Public water system record
Sioux City Water Supply
Serves Sioux City, Woodbury County, IA · 85,791 people served
Federal records show 4 health-based violations and 2 monitoring/reporting issues for Sioux City Water Supply in the last ten years. The most serious issue in this window was a resolved Total Trihalomethanes (TTHMs) violation.
System profile
- Health-based violations, last 10 years
- 4
- Resolved
- 4
- Unresolved
- 0
- Any acute record
- No
- Monitoring issues, last 10 years
- 2
Key facts
- Sioux City Water Supply draws water from 8 wells and 3 infiltration galleries.
- Highest measured level in the last 10 years: Total Trihalomethanes (TTHMs), 0.084 mg/L, federal limit 0.08 mg/L (1.1 times the limit), 2019.
- Most recent formal enforcement: signed compliance agreement by Iowa, April 2001.
- Record on file since 1979, with 10 health-based violations before October 19, 2016.
- Lead pipe inventory: 4,271 lead and 2,587 unknown out of 25,645 service lines.
Check whether Sioux City Water Supply serves your address
Health-based violations
Since October 2016Violation data reflects EPA records through March 2026. For the most current status, visit the EPA ECHO database.
| Contaminant | Rule family | Start date | Status | Acute |
|---|---|---|---|---|
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.084 mg/L, federal limit 0.08 mg/L (1.1 times the limit)
|
220 | Oct 1, 2019 | Resolved | No |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.083 mg/L, federal limit 0.08 mg/L (at or just above the limit)
|
220 | Jul 1, 2019 | Resolved | No |
|
Epichlorohydrin
Treatment technique failure
|
320 | Mar 6, 2017 | Resolved | No |
|
Epichlorohydrin
Treatment technique failure
|
320 | Nov 25, 2016 | Resolved | No |
Monitoring and reporting issues
Since October 2016Missed tests or reports, not contaminants found above a limit.
| Issue | Start date | Status |
|---|---|---|
|
Total Trihalomethanes (TTHMs)
Monitoring and reporting
|
May 1, 2024 | Resolved |
|
Haloacetic Acids (HAA5)
Monitoring and reporting
|
May 1, 2024 | Resolved |
Full record since 1979
EPA's records for Sioux City Water Supply go back to 1979. Before October 19, 2016 they list 10 health-based violations (8 resolved, 2 archived by EPA without a recorded fix) and 18 monitoring or reporting violations.
| Violations that began in | Health-based | Monitoring and reporting |
|---|---|---|
| 1970s | 2 | 0 |
| 1990s | 3 | 2 |
| 2000s | 3 | 13 |
| 2010 to October 18, 2016 | 2 | 3 |
| October 19, 2016 to 2019 | 4 | 0 |
| 2020s | 0 | 2 |
Most recent health-based violation before October 19, 2016: Epichlorohydrin, began May 2016, Resolved.
Show all 10 health-based violations before October 19, 2016
| Contaminant | Start date | Status |
|---|---|---|
|
Epichlorohydrin
Treatment technique failure
|
May 19, 2016 | Resolved |
|
Surface Water Treatment Rule
Treatment technique failure
|
Apr 1, 2012 | Resolved |
|
Interim Enhanced Surface Water Treatment Rule (acute)
Treatment technique failure
|
Nov 1, 2004 | Resolved |
|
Interim Enhanced Surface Water Treatment Rule (acute)
Treatment technique failure
|
Apr 1, 2004 | Resolved |
|
Surface Water Treatment Rule
Treatment technique failure
|
Mar 1, 2004 | Resolved |
|
Total Coliform (acute)
Contaminant limit exceeded
|
Aug 1, 1997 | Resolved |
|
Total Coliform (acute)
Contaminant limit exceeded
|
Jun 1, 1996 | Resolved |
|
Total Coliform
Contaminant limit exceeded
|
Jun 1, 1991 | Resolved |
|
Combined Radium (-226 and -228)
Contaminant limit exceeded
|
Jul 24, 1979 | Archived |
|
Combined Radium (-226 and -228)
Contaminant limit exceeded
|
Jul 24, 1979 | Archived |
Enforcement actions
Iowa regulators took 2 formal enforcement actions against Sioux City Water Supply in 2001, filed as 4 records in EPA's data. The most recent was a signed compliance agreement in April 2001.
| Date | By | Action | Violations covered |
|---|---|---|---|
| Apr 19, 2001 | Iowa | Signed compliance agreement | 1 violation: Miscellaneous Other Rules |
| Mar 7, 2001 | Iowa | Consent decree or court judgment | 3 violations: Miscellaneous Other Rules |
What the violations mean
Total Trihalomethanes (TTHMs)
2 incidentsDisinfection byproduct levels exceeded the federal limit
Long-term TTHM exposure may increase bladder cancer risk
Epichlorohydrin
2 incidentsThe system did not complete a treatment step or action that federal rules require for Epichlorohydrin (a treatment technique violation).
The utility had to notify customers about each of these violations.
Where the water comes from
Sioux City Water Supply draws water from 8 wells and 3 infiltration galleries. 2 other community water systems buy water from Sioux City Water Supply.
Community systems that buy water from it
- City of South Sioux City South Sioux City, NE
- Dakota Dunes Cid Dakota Dunes, SD
Annual water quality report
Sioux City Water Supply must give its customers an annual water quality report (Consumer Confidence Report) by July 1, with the levels its tests found in the previous year.
Systems serving 10,000 or more people must mail or deliver the report to every customer, and from 2027 they must send it twice a year.
Find a posted report with EPA's Consumer Confidence Report search
Testing your own water
To test the water at your tap, or a private well this record does not cover, use a laboratory certified for drinking water by Iowa.
Certified drinking water labs by state EPA guidance for private wells