PRAIRIE ISLAND
NPDES ID: MN0061336
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: 2 reporting violations.
Violations
March 31, 2026
Solids, suspended percent removal
93% over limit
Discharged 71 % against a permitted limit of 85 % (MN % RMV)
DMR, Limited - Numeric Violation
January 31, 2026
Nitrogen, ammonia total [as N]
0% over limit
Discharged 0 mg/L against a permitted limit of 0 mg/L (MO AVG)
DMR, Monitor Only - Overdue
Nitrogen, ammonia total [as N]
0% over limit
Discharged 0 mg/L against a permitted limit of 0 mg/L (DAILY MX)
DMR, Monitor Only - Overdue
July 31, 2025
Solids, suspended percent removal
80% over limit
Discharged 73 % against a permitted limit of 85 % (MN % RMV)
DMR, Limited - Numeric Violation
Oxygen, dissolved [DO]
27% over limit
Discharged 3.65 mg/L against a permitted limit of 5 mg/L (DAILY MN)
DMR, Limited - Numeric Violation
May 31, 2025
Solids, total suspended
87% over limit
Discharged 84 mg/L against a permitted limit of 45 mg/L (WKLY AVG)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 5.85 SU against a permitted limit of 6 SU (MINIMUM)
DMR, Limited - Numeric Violation
April 30, 2025
Oxygen, dissolved [DO]
10% over limit
Discharged 4.51 mg/L against a permitted limit of 5 mg/L (DAILY MN)
DMR, Limited - Numeric Violation
March 31, 2025
Oxygen, dissolved [DO]
13% over limit
Discharged 4.35 mg/L against a permitted limit of 5 mg/L (DAILY MN)
DMR, Limited - Numeric Violation
August 31, 2024
Nitrogen, ammonia total [as N]
0% over limit
Discharged 0 mg/L against a permitted limit of 0 mg/L (MO AVG)
DMR, Monitor Only - Overdue
Nitrogen, ammonia total [as N]
0% over limit
Discharged 0 mg/L against a permitted limit of 0 mg/L (MO AVG)
DMR, Monitor Only - Overdue
Nitrogen, ammonia total [as N]
0% over limit
Discharged 0 mg/L against a permitted limit of 0 mg/L (DAILY MX)
DMR, Monitor Only - Overdue
First flagged
April 14, 2026 (3 months ago)
Last confirmed
July 13, 2026 (23 days ago)