MITCHELLVILLE CITY OF STP
NPDES ID: IA0021997
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: 1 effluent violation.
Violations
April 30, 2026
Nitrogen, ammonia total [as N]
177% over limit
Discharged 4.159 mg/L against a permitted limit of 1.5 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
March 31, 2026
Nitrogen, ammonia total [as N]
17% over limit
Discharged 3.98125 mg/L against a permitted limit of 3.4 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
Solids, total suspended
40% over limit
Discharged 63 mg/L against a permitted limit of 45 mg/L (7 DA AVG)
DMR, Limited - Numeric Violation
Copper, total [as Cu]
12% over limit
Discharged 0.0302 mg/L against a permitted limit of 0.0269 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
January 31, 2026
Chloride [as Cl]
0% over limit
Discharged 0 mg/L against a permitted limit of 389 mg/L (30DA AVG)
DMR, Limited - Overdue
Chloride [as Cl]
0% over limit
Discharged 0 mg/L against a permitted limit of 629 mg/L (DAILY MX)
DMR, Limited - Overdue
Chloride [as Cl]
0% over limit
Discharged 0 kg/d against a permitted limit of 4023.80196619 kg/d (DAILY MX)
DMR, Limited - Overdue
Chloride [as Cl]
0% over limit
Discharged 0 kg/d against a permitted limit of 2487.0119791 kg/d (30DA AVG)
DMR, Limited - Overdue
December 31, 2025
Copper, total [as Cu]
147% over limit
Discharged 0.04174 mg/L against a permitted limit of 0.01687 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
16% over limit
Discharged 18.6 mg/L against a permitted limit of 16 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Copper, total [as Cu]
301% over limit
Discharged 0.108 mg/L against a permitted limit of 0.0269 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Chloride [as Cl]
5% over limit
Discharged 410 mg/L against a permitted limit of 389 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
268% over limit
Discharged 9.204 mg/L against a permitted limit of 2.5 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
Solids, total suspended
6% over limit
Discharged 31.8 mg/L against a permitted limit of 30 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
November 30, 2025
Chloride [as Cl]
0% over limit
Discharged 0 kg/d against a permitted limit of 4023.80196619 kg/d (DAILY MX)
DMR, Limited - Overdue
Chloride [as Cl]
0% over limit
Discharged 0 mg/L against a permitted limit of 389 mg/L (30DA AVG)
DMR, Limited - Overdue
Chloride [as Cl]
0% over limit
Discharged 0 kg/d against a permitted limit of 2487.0119791 kg/d (30DA AVG)
DMR, Limited - Overdue
Chloride [as Cl]
0% over limit
Discharged 0 mg/L against a permitted limit of 629 mg/L (DAILY MX)
DMR, Limited - Overdue
October 31, 2025
Toxicity [acute], Ceriodaphnia dubia
0% over limit
Discharged 0 pass=0;fail=1 against a permitted limit of 1 pass=0;fail=1 (DAILY MX)
DMR, Limited - Overdue
Solids, total suspended
0% over limit
Discharged 0 kg/d against a permitted limit of 192.04199839 kg/d (30DA AVG)
DMR, Limited - Overdue
Nitrogen, ammonia total [as N]
0% over limit
Discharged 0 kg/d against a permitted limit of 9.94259992 kg/d (30DA AVG)
DMR, Limited - Overdue
BOD, carbonaceous [5 day, 20 C]
0% over limit
Discharged 0 mg/L against a permitted limit of 40 mg/L (7 DA AVG)
DMR, Limited - Overdue
BOD, carbonaceous [5 day, 20 C]
0% over limit
Discharged 0 kg/d against a permitted limit of 256.05599785 kg/d (7 DA AVG)
DMR, Limited - Overdue
Toxicity [acute], Pimephales promelas [Fathead Minnow]
0% over limit
Discharged 0 pass=0;fail=1 against a permitted limit of 1 pass=0;fail=1 (DAILY MX)
DMR, Limited - Overdue
Copper, total [as Cu]
0% over limit
Discharged 0 kg/d against a permitted limit of 0.1079158 kg/d (30DA AVG)
DMR, Limited - Overdue
Solids, total suspended
0% over limit
Discharged 0 kg/d against a permitted limit of 287.83599758 kg/d (7 DA AVG)
DMR, Limited - Overdue
Copper, total [as Cu]
0% over limit
Discharged 0 kg/d against a permitted limit of 0.1721114 kg/d (DAILY MX)
DMR, Limited - Overdue
Nitrogen, ammonia total [as N]
0% over limit
Discharged 0 mg/L against a permitted limit of 12.6 mg/L (DAILY MX)
