SOUTHWESTERN SENIOR HIGH SCHOOL STP
NPDES ID: IL0045641
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: 4 effluent violations.
Violations
May 31, 2026
Nitrogen, ammonia total [as N]
67% over limit
Discharged 2.5 mg/L against a permitted limit of 1.5 mg/L (MO AVG)
DMR, Limited - Numeric Violation
April 30, 2026
Oxygen, dissolved [DO]
37% over limit
Discharged 3.8 mg/L against a permitted limit of 6 mg/L (MN WK AV)
DMR, Limited - Numeric Violation
Oxygen, dissolved [DO]
24% over limit
Discharged 3.8 mg/L against a permitted limit of 5 mg/L (DAILY MN)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
83% over limit
Discharged 2.74 mg/L against a permitted limit of 1.5 mg/L (MO AVG)
DMR, Limited - Numeric Violation
March 31, 2026
Nitrogen, ammonia total [as N]
49% over limit
Discharged 2.23 mg/L against a permitted limit of 1.5 mg/L (MO AVG)
DMR, Limited - Numeric Violation
February 28, 2026
Nitrogen, ammonia total [as N]
1% over limit
Discharged 0.3632 kg/d against a permitted limit of 0.35866 kg/d (MO AVG)
DMR, Limited - Numeric Violation
BOD, carbonaceous [5 day, 20 C]
30% over limit
Discharged 13 mg/L against a permitted limit of 10 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Solids, total suspended
75% over limit
Discharged 21 mg/L against a permitted limit of 12 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Oxygen, dissolved [DO]
32% over limit
Discharged 3.75 mg/L against a permitted limit of 5.5 mg/L (MO AV MN)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
1270% over limit
Discharged 37 mg/L against a permitted limit of 2.7 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Oxygen, dissolved [DO]
6% over limit
Discharged 3.75 mg/L against a permitted limit of 4 mg/L (MN WK AV)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
487% over limit
Discharged 37 mg/L against a permitted limit of 6.3 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
January 31, 2026
Nitrogen, ammonia total [as N]
74% over limit
Discharged 4.7 mg/L against a permitted limit of 2.7 mg/L (MO AVG)
DMR, Limited - Numeric Violation
December 31, 2025
Nitrogen, ammonia total [as N]
41% over limit
Discharged 3.8 mg/L against a permitted limit of 2.7 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Oxygen, dissolved [DO]
7% over limit
Discharged 5.1 mg/L against a permitted limit of 5.5 mg/L (MO AV MN)
DMR, Limited - Numeric Violation
November 30, 2025
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
Nitrogen, ammonia total [as N]
144% over limit
Discharged 6.6 mg/L against a permitted limit of 2.7 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
5% over limit
Discharged 6.6 mg/L against a permitted limit of 6.3 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
October 31, 2025
Nitrogen, ammonia total [as N]
350% over limit
Discharged 13.5 mg/L against a permitted limit of 3 mg/L (DAILY MX)
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
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
Nitrogen, ammonia total [as N]
800% over limit
Discharged 13.5 mg/L against a permitted limit of 1.5 mg/L (MO AVG)
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
September 30, 2025
Nitrogen, ammonia total [as N]
280% over limit
Discharged 5.7 mg/L against a permitted limit of 1.5 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
90% over limit
Discharged 5.7 mg/L against a permitted limit of 3 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
August 31, 2025
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
Oxygen, dissolved [DO]
0% over limit
Discharged 0 mg/L against a permitted limit of 4 mg/L (MN WK AV)
DMR, Limited - Overdue
Flow, in conduit or thru treatment plant
0% over limit
Discharged 0 MGD against a permitted limit of 0 MGD (DAILY MX)
