HELENA WWTP
NPDES ID: OH0139050
E — SNC: Effluent violation (monthly average limit)
The facility discharged more of a pollutant than its permit allows, based on a monthly average.
Violations
March 31, 2026
Nitrogen, ammonia total [as N]
216% over limit
Discharged 14.2 mg/L against a permitted limit of 4.5 mg/L (WKLY MAX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
373% over limit
Discharged 14.2 mg/L against a permitted limit of 3 mg/L (MO AVG)
DMR, Limited - Numeric Violation
January 31, 2026
Nitrogen, ammonia total [as N]
613% over limit
Discharged 21.4 mg/L against a permitted limit of 3 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
376% over limit
Discharged 21.4 mg/L against a permitted limit of 4.5 mg/L (WKLY MAX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
42% over limit
Discharged 0.648 kg/d against a permitted limit of 0.455 kg/d (MO AVG)
DMR, Limited - Numeric Violation
July 31, 2025
E. coli, MTEC-MF
8421% over limit
Discharged 24200 MPN/100mL against a permitted limit of 284 MPN/100mL (WK GEOMN)
DMR, Limited - Numeric Violation
E. coli, MTEC-MF
19106% over limit
Discharged 24200 MPN/100mL against a permitted limit of 126 MPN/100mL (MO GEOMN)
DMR, Limited - Numeric Violation
April 30, 2025
Solids, total suspended
83% over limit
Discharged 22 mg/L against a permitted limit of 12 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Solids, total suspended
22% over limit
Discharged 22 mg/L against a permitted limit of 18 mg/L (WKLY MAX)
DMR, Limited - Numeric Violation
March 31, 2025
BOD, carbonaceous [5 day, 20 C]
167% over limit
Discharged 40 mg/L against a permitted limit of 15 mg/L (WKLY MAX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
633% over limit
Discharged 22 mg/L against a permitted limit of 3 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
389% over limit
Discharged 22 mg/L against a permitted limit of 4.5 mg/L (WKLY MAX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
82% over limit
Discharged 0.83 kg/d against a permitted limit of 0.455 kg/d (MO AVG)
DMR, Limited - Numeric Violation
BOD, carbonaceous [5 day, 20 C]
300% over limit
Discharged 40 mg/L against a permitted limit of 10 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
22% over limit
Discharged 0.83 kg/d against a permitted limit of 0.682 kg/d (WKLY MAX)
DMR, Limited - Numeric Violation
February 28, 2025
Solids, total suspended
17% over limit
Discharged 14 mg/L against a permitted limit of 12 mg/L (MO AVG)
DMR, Limited - Numeric Violation
BOD, carbonaceous [5 day, 20 C]
107% over limit
Discharged 31 mg/L against a permitted limit of 15 mg/L (WKLY MAX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
509% over limit
Discharged 27.4 mg/L against a permitted limit of 4.5 mg/L (WKLY MAX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
129% over limit
Discharged 1.04 kg/d against a permitted limit of 0.455 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
813% over limit
Discharged 27.4 mg/L against a permitted limit of 3 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
52% over limit
Discharged 1.04 kg/d against a permitted limit of 0.682 kg/d (WKLY MAX)
DMR, Limited - Numeric Violation
BOD, carbonaceous [5 day, 20 C]
210% over limit
Discharged 31 mg/L against a permitted limit of 10 mg/L (MO AVG)
DMR, Limited - Numeric Violation
September 30, 2024
Flow, in conduit or thru treatment plant
0% over limit
Discharged 0.0579 MGD against a permitted limit of 0 MGD (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
Oxygen, dissolved [DO]
0% over limit
Discharged 7.2 mg/L against a permitted limit of 6 mg/L (DAILY MN)
DMR, Limited - Overdue
BOD, carbonaceous [5 day, 20 C]
