| Violation ID |
Occurred Date |
Violation Type |
(-) Violation Description |
Corrective Action |
Status |
Classification |
Source |
| 1155728 |
05/04/2026 |
CAT1 |
UV Dose 1-Hour Average (Mean) limit is 127 mJ/cm2 and reported value was 100 mJ/cm2 at UVS-001. |
The WWTP operators reviewed the SCADA log and determined that although the UV dose below the system setpoint was recorded, no dose alarms were triggered and the system did not automatically start up additional banks as expected. There appears to have been an unexpected period from 5/2/2026 - 5/5/2026 where alarms from the UV system were not working, as no other alarms were triggered during this period. Additionally, the local PLC did not operate as intended to add additional banks into operation. The UV system has operated as expected since this unexplained partial control system outage, for both typical WWTP flows as well as a subsequent large storm event on 5/26/2026. The WWTP operators completed tests on the system, and were unable to recreate this error and confirmed that alarm and control setpoints were appropriate, alarms were triggered, and banks were added to operation as expected. The WWTP operators will continue to closely monitor the system for other issues.
No water quality impacts are expected based on this discharge violation, as the UV System was validated with on-site bioassay testing in 2022 and shown to be effective at a lower UV dose of 100 mJ/cm2. DDW reviewed the results of the study and in May 2023 recommended that the CVRWQCB revise the permit to reduce the minimum UV system dose to 100 mJ/cm2. This reduced minimum hourly average UV dose is currently reflected in the tentative NOA that is expected to be effective October 1, 2026.
|
Violation |
U |
eSMR |
| 1154929 |
04/22/2026 |
DMON |
Total coliform sample for Channel 2 on 4/22/2026 was missed due to sampling error. The lab technician mistakenly collected one sample from a channel that was offline, rather than the two active channels. |
The lab manager reviewed the process to identify active UV channels prior to sampling with the lab technicians. |
Violation |
B |
eSMR |
| 1154930 |
04/18/2026 |
CAT1 |
Nitrite Plus Nitrate (as N) Weekly Average limit is 15 mg/L and reported value was 16 mg/L at EFF-001. |
UC Davis is reviewing sampling schedules to ensure that the typical variation in effluent nitrate levels is captured in the monitoring plan to accurately represent the average weekly and average monthly values used for compliance. |
Violation |
B |
eSMR |
| 1150059 |
11/30/2025 |
CAT1 |
Nitrite Plus Nitrate (as N) Monthly Average (Mean) limit is 10 mg/L and reported value was 12 mg/L at EFF-001. |
The sampling schedule was modified to accurately capture both the weekly and the monthly average conditions, to provide effluent water quality data that is more reflective of conditions specified in the permit. |
Violation |
B |
eSMR |
| 1144379 |
05/27/2025 |
OEV |
Total Coliform 7-Day Median limit is 2.2 MPN/100 mL and reported value was 3.3 MPN/100 mL at UVS-002. |
The WWTP operators were not able to clean the UV channel on the typical PM schedule in May. When the violation occurred, operators switched UV operation to a different channel and cleaned the channel with elevated coliform levels. |
Violation |
B |
eSMR |
| 1143348 |
05/02/2025 |
LREP |
Quarterly SMR ( MONNPDES ) report for Q1 2025 (2463142) was due on 01-MAY-25 |
Facility staff implemented a calendar reminder for all reporting, to avoid a repeat of this type of oversight. |
Violation |
B |
Report |
| 1143384 |
02/19/2025 |
CTOX |
Chronic Toxicity-C.dubia-Reproduction 3-Sample Median limit is 25 % effect and reported value was 57.9 % effect at EFF-001. |
Persistence testing was conducted on the second sample; the results supported a potential pathogen interference but it could not be confirmed. A TIE was initiated, but showed no baseline toxicity and therefore was inconclusive. UC Davis will repeat the TIE efforts with the Q2 routine WET test, in case toxicity is present. |
Violation |
B |
eSMR |
| 1139631 |
12/31/2024 |
CTOX |
Chronic Toxicity 3-Sample Median limit is 25 % effect and reported value was 46 % effect at EFF-001. |
As a corrective action, Utilities staff will work with central cooling plant operators and management to develop a discharge solution for their annual cleaning activities that minimizes impacts to the treatment process and limits the potential for any adverse impact to the environment. Additionally, lab staff will inspect sample equipment prior to the initiation of all toxicity tests. |
Violation |
B |
eSMR |
| 1136555 |
10/19/2024 |
CAT1 |
Biochemical Oxygen Demand (BOD) (5-day @ 20 Deg. C) Weekly Average limit is 15 mg/L and reported value was 16 mg/L at EFF-001. |
Utilities staff believe that the cause of the elevated BOD was process waste from the campus research winery; staff are working on implementing a pretreatment process at the winery to prevent future WWTP process impacts. |
Violation |
B |
eSMR |
| 1135048 |
09/11/2024 |
DMON |
a. The MRP condition IV.A.2.i. requires that ¿effluent samples for temperature, pH, hardness, dissolved oxygen, and dissolved organic carbon shall be taken approximately the same time and on the same date with the receiving water samples for these parameters.¿ The sample for effluent dissolved oxygen was missed when all other listed parameters were collected on 9/11/2024 at both the effluent and receiving water monitoring locations. The issue was not immediately identified, and the effluent DO sampling did not occur until 9/18/2024. |