DMR, Monitor Only - Overdue
Flow, in conduit or thru treatment plant
0% over limit
Discharged 0 MGD against a permitted limit of 0 MGD (MO AVG)
DMR, Monitor Only - Overdue
Solids, total suspended
0% over limit
Discharged 0 kg/d against a permitted limit of 1.589 kg/d (MO AVG)
DMR, Limited - Overdue
Oxygen, dissolved [DO]
0% over limit
Discharged 0 mg/L against a permitted limit of 5.5 mg/L (MO AV MN)
DMR, Limited - Overdue
BOD, carbonaceous [5 day, 20 C]
0% over limit
Discharged 0 kg/d against a permitted limit of 1.3166 kg/d (MO AVG)
DMR, Limited - Overdue
Flow, in conduit or thru treatment plant
0% over limit
Discharged 0 MGD against a permitted limit of 0 MGD (DAILY MX)
DMR, Monitor Only - Overdue
Solids, total suspended
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 kg/d against a permitted limit of 0.39952 kg/d (DAILY MX)
DMR, Limited - Overdue
Flow, in conduit or thru treatment plant
0% over limit
Discharged 0 MGD against a permitted limit of 0 MGD (MO AVG)
DMR, Monitor Only - Overdue
Solids, total suspended
0% over limit
Discharged 0 mg/L against a permitted limit of 24 mg/L (DAILY MX)
DMR, Limited - Overdue
pH
0% over limit
Discharged 0 SU against a permitted limit of 9 SU (MAXIMUM)
DMR, Limited - Overdue
Oxygen, dissolved [DO]
0% over limit
Discharged 0 mg/L against a permitted limit of 3.5 mg/L (DAILY MN)
DMR, Limited - Overdue
BOD, carbonaceous [5 day, 20 C]
0% over limit
Discharged 0 mg/L against a permitted limit of 20 mg/L (DAILY MX)
DMR, Limited - Overdue
Nitrogen, ammonia total [as N]
0% over limit
Discharged 0 kg/d against a permitted limit of 0.1589 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 2.6332 kg/d (DAILY MX)
DMR, Limited - Overdue
Nitrogen, ammonia total [as N]
0% over limit
Discharged 0 mg/L against a permitted limit of 3 mg/L (DAILY MX)
DMR, Limited - Overdue
BOD, 5-day, 20 deg. C
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 1.2 mg/L (MO AVG)
DMR, Limited - Overdue
Coliform, fecal general
0% over limit
Discharged 0 MPN/100mL against a permitted limit of 0 MPN/100mL (DAILY MX)
DMR, Monitor Only - Overdue
Chlorine, total residual
0% over limit
Discharged 0 mg/L against a permitted limit of 0.05 mg/L (DAILY MX)
DMR, Limited - Overdue
pH
0% over limit
Discharged 0 SU against a permitted limit of 6 SU (MINIMUM)
DMR, Limited - Overdue
Solids, total suspended
0% over limit
Discharged 0 mg/L against a permitted limit of 12 mg/L (MO AVG)
DMR, Limited - Overdue
Solids, total suspended
0% over limit
Discharged 0 kg/d against a permitted limit of 3.178 kg/d (DAILY MX)
DMR, Limited - Overdue
July 31, 2025
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
Nitrogen, ammonia total [as N]
0% over limit
Discharged 0 kg/d against a permitted limit of 0.39952 kg/d (DAILY MX)
DMR, Limited - Overdue
Oxygen, dissolved [DO]
0% over limit
Discharged 0 mg/L against a permitted limit of 5 mg/L (DAILY MN)
DMR, Limited - Overdue
BOD, carbonaceous [5 day, 20 C]
0% over limit
Discharged 0 mg/L against a permitted limit of 20 mg/L (DAILY MX)
DMR, Limited - Overdue
Nitrogen, ammonia total [as N]
0% over limit
Discharged 0 mg/L against a permitted limit of 3 mg/L (DAILY MX)
DMR, Limited - Overdue
Nitrogen, ammonia total [as N]
0% over limit
Discharged 0 kg/d against a permitted limit of 0.1589 kg/d (MO AVG)
DMR, Limited - Overdue
Flow, in conduit or thru treatment plant
0% over limit
Discharged 0 MGD against a permitted limit of 0 MGD (MO AVG)
DMR, Monitor Only - Overdue
BOD, carbonaceous [5 day, 20 C]
0% over limit
Discharged 0 kg/d against a permitted limit of 1.3166 kg/d (MO AVG)
DMR, Limited - Overdue
Flow, in conduit or thru treatment plant
0% over limit
Discharged 0 MGD against a permitted limit of 0 MGD (MO AVG)
