OAK HARBOR WWTP
NPDES ID: OH0026841
E — SNC: Effluent violation (monthly average limit)
The facility discharged more of a pollutant than its permit allows, based on a monthly average.
This quarter: 5 effluent violations.
Violations
May 31, 2026
Nitrogen, ammonia total [as N]
125% over limit
Discharged 7.86 kg/d against a permitted limit of 3.5 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
96% over limit
Discharged 10.4 kg/d against a permitted limit of 5.3 kg/d (WKLY MAX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
158% over limit
Discharged 2.58 mg/L against a permitted limit of 1 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
139% over limit
Discharged 3.58 mg/L against a permitted limit of 1.5 mg/L (WKLY MAX)
DMR, Limited - Numeric Violation
April 30, 2026
Solids, total suspended
1% over limit
Discharged 160 kg/d against a permitted limit of 158 kg/d (WKLY MAX)
DMR, Limited - Numeric Violation
March 31, 2026
Solids, total suspended
5% over limit
Discharged 110 kg/d against a permitted limit of 105 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Solids, total suspended
1% over limit
Discharged 160 kg/d against a permitted limit of 158 kg/d (WKLY MAX)
DMR, Limited - Numeric Violation
October 31, 2025
Nitrogen, ammonia total [as N]
39% over limit
Discharged 2.08 mg/L against a permitted limit of 1.5 mg/L (WKLY MAX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
81% over limit
Discharged 1.81 mg/L against a permitted limit of 1 mg/L (MO AVG)
DMR, Limited - Numeric Violation
September 30, 2025
Nitrogen, ammonia total [as N]
27% over limit
Discharged 1.27 mg/L against a permitted limit of 1 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
17% over limit
Discharged 1.75 mg/L against a permitted limit of 1.5 mg/L (WKLY MAX)
DMR, Limited - Numeric Violation
August 31, 2025
Nitrogen, ammonia total [as N]
63% over limit
Discharged 1.63 mg/L against a permitted limit of 1 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
102% over limit
Discharged 10.7 kg/d against a permitted limit of 5.3 kg/d (WKLY MAX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
51% over limit
Discharged 5.27 kg/d against a permitted limit of 3.5 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
43% over limit
Discharged 2.14 mg/L against a permitted limit of 1.5 mg/L (WKLY MAX)
DMR, Limited - Numeric Violation
July 31, 2025
Nitrogen, ammonia total [as N]
69% over limit
Discharged 2.53 mg/L against a permitted limit of 1.5 mg/L (WKLY MAX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
98% over limit
Discharged 10.5 kg/d against a permitted limit of 5.3 kg/d (WKLY MAX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
73% over limit
Discharged 1.73 mg/L against a permitted limit of 1 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
64% over limit
Discharged 5.75 kg/d against a permitted limit of 3.5 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Solids, total suspended
8% over limit
Discharged 170 kg/d against a permitted limit of 158 kg/d (WKLY MAX)
DMR, Limited - Numeric Violation
June 30, 2025
Nitrogen, ammonia total [as N]
44% over limit
Discharged 1.44 mg/L against a permitted limit of 1 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
43% over limit
Discharged 2.14 mg/L against a permitted limit of 1.5 mg/L (WKLY MAX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
19% over limit
Discharged 4.17 kg/d against a permitted limit of 3.5 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
82% over limit
Discharged 9.67 kg/d against a permitted limit of 5.3 kg/d (WKLY MAX)
DMR, Limited - Numeric Violation
May 31, 2025
Solids, total suspended
5% over limit
Discharged 110 kg/d against a permitted limit of 105 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
153% over limit
Discharged 8.85 kg/d against a permitted limit of 3.5 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
94% over limit
Discharged 10.3 kg/d against a permitted limit of 5.3 kg/d (WKLY MAX)
DMR, Limited - Numeric Violation
Solids, total suspended
1% over limit
Discharged 160 kg/d against a permitted limit of 158 kg/d (WKLY MAX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
27% over limit
Discharged 1.91 mg/L against a permitted limit of 1.5 mg/L (WKLY MAX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
103% over limit
Discharged 2.03 mg/L against a permitted limit of 1 mg/L (MO AVG)
DMR, Limited - Numeric Violation
April 30, 2025
Solids, total suspended
349% over limit
Discharged 710 kg/d against a permitted limit of 158 kg/d (WKLY MAX)
DMR, Limited - Numeric Violation
Solids, total suspended
110% over limit
Discharged 220 kg/d against a permitted limit of 105 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Solids, total suspended
22% over limit
Discharged 55 mg/L against a permitted limit of 45 mg/L (WKLY MAX)
DMR, Limited - Numeric Violation
BOD, carbonaceous [5 day, 20 C]
19% over limit
Discharged 190 kg/d against a permitted limit of 159 kg/d (WKLY MAX)
DMR, Limited - Numeric Violation
March 31, 2025
Solids, total suspended
33% over limit
Discharged 210 kg/d against a permitted limit of 158 kg/d (WKLY MAX)
DMR, Limited - Numeric Violation
Mercury, total low level
146% over limit
Discharged 0.0000886 kg/d against a permitted limit of 0.000036 kg/d (MO AVG)
DMR, Limited - Numeric Violation
February 28, 2025
Solids, total suspended
14% over limit
Discharged 180 kg/d against a permitted limit of 158 kg/d (WKLY MAX)
DMR, Limited - Numeric Violation
October 31, 2024
Nitrogen, ammonia total [as N]
35% over limit
Discharged 4.74 kg/d against a permitted limit of 3.5 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
137% over limit
Discharged 3.55 mg/L against a permitted limit of 1.5 mg/L (WKLY MAX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
199% over limit
Discharged 2.99 mg/L against a permitted limit of 1 mg/L (MO AVG)
DMR, Limited - Numeric Violation
August 31, 2024
Overflows
0% over limit
Discharged 0 occur/d against a permitted limit of 0 occur/d (MO AVG)
DMR, Monitor Only - Overdue
Hardness, total [as CaCO3]
0% over limit
Discharged 0 mg/L against a permitted limit of 0 mg/L (DAILY MX)
DMR, Monitor Only - Overdue
Hardness, total [as CaCO3]
0% over limit
Discharged 0 mg/L against a permitted limit of 0 mg/L (MO AVG)
DMR, Monitor Only - Overdue
Phosphorus, total [as P]
0% over limit
Discharged 0 mg/L against a permitted limit of 0 mg/L (MO AVG)
DMR, Monitor Only - Overdue
Overflows
0% over limit
Discharged 0 occur/d against a permitted limit of 0 occur/d (DAILY MX)
DMR, Monitor Only - Overdue
Phosphorus, total [as P]
0% over limit
Discharged 0 mg/L against a permitted limit of 0 mg/L (DAILY MX)
DMR, Monitor Only - Overdue
Nitrogen, ammonia total [as N]
178% over limit
Discharged 2.78 mg/L against a permitted limit of 1 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Mercury, total low level
73% over limit
Discharged 0.0000621 kg/d against a permitted limit of 0.000036 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Mercury, total low level
161% over limit
Discharged 0.0000269 mg/L against a permitted limit of 0.0000103 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
7% over limit
Discharged 3.74 kg/d against a permitted limit of 3.5 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
133% over limit
Discharged 3.5 mg/L against a permitted limit of 1.5 mg/L (WKLY MAX)
DMR, Limited - Numeric Violation
First flagged
April 14, 2026 (3 months ago)
Last confirmed
August 1, 2026 (5 days ago)