A86/100
BIG SIOUX COMMUNITY WATER SYSTEM — Water Quality Report 2026
Serving 5,800 people · South Dakota
Water Source
Groundwater
County
—
System ID
SD4600429
Violations
3
Contaminant Test Results
2 contaminants above EPA health goals
| Contaminant | Detected | Limit (MCL) | Status |
|---|---|---|---|
Copper (90th percentile) | 1.36 mg/L | 1.30 mg/L | Over Limit |
Lead (90th percentile) | 0.001 mg/L | 0.015 mg/L | Above Goal |
EPA Violation History
1
Violation (last 5yr)
0
Unresolved
0
Health-Related
TIER 3Resolved
Exceeded the MCL for disinfection byproducts
This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.
When: July 1, 2021 – September 30, 2021Enforcement: 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 BIG SIOUX COMMUNITY WATER SYSTEM
Is BIG SIOUX COMMUNITY WATER SYSTEM water safe to drink?
BIG SIOUX COMMUNITY WATER SYSTEM water receives a grade of A (86/100), which is considered excellent. Out of 70 contaminants tested, 1 exceed EPA legal limits. 2 contaminant(s) exceed non-enforceable health goals. The water meets federal safety standards.
What contaminants has BIG SIOUX COMMUNITY WATER SYSTEM detected?
70 contaminants were tested in BIG SIOUX COMMUNITY WATER SYSTEM's water. Notable contaminants include Copper (90th percentile), Lead (90th percentile). 1 exceed EPA legal limits (MCLs). 2 exceed EPA health goals (MCLGs).
Does BIG SIOUX COMMUNITY WATER SYSTEM have any EPA violations?
Yes, BIG SIOUX COMMUNITY WATER SYSTEM has 3 EPA violation(s) on record, with the most recent in 2021. Violation types include MR.
How many people does BIG SIOUX COMMUNITY WATER SYSTEM serve?
BIG SIOUX COMMUNITY WATER SYSTEM serves approximately 5,800 people, South Dakota. The system provides water to 1 community: Egan.
What type of water does BIG SIOUX COMMUNITY WATER SYSTEM provide?
BIG SIOUX COMMUNITY WATER SYSTEM sources its water from groundwater. Groundwater is pumped from underground aquifers, which often provides natural filtration. The utility's system ID is SD4600429.
How does BIG SIOUX COMMUNITY WATER SYSTEM compare to other utilities in South Dakota?
BIG SIOUX COMMUNITY WATER SYSTEM scores 86/100 with a grade of A (excellent). This places it among the higher-performing utilities in the state. Visit our South Dakota state page for a full comparison of water systems.