0% over limit
Discharged 0 kg/d against a permitted limit of 2.28 kg/d (WKLY MAX)
DMR, Limited - Overdue
BOD, carbonaceous [5 day, 20 C]
0% over limit
Discharged 0 mg/L against a permitted limit of 15 mg/L (WKLY MAX)
DMR, Limited - Overdue
Solids, total suspended
22% over limit
Discharged 22 mg/L against a permitted limit of 18 mg/L (WKLY MAX)
DMR, Limited - Overdue
Solids, total suspended
22% over limit
Discharged 22 mg/L against a permitted limit of 18 mg/L (WKLY MAX)
DMR, Limited - Numeric Violation
Solids, total suspended
0% over limit
Discharged 0.83 kg/d against a permitted limit of 2.73 kg/d (WKLY MAX)
DMR, Limited - Overdue
Nitrogen, ammonia total [as N]
0% over limit
Discharged 0.0076 kg/d against a permitted limit of 0.228 kg/d (WKLY MAX)
DMR, Limited - Overdue
BOD, carbonaceous [5 day, 20 C]
0% over limit
Discharged 0 mg/L against a permitted limit of 10 mg/L (MO AVG)
DMR, Limited - Overdue
pH
0% over limit
Discharged 7.1 SU against a permitted limit of 6.5 SU (DAILY MN)
DMR, Limited - Overdue
Overflows
0% over limit
Discharged 0 occur/d against a permitted limit of 0 occur/d (MO AVG)
DMR, Monitor Only - Overdue
Temperature, water deg. centigrade
0% over limit
Discharged 17 deg C against a permitted limit of 0 deg C (DAILY MX)
DMR, Monitor Only - Overdue
Nitrogen, ammonia total [as N]
0% over limit
Discharged 0.2 mg/L against a permitted limit of 1 mg/L (MO AVG)
DMR, Limited - Overdue
Nitrogen, ammonia total [as N]
0% over limit
Discharged 0.0076 kg/d against a permitted limit of 0.152 kg/d (MO AVG)
DMR, Limited - Overdue
Solids, total suspended
83% over limit
Discharged 22 mg/L against a permitted limit of 12 mg/L (MO AVG)
DMR, Limited - Overdue
Solids, total suspended
83% over limit
Discharged 22 mg/L against a permitted limit of 12 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Turbidity [severity]
0% over limit
Discharged 0 severity against a permitted limit of 0 severity (MO AVG)
DMR, Monitor Only - Overdue
Turbidity [severity]
0% over limit
Discharged 0 severity against a permitted limit of 0 severity (DAILY MX)
DMR, Monitor Only - Overdue
Nitrogen, ammonia total [as N]
0% over limit
Discharged 0.2 mg/L against a permitted limit of 1.5 mg/L (WKLY MAX)
DMR, Limited - Overdue
E. coli, MTEC-MF
0% over limit
Discharged 0 MPN/100mL against a permitted limit of 126 MPN/100mL (MO GEOMN)
DMR, Limited - Overdue
Flow, in conduit or thru treatment plant
0% over limit
Discharged 0.24 MGD against a permitted limit of 0 MGD (DAILY MX)
DMR, Monitor Only - Overdue
Solids, total suspended
0% over limit
Discharged 0.83 kg/d against a permitted limit of 1.82 kg/d (MO AVG)
DMR, Limited - Overdue
BOD, carbonaceous [5 day, 20 C]
0% over limit
Discharged 0 kg/d against a permitted limit of 1.52 kg/d (MO AVG)
DMR, Limited - Overdue
Temperature, water deg. centigrade
0% over limit
Discharged 14 deg C against a permitted limit of 0 deg C (MO AVG)
DMR, Monitor Only - Overdue
E. coli, MTEC-MF
0% over limit
Discharged 0 MPN/100mL against a permitted limit of 284 MPN/100mL (WK GEOMN)
DMR, Limited - Overdue
pH
0% over limit
Discharged 7.1 SU against a permitted limit of 9 SU (DAILY MX)
DMR, Limited - Overdue
August 31, 2024
Nitrogen, ammonia total [as N]
293% over limit
Discharged 5.9 mg/L against a permitted limit of 1.5 mg/L (WKLY MAX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
490% over limit
Discharged 5.9 mg/L against a permitted limit of 1 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
45% over limit
Discharged 0.22 kg/d against a permitted limit of 0.152 kg/d (MO AVG)
DMR, Limited - Numeric Violation
First flagged
April 14, 2026 (3 months ago)
Last confirmed
July 13, 2026 (23 days ago)