Public water system record
Osu Water Plant
Serves Stillwater, Payne County, OK · 13,000 people served
Federal records show 13 health-based violations and 3 monitoring/reporting issues for Osu Water Plant 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
- 13
- Resolved
- 13
- Unresolved
- 0
- Any acute record
- No
- Monitoring issues, last 10 years
- 3
Key facts
- Osu Water Plant draws water from 2 surface water intakes (1 of them for emergency, seasonal or other part-time use).
- Highest measured level in the last 10 years: Total Trihalomethanes (TTHMs), 0.088 mg/L, federal limit 0.08 mg/L (1.1 times the limit), 2019.
- Most recent formal enforcement: compliance order (no penalty) by Oklahoma, November 2025.
- Record on file since 1987, with 9 health-based violations before October 19, 2016.
- Lead pipe inventory: 0 lead and 0 unknown out of 413 service lines.
Check whether Osu Water Plant 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 0.081 mg/L, federal limit 0.08 mg/L (at or just above the limit)
|
220 | Jul 1, 2025 | Resolved | No |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.082 mg/L, federal limit 0.08 mg/L (at or just above the limit)
|
220 | Apr 1, 2025 | Resolved | No |
|
Surface Water Treatment Rule
Treatment technique failure
|
120 | Mar 1, 2023 | Resolved | No |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.081 mg/L, federal limit 0.08 mg/L (at or just above the limit)
|
220 | Oct 1, 2019 | Resolved | No |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.088 mg/L, federal limit 0.08 mg/L (1.1 times the limit)
|
220 | Apr 1, 2019 | Resolved | No |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.086 mg/L, federal limit 0.08 mg/L (1.1 times the limit)
|
220 | Apr 1, 2019 | Resolved | No |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.088 mg/L, federal limit 0.08 mg/L (1.1 times the limit)
|
220 | Apr 1, 2019 | Resolved | No |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.088 mg/L, federal limit 0.08 mg/L (1.1 times the limit)
|
220 | Jan 1, 2019 | Resolved | No |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.084 mg/L, federal limit 0.08 mg/L (1.1 times the limit)
|
220 | Jan 1, 2019 | Resolved | No |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.084 mg/L, federal limit 0.08 mg/L (1.1 times the limit)
|
220 | Jan 1, 2019 | Resolved | No |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.082 mg/L, federal limit 0.08 mg/L (at or just above the limit)
|
220 | Oct 1, 2018 | Resolved | No |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.085 mg/L, federal limit 0.08 mg/L (1.1 times the limit)
|
220 | Oct 1, 2018 | Resolved | No |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.082 mg/L, federal limit 0.08 mg/L (at or just above the limit)
|
220 | Jul 1, 2018 | 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
|
Jun 30, 2025 | Resolved |
|
Total Trihalomethanes (TTHMs)
Monitoring and reporting
|
Mar 31, 2020 | Resolved |
|
Total Trihalomethanes (TTHMs)
Monitoring and reporting
|
Dec 30, 2019 | Resolved |
Full record since 1987
EPA's records for Osu Water Plant go back to 1987. Before October 19, 2016 they list 9 health-based violations (9 resolved) and 7 monitoring or reporting violations.
| Violations that began in | Health-based | Monitoring and reporting |
|---|---|---|
| 1980s | 3 | 0 |
| 1990s | 2 | 2 |
| 2000s | 1 | 1 |
| 2010 to October 18, 2016 | 3 | 4 |
| October 19, 2016 to 2019 | 10 | 1 |
| 2020s | 3 | 2 |
Most recent health-based violation before October 19, 2016: Total Trihalomethanes (TTHMs), began January 2014, Resolved.
Show all 9 health-based violations before October 19, 2016
| Contaminant | Start date | Status |
|---|---|---|
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.083 mg/L, federal limit 0.08 mg/L (at or just above the limit)
|
Jan 1, 2014 | Resolved |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.088 mg/L, federal limit 0.08 mg/L (1.1 times the limit)
|
Oct 1, 2013 | Resolved |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.088 mg/L, federal limit 0.08 mg/L (1.1 times the limit)
|
Oct 1, 2012 | Resolved |
|
Total Coliform
Contaminant limit exceeded
|
Nov 1, 2008 | Resolved |
|
Total Coliform
Contaminant limit exceeded
|
Oct 1, 1993 | Resolved |
|
Total Coliform
Contaminant limit exceeded
|
Aug 1, 1991 | Resolved |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
|
Aug 1, 1987 | Resolved |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
|
May 1, 1987 | Resolved |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
|
Feb 1, 1987 | Resolved |
Enforcement actions
Oklahoma regulators took 8 formal enforcement actions against Osu Water Plant between 1987 and 2025. The most recent was a compliance order (no penalty) in November 2025.
| Date | By | Action | Violations covered |
|---|---|---|---|
| Nov 19, 2025 | Oklahoma | Compliance order (no penalty) | 1 violation (1 health-based): Total Trihalomethanes (TTHMs) |
| Sep 4, 2025 | Oklahoma | Compliance order (no penalty) | 1 violation (1 health-based): Total Trihalomethanes (TTHMs) |
| Jul 6, 2023 | Oklahoma | Compliance order (no penalty) | 1 violation (1 health-based): Surface Water Treatment Rule |
| Jul 14, 2020 | Oklahoma | Compliance order (no penalty) | 4 violations (4 health-based): Total Trihalomethanes (TTHMs) |
| Apr 11, 2019 | Oklahoma | Compliance order (no penalty) | 6 violations (6 health-based): Total Trihalomethanes (TTHMs) |
| Jun 18, 2014 | Oklahoma | Compliance order with a penalty | 2 violations (2 health-based): Total Trihalomethanes (TTHMs) |
| Apr 30, 2013 | Oklahoma | Compliance order with a penalty | 1 violation (1 health-based): Total Trihalomethanes (TTHMs) |
| Sep 30, 1987 | Oklahoma | Compliance order (no penalty) | 3 violations (3 health-based): Total Trihalomethanes (TTHMs) |
What the violations mean
Total Trihalomethanes (TTHMs)
12 incidentsDisinfection byproduct levels exceeded the federal limit
Long-term TTHM exposure may increase bladder cancer risk
Surface Water Treatment Rule
1 incidentThe system did not complete a treatment step or action that the Surface Water Treatment Rule requires (a treatment technique violation).
The utility had to notify customers about this violation.
Where the water comes from
Osu Water Plant draws water from 2 surface water intakes (1 of them for emergency, seasonal or other part-time use). It also has an emergency connection to Stillwater Utilities Authority.
Emergency or part-time connections to
- Stillwater Utilities Authority Stillwater, OK
Annual water quality report
Osu Water Plant 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 Oklahoma.
Certified drinking water labs by state EPA guidance for private wells