DMR, Limited - Overdue
Chloride [as Cl]
0% over limit
Discharged 0 kg/d against a permitted limit of 2487.0119791 kg/d (30DA AVG)
DMR, Limited - Overdue
Nitrogen, ammonia total [as N]
0% over limit
Discharged 0 mg/L against a permitted limit of 1.6 mg/L (30DA AVG)
DMR, Limited - Overdue
Nitrogen, ammonia total [as N]
0% over limit
Discharged 0 kg/d against a permitted limit of 77.40699935 kg/d (DAILY MX)
DMR, Limited - Overdue
Copper, total [as Cu]
0% over limit
Discharged 0 mg/L against a permitted limit of 0.01687 mg/L (30DA AVG)
DMR, Limited - Overdue
pH
0% over limit
Discharged 0 SU against a permitted limit of 6.5 SU (DAILY MN)
DMR, Limited - Overdue
Chloride [as Cl]
0% over limit
Discharged 0 mg/L against a permitted limit of 629 mg/L (DAILY MX)
DMR, Limited - Overdue
pH
0% over limit
Discharged 0 SU against a permitted limit of 9 SU (DAILY MX)
DMR, Limited - Overdue
BOD, carbonaceous [5 day, 20 C]
0% over limit
Discharged 0 kg/d against a permitted limit of 159.80799866 kg/d (30DA AVG)
DMR, Limited - Overdue
Solids, total suspended
0% over limit
Discharged 0 mg/L against a permitted limit of 30 mg/L (30DA AVG)
DMR, Limited - Overdue
E. coli
0% over limit
Discharged 0 MPN/100mL against a permitted limit of 126 MPN/100mL (GEO MEAN)
DMR, Limited - Overdue
BOD, carbonaceous [5 day, 20 C]
0% over limit
Discharged 0 mg/L against a permitted limit of 25 mg/L (30DA AVG)
DMR, Limited - Overdue
Chloride [as Cl]
0% over limit
Discharged 0 mg/L against a permitted limit of 389 mg/L (30DA 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
Solids, total suspended
0% over limit
Discharged 0 mg/L against a permitted limit of 45 mg/L (7 DA AVG)
DMR, Limited - Overdue
Copper, total [as Cu]
0% over limit
Discharged 0 mg/L against a permitted limit of 0.0269 mg/L (DAILY MX)
DMR, Limited - Overdue
Chloride [as Cl]
0% over limit
Discharged 0 kg/d against a permitted limit of 4023.80196619 kg/d (DAILY MX)
DMR, Limited - Overdue
April 30, 2025
pH
0% over limit
Discharged 9.07 SU against a permitted limit of 9 SU (DAILY MX)
DMR, Limited - Numeric Violation
March 31, 2025
Copper, total [as Cu]
30% over limit
Discharged 0.022 mg/L against a permitted limit of 0.01687 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
Copper, total [as Cu]
19% over limit
Discharged 0.0321 mg/L against a permitted limit of 0.0269 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 9.4 SU against a permitted limit of 9 SU (DAILY MX)
DMR, Limited - Numeric Violation
February 28, 2025
Copper, total [as Cu]
5% over limit
Discharged 0.0177 mg/L against a permitted limit of 0.01687 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 9.32 SU against a permitted limit of 9 SU (DAILY MX)
DMR, Limited - Numeric Violation
January 31, 2025
pH
0% over limit
Discharged 10.01 SU against a permitted limit of 9 SU (DAILY MX)
DMR, Limited - Numeric Violation
December 31, 2024
pH
0% over limit
Discharged 9.82 SU against a permitted limit of 9 SU (DAILY MX)
DMR, Limited - Numeric Violation
November 30, 2024
pH
0% over limit
Discharged 9.63 SU against a permitted limit of 9 SU (DAILY MX)
DMR, Limited - Numeric Violation
October 31, 2024
Copper, total [as Cu]
13% over limit
Discharged 0.0304 mg/L against a permitted limit of 0.0269 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Copper, total [as Cu]
9% over limit
Discharged 0.01834 mg/L against a permitted limit of 0.01687 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 9.45 SU against a permitted limit of 9 SU (DAILY MX)
DMR, Limited - Numeric Violation
September 30, 2024
pH
0% over limit
Discharged 9.18 SU against a permitted limit of 9 SU (DAILY MX)
DMR, Limited - Numeric Violation
August 31, 2024
Copper, total [as Cu]
18% over limit
Discharged 0.0199 mg/L against a permitted limit of 0.01687 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
July 31, 2024
pH
0% over limit
Discharged 9.01 SU against a permitted limit of 9 SU (DAILY MX)
DMR, Limited - Numeric Violation
First flagged
April 14, 2026 (3 months ago)
Last confirmed
July 13, 2026 (24 days ago)