COWDEN STP
NPDES ID: IL0028231
S — SNC: Compliance schedule violation
The facility missed a deadline in its compliance schedule by more than 90 days.
Violations
August 31, 2025
Solids, total suspended
20% over limit
Discharged 36 mg/L against a permitted limit of 30 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Oxygen, dissolved [DO]
62% over limit
Discharged 2.1 mg/L against a permitted limit of 5.5 mg/L (MO AV MN)
DMR, Limited - Numeric Violation
Oxygen, dissolved [DO]
48% over limit
Discharged 2.1 mg/L against a permitted limit of 4 mg/L (MN WK AV)
DMR, Limited - Numeric Violation
Oxygen, dissolved [DO]
40% over limit
Discharged 2.1 mg/L against a permitted limit of 3.5 mg/L (DAILY MN)
DMR, Limited - Numeric Violation
Coliform, fecal general
Limit violation
Discharged 2420 MPN/100mL against a permitted limit of 400 MPN/100mL (DAILY MX)
DMR, Limited - Numeric Violation
July 31, 2025
Coliform, fecal general
Limit violation
Discharged 2420 MPN/100mL against a permitted limit of 400 MPN/100mL (DAILY MX)
DMR, Limited - Numeric Violation
Oxygen, dissolved [DO]
72% over limit
Discharged 1.4 mg/L against a permitted limit of 5 mg/L (DAILY MN)
DMR, Limited - Numeric Violation
Oxygen, dissolved [DO]
77% over limit
Discharged 1.4 mg/L against a permitted limit of 6 mg/L (MN WK AV)
DMR, Limited - Numeric Violation
June 30, 2025
BOD, 5-day, 20 deg. C
10% over limit
Discharged 33 mg/L against a permitted limit of 30 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Coliform, fecal general
505% over limit
Discharged 2420 MPN/100mL against a permitted limit of 400 MPN/100mL (DAILY MX)
DMR, Limited - Numeric Violation
BOD, carbonaceous [5 day, 20 C]
32% over limit
Discharged 33 mg/L against a permitted limit of 25 mg/L (MO AVG)
DMR, Limited - Numeric Violation
May 31, 2025
Coliform, fecal general
Limit violation
Discharged 2420 MPN/100mL against a permitted limit of 400 MPN/100mL (DAILY MX)
DMR, Limited - Numeric Violation
February 28, 2025
Solids, total suspended
40% over limit
Discharged 42 mg/L against a permitted limit of 30 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Solids, total suspended
14% over limit
Discharged 42 mg/L against a permitted limit of 37 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Oxygen, dissolved [DO]
10% over limit
Discharged 3.6 mg/L against a permitted limit of 4 mg/L (MN WK AV)
DMR, Limited - Numeric Violation
Oxygen, dissolved [DO]
35% over limit
Discharged 3.6 mg/L against a permitted limit of 5.5 mg/L (MO AV MN)
DMR, Limited - Numeric Violation
January 31, 2025
BOD, 5-day, 20 deg. C
57% over limit
Discharged 47 mg/L against a permitted limit of 30 mg/L (MO AVG)
DMR, Limited - Numeric Violation
BOD, 5-day, 20 deg. C
4% over limit
Discharged 47 mg/L against a permitted limit of 45 mg/L (WKLY AVG)
DMR, Limited - Numeric Violation
Oxygen, dissolved [DO]
58% over limit
Discharged 1.7 mg/L against a permitted limit of 4 mg/L (MN WK AV)
DMR, Limited - Numeric Violation
Oxygen, dissolved [DO]
51% over limit
Discharged 1.7 mg/L against a permitted limit of 3.5 mg/L (DAILY MN)
DMR, Limited - Numeric Violation
Solids, total suspended
7% over limit
Discharged 48 mg/L against a permitted limit of 45 mg/L (WKLY AVG)
DMR, Limited - Numeric Violation
Solids, total suspended
7% over limit
Discharged 48 mg/L against a permitted limit of 45 mg/L (WKLY AVG)
DMR, Limited - Numeric Violation
BOD, carbonaceous [5 day, 20 C]
88% over limit
Discharged 47 mg/L against a permitted limit of 25 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Solids, total suspended
30% over limit
Discharged 48 mg/L against a permitted limit of 37 mg/L (MO AVG)
DMR, Limited - Numeric Violation
BOD, carbonaceous [5 day, 20 C]
18% over limit
Discharged 47 mg/L against a permitted limit of 40 mg/L (WKLY AVG)
DMR, Limited - Numeric Violation
Oxygen, dissolved [DO]
69% over limit
Discharged 1.7 mg/L against a permitted limit of 5.5 mg/L (MO AV MN)
DMR, Limited - Numeric Violation
Solids, total suspended
60% over limit
Discharged 48 mg/L against a permitted limit of 30 mg/L (MO AVG)
DMR, Limited - Numeric Violation
December 31, 2024
Oxygen, dissolved [DO]
84% over limit
Discharged 0.9 mg/L against a permitted limit of 5.5 mg/L (MO AV MN)
DMR, Limited - Numeric Violation
Oxygen, dissolved [DO]
78% over limit
Discharged 0.9 mg/L against a permitted limit of 4 mg/L (MN WK AV)
DMR, Limited - Numeric Violation
Oxygen, dissolved [DO]
74% over limit
Discharged 0.9 mg/L against a permitted limit of 3.5 mg/L (DAILY MN)
DMR, Limited - Numeric Violation
October 31, 2024
Coliform, fecal general
505% over limit
Discharged 2420 MPN/100mL against a permitted limit of 400 MPN/100mL (DAILY MX)
DMR, Limited - Numeric Violation
Coliform, fecal general
505% over limit
Discharged 2420 MPN/100mL against a permitted limit of 400 MPN/100mL (DAILY MX)
DMR, Limited - Numeric Violation
September 30, 2024
Solids, total suspended
67% over limit
Discharged 50 mg/L against a permitted limit of 30 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Solids, total suspended
35% over limit
Discharged 50 mg/L against a permitted limit of 37 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Oxygen, dissolved [DO]
24% over limit
Discharged 4.2 mg/L against a permitted limit of 5.5 mg/L (MO AV MN)
DMR, Limited - Numeric Violation
Solids, total suspended
11% over limit
Discharged 50 mg/L against a permitted limit of 45 mg/L (WKLY AVG)
DMR, Limited - Numeric Violation
Solids, total suspended
11% over limit
Discharged 50 mg/L against a permitted limit of 45 mg/L (WKLY AVG)
DMR, Limited - Numeric Violation
Coliform, fecal general
Limit violation
Discharged 2420 MPN/100mL against a permitted limit of 400 MPN/100mL (DAILY MX)
DMR, Limited - Numeric Violation
August 31, 2024
Oxygen, dissolved [DO]
56% over limit
Discharged 2.4 mg/L against a permitted limit of 5.5 mg/L (MO AV MN)
DMR, Limited - Numeric Violation
Coliform, fecal general
Limit violation
Discharged 2420 MPN/100mL against a permitted limit of 400 MPN/100mL (DAILY MX)
DMR, Limited - Numeric Violation
Oxygen, dissolved [DO]
42% over limit
Discharged 2.04 mg/L against a permitted limit of 3.5 mg/L (DAILY MN)
DMR, Limited - Numeric Violation
Oxygen, dissolved [DO]
40% over limit
Discharged 2.4 mg/L against a permitted limit of 4 mg/L (MN WK AV)
DMR, Limited - Numeric Violation
First flagged
April 14, 2026 (3 months ago)
Last confirmed
August 1, 2026 (5 days ago)