As a corrective action, the WWTP laboratory team reviewed the sampling requirements and discussed importance to conduct sampling as required by the WDR. Staff also discussed actions if samples were missed in the future, including resampling concurrent sample locations/analytes. |
Violation |
B |
eSMR |
| 1132968 |
08/14/2024 |
DMON |
Effluent ammonia sampling was not completed at the weekly frequency specified by the MRP condition IV.A.1. No sample was collected for the week of August 11th. Staff missed this bottle when collecting samples for the subcontract lab. UC Davis staff did conduct in-house sampling via the HACH TNT method on 8/14/2023 and the result was 0.433 mg/L. The in-house ammonia analysis is just for process control and was not conducted by an approved test procedure under the WDRs, so this value has not been reported to CIWQS or used to determine compliance with the monthly effluent limitations. |
Reviewed sampling requirements with sampling staff, and discussed expectation to conduct sampling as required by the WDR. |
Violation |
B |
eSMR |
| 1132969 |
08/07/2024 |
DMON |
Effluent Dissolved Oxygen monitoring was conducted on a different day than the monthly effluent and receiving water monitoring. MRP condition IV.A.2.i. states that ¿the effluent samples for temperature, pH, hardness, dissolved oxygen, and dissolved organic carbon shall be taken approximately the same time and on the same date with the receiving water samples for these parameters.¿ Effluent DO was missed during sample collection on 8/7/2024, and was instead collected on 8/8/2024. |
Reviewed sampling requirements with sampling staff, and discussed expectation to conduct sampling as required by the WDR. |
Violation |
B |
eSMR |
| 1126367 |
03/30/2024 |
Deficient Reporting |
The Annual Progress Report was due on 2/28/2024 as part of the Compliance Schedule for Final Effluent Limitations for Chronic Toxicity. Due to staff changes and oversight of this reporting requirement, the University requested an extension on 2/16/2024 so that a thorough and useful update could be provided. At the time of the request, University staff were working with sewer system dischargers to understand the cause of past intermittant toxicity. |
Tracking and staffing will support the timely submittal of future reports. |
Violation |
U |
eSMR |
| 1123418 |
12/31/2023 |
CAT1 |
Biochemical Oxygen Demand (BOD) (5-day @ 20 Deg. C) Monthly Average limit is 10.0 mg/L and reported value was 13.0 mg/L at EFF-001. |
No corrective action was taken. BOD and TSS have started to trend down once school went back on session. |
Violation |
B |
eSMR |
| 1123419 |
12/30/2023 |
DMON |
The plant was experiencing high turbidity and the plant was put on diversion for most of the day. The pH and temperature were not measured during the approximate 40-minute window when the laboratory analyst was present due to a misunderstanding. The laboratory analyst thought that the plant was going to be discharging the rest of the day but the turbidity was high that the plant operator on site had to put the plant on diversion into the following morning. |
Better communications will be implemented between operations and laboratory. |
Violation |
B |
eSMR |
| 1117345 |
04/13/2023 |
OEV |
Total Coliform 7-Day Median limit is 2.2 MPN/100 mL and reported value was 4.5 MPN/100 mL at UVS-002. |
Please see email from 4/19/23. |
Violation |
B |
eSMR |
| 1117350 |
04/12/2023 |
OEV |
Total Coliform 7-Day Median limit is 2.2 MPN/100 mL and reported value was 13 MPN/100 mL at UVS-002. |
Please see email from 4/19/23. |
Violation |
B |
eSMR |
| 1117349 |
04/11/2023 |
OEV |
Total Coliform 7-Day Median limit is 2.2 MPN/100 mL and reported value was 13 MPN/100 mL at UVS-002. |
Please see email from 4/19/23. |
Violation |
B |
eSMR |
| 1117348 |
04/06/2023 |
OEV |
Total Coliform 7-Day Median limit is 2.2 MPN/100 mL and reported value was 4.5 MPN/100 mL at UVS-002. |
Please see email from 4/19/23 |
Violation |
B |
eSMR |
| 1117347 |
04/05/2023 |
OEV |
Total Coliform 7-Day Median limit is 2.2 MPN/100 mL and reported value was 4.5 MPN/100 mL at UVS-002. |
Please see email from 4/19/23 |
Violation |
B |
eSMR |
| 1117346 |
04/04/2023 |
OEV |
Total Coliform 7-Day Median limit is 2.2 MPN/100 mL and reported value was 3.25 MPN/100 mL at UVS-002. |
Please see email from 4/19/23 |
Violation |
B |
eSMR |
| 1114661 |
08/06/2022 |
DMON |
Deficient receiving water monitoring for temperature during the first week of August 2022 was due to an instrument operation error by field staff. Proper operation of the field instruments was reviewed when the error was discovered. |
|
Violation |
B |
Report |
| 1108097 |
03/24/2022 |
UAUTHDISC |
On March 24th, 2022 the UC Davis WWTP discharged non-disinfected treated effluent for approximately 1 hour and 19 minutes, from 00:29 to 01 :48. The discharge violation occurred due to a programming error in the new UV system. Channel #2, which was not in service, had an alarm interconnect to Channel #1, which was in service, that turned off the operational banks on Channel #1, causing non-disinfected water to be discharged. |
|
Violation |
B |
Report |
| 1101623 |
12/07/2021 |
CTOX |
Chronic Toxicity Other limit is 16 TUc and reported value was 17 TUc at EFF-001. |
|
Violation |
B |
Report |
| 1101621 |
10/24/2021 |
CAT1 |
UV Dose 1-Hour Average (Mean) limit is 127 mJ/cm2 and reported value was 94 mJ/cm2 at UVS-001. |
|
Violation |
B |
Report |
|
Report displays most recent five years of violations. Refer to the Interactive Violation Report for more data.
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