBOINE & SIOUX RURAL WATER SYSTEM have any EPA violations?

Yes, ASSINIBOINE & SIOUX RURAL WATER SYSTEM has 12 EPA violation(s) on record, with the most recent in 2025. Violation types include MR, MON, TT. 7 are health-based violations.

How many people does ASSINIBOINE & SIOUX RURAL WATER SYSTEM serve?

ASSINIBOINE & SIOUX RURAL WATER SYSTEM serves approximately 1,726 people, Montana.

What type of water does ASSINIBOINE & SIOUX RURAL WATER SYSTEM provide?

ASSINIBOINE & SIOUX RURAL WATER SYSTEM sources its water from surface water. Surface water comes from rivers, lakes, or reservoirs and typically requires more extensive treatment. The utility's system ID is 083090050.

How does ASSINIBOINE & SIOUX RURAL WATER SYSTEM compare to other utilities in Montana?

ASSINIBOINE & SIOUX RURAL WATER SYSTEM scores 52/100 with a grade of C (fair). This score indicates room for improvement compared to other utilities. Visit our Montana state page for a full comparison of water systems.