MONONA CITY OF STP
NPDES ID: IA0036927
X — SNC: Effluent violation (non-monthly average limit)
The facility discharged more of a pollutant than its permit allows, measured over a period other than a monthly average.
Violations
February 28, 2026
Nitrogen, ammonia total [as N]
12% over limit
Discharged 4.15 mg/L against a permitted limit of 3.7 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
57% over limit
Discharged 10.62225153 kg/d against a permitted limit of 6.76459994 kg/d (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
172% over limit
Discharged 16.6 mg/L against a permitted limit of 6.1 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
December 31, 2025
Nitrogen, ammonia total [as N]
142% over limit
Discharged 8.47 mg/L against a permitted limit of 3.5 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
37% over limit
Discharged 2.8725 mg/L against a permitted limit of 2.1 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
December 31, 2024
pH
0% over limit
Discharged 6.4 SU against a permitted limit of 6.5 SU (DAILY MN)
DMR, Limited - Numeric Violation
August 31, 2024
Nitrogen, ammonia total [as N]
75% over limit
Discharged 5.78 mg/L against a permitted limit of 3.3 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
78% over limit
Discharged 1.7775 mg/L against a permitted limit of 1 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
15% over limit
Discharged 1.30000856 kg/d against a permitted limit of 1.13499999 kg/d (30DA AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
13% over limit
Discharged 3.96121398 kg/d against a permitted limit of 3.49579997 kg/d (DAILY MX)
DMR, Limited - Numeric Violation
First flagged
April 14, 2026 (3 months ago)
Last confirmed
July 13, 2026 (24 days ago)