DMR, Monitor Only - Overdue
Solids, total suspended
0% over limit
Discharged 0 kg/d against a permitted limit of 3.178 kg/d (DAILY MX)
DMR, Limited - Overdue
Oxygen, dissolved [DO]
0% over limit
Discharged 0 mg/L against a permitted limit of 6 mg/L (MN WK AV)
DMR, Limited - Overdue
BOD, 5-day, 20 deg. C
0% over limit
Discharged 0 mg/L against a permitted limit of 0 mg/L (MO AVG)
DMR, Monitor Only - Overdue
Flow, in conduit or thru treatment plant
0% over limit
Discharged 0 MGD against a permitted limit of 0 MGD (DAILY MX)
DMR, Monitor Only - Overdue
Solids, total suspended
0% over limit
Discharged 0 mg/L against a permitted limit of 12 mg/L (MO AVG)
DMR, Limited - Overdue
Solids, total suspended
0% over limit
Discharged 0 kg/d against a permitted limit of 1.589 kg/d (MO AVG)
DMR, Limited - Overdue
Flow, in conduit or thru treatment plant
0% over limit
Discharged 0 MGD against a permitted limit of 0 MGD (DAILY MX)
DMR, Monitor Only - Overdue
BOD, carbonaceous [5 day, 20 C]
0% over limit
Discharged 0 kg/d against a permitted limit of 2.6332 kg/d (DAILY MX)
DMR, Limited - Overdue
Nitrogen, ammonia total [as N]
0% over limit
Discharged 0 mg/L against a permitted limit of 1.2 mg/L (MO AVG)
DMR, Limited - Overdue
Coliform, fecal general
0% over limit
Discharged 0 MPN/100mL against a permitted limit of 0 MPN/100mL (DAILY MX)
DMR, Monitor Only - Overdue
Chlorine, total residual
0% over limit
Discharged 0 mg/L against a permitted limit of 0.05 mg/L (DAILY MX)
DMR, Limited - Overdue
pH
0% over limit
Discharged 0 SU against a permitted limit of 6 SU (MINIMUM)
DMR, Limited - Overdue
Solids, total suspended
0% over limit
Discharged 0 mg/L against a permitted limit of 0 mg/L (MO AVG)
DMR, Monitor Only - Overdue
pH
0% over limit
Discharged 0 SU against a permitted limit of 9 SU (MAXIMUM)
DMR, Limited - Overdue
Solids, total suspended
0% over limit
Discharged 0 mg/L against a permitted limit of 24 mg/L (DAILY MX)
DMR, Limited - Overdue
June 30, 2025
BOD, carbonaceous [5 day, 20 C]
0% over limit
Discharged 0 mg/L against a permitted limit of 20 mg/L (DAILY MX)
DMR, Limited - Overdue
Solids, total suspended
0% over limit
Discharged 0 mg/L against a permitted limit of 24 mg/L (DAILY MX)
DMR, Limited - Overdue
Flow, in conduit or thru treatment plant
0% over limit
Discharged 0 MGD against a permitted limit of 0 MGD (DAILY MX)
DMR, Monitor Only - Overdue
Chlorine, total residual
0% over limit
Discharged 0 mg/L against a permitted limit of 0.05 mg/L (DAILY MX)
DMR, Limited - Overdue
Solids, total suspended
0% over limit
Discharged 0 mg/L against a permitted limit of 12 mg/L (MO AVG)
DMR, Limited - Overdue
Flow, in conduit or thru treatment plant
0% over limit
Discharged 0 MGD against a permitted limit of 0 MGD (MO AVG)
DMR, Monitor Only - Overdue
Nitrogen, ammonia total [as N]
0% over limit
Discharged 0 kg/d against a permitted limit of 0.39952 kg/d (DAILY MX)
DMR, Limited - Overdue
Flow, in conduit or thru treatment plant
0% over limit
Discharged 0 MGD against a permitted limit of 0 MGD (DAILY MX)
DMR, Monitor Only - Overdue
pH
0% over limit
Discharged 0 SU against a permitted limit of 6 SU (MINIMUM)
DMR, Limited - Overdue
BOD, carbonaceous [5 day, 20 C]
0% over limit
Discharged 0 kg/d against a permitted limit of 1.3166 kg/d (MO AVG)
DMR, Limited - Overdue
pH
0% over limit
Discharged 0 SU against a permitted limit of 9 SU (MAXIMUM)
DMR, Limited - Overdue
Nitrogen, ammonia total [as N]
0% over limit
Discharged 0 kg/d against a permitted limit of 0.1589 kg/d (MO AVG)
DMR, Limited - Overdue
Solids, total suspended
0% over limit
Discharged 0 kg/d against a permitted limit of 3.178 kg/d (DAILY MX)
DMR, Limited - Overdue
Solids, total suspended
0% over limit
Discharged 0 mg/L against a permitted limit of 0 mg/L (MO AVG)
DMR, Monitor Only - 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
Flow, in conduit or thru treatment plant
0% over limit
Discharged 0 MGD against a permitted limit of 0 MGD (MO AVG)
DMR, Monitor Only - Overdue
BOD, carbonaceous [5 day, 20 C]
0% over limit
Discharged 0 kg/d against a permitted limit of 2.6332 kg/d (DAILY MX)
DMR, Limited - Overdue
Nitrogen, ammonia total [as N]
0% over limit
Discharged 0 mg/L against a permitted limit of 3 mg/L (DAILY MX)
DMR, Limited - Overdue
Oxygen, dissolved [DO]
0% over limit
Discharged 0 mg/L against a permitted limit of 6 mg/L (MN WK AV)
DMR, Limited - Overdue
Solids, total suspended
0% over limit
Discharged 0 kg/d against a permitted limit of 1.589 kg/d (MO AVG)
DMR, Limited - Overdue
Coliform, fecal general
0% over limit
Discharged 0 MPN/100mL against a permitted limit of 0 MPN/100mL (DAILY MX)
DMR, Monitor Only - Overdue
Nitrogen, ammonia total [as N]
0% over limit
Discharged 0 mg/L against a permitted limit of 1.2 mg/L (MO AVG)
DMR, Limited - Overdue
Oxygen, dissolved [DO]
0% over limit
Discharged 0 mg/L against a permitted limit of 5 mg/L (DAILY MN)
DMR, Limited - Overdue
BOD, 5-day, 20 deg. C
0% over limit
Discharged 0 mg/L against a permitted limit of 0 mg/L (MO AVG)
DMR, Monitor Only - Overdue
April 30, 2025
Nitrogen, ammonia total [as N]
193% over limit
Discharged 8.8 mg/L against a permitted limit of 3 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
487% over limit
Discharged 8.8 mg/L against a permitted limit of 1.5 mg/L (MO AVG)
DMR, Limited - Numeric Violation
March 31, 2025
Solids, total suspended
8% over limit
Discharged 13 mg/L against a permitted limit of 12 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
130% over limit
Discharged 8.5 mg/L against a permitted limit of 3.7 mg/L (WKLY AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
77% over limit
Discharged 8.5 mg/L against a permitted limit of 4.8 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
467% over limit
Discharged 8.5 mg/L against a permitted limit of 1.5 mg/L (MO AVG)
DMR, Limited - Numeric Violation
February 28, 2025
Solids, total suspended
125% over limit
Discharged 27 mg/L against a permitted limit of 12 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Solids, total suspended
13% over limit
Discharged 27 mg/L against a permitted limit of 24 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
January 31, 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
December 31, 2024
Nitrogen, ammonia total [as N]
67% over limit
Discharged 4.5 mg/L against a permitted limit of 2.7 mg/L (MO AVG)
DMR, Limited - Numeric Violation
November 30, 2024
Nitrogen, ammonia total [as N]
93% over limit
Discharged 5.2 mg/L against a permitted limit of 2.7 mg/L (MO AVG)
DMR, Limited - Numeric Violation
October 31, 2024
Nitrogen, ammonia total [as N]
553% over limit
Discharged 9.8 mg/L against a permitted limit of 1.5 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
227% over limit
Discharged 9.8 mg/L against a permitted limit of 3 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
September 30, 2024
Nitrogen, ammonia total [as N]
97% over limit
Discharged 5.9 mg/L against a permitted limit of 3 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
293% over limit
Discharged 5.9 mg/L against a permitted limit of 1.5 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
2% over limit
Discharged 0.4086 kg/d against a permitted limit of 0.39952 kg/d (DAILY MX)
DMR, Limited - Numeric Violation
Solids, total suspended
25% over limit
Discharged 15 mg/L against a permitted limit of 12 mg/L (MO AVG)
DMR, Limited - Numeric Violation
First flagged
April 14, 2026 (3 months ago)
Last confirmed
July 13, 2026 (23 days ago)