SILVER BELL TAILINGS
NPDES ID: CO0046931
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: 5 effluent violations.
Violations
May 31, 2026
Iron, total recoverable
557% over limit
Discharged 740.00003515 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 5.9 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
April 30, 2026
pH
0% over limit
Discharged 6.3 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6.4 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
Iron, total recoverable
364% over limit
Discharged 522.00002479 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
March 31, 2026
LC50 Static Renewal 48Hr Acute Ceriodaphnia dubia
93% over limit
Discharged 7 % against a permitted limit of 100 % (MN VALUE)
DMR, Limited - Numeric Violation
LC50 Static Renewal 96Hr Acute Pimephales promelas
94% over limit
Discharged 5.7 % against a permitted limit of 100 % (MN VALUE)
DMR, Limited - Numeric Violation
Iron, total recoverable
285% over limit
Discharged 433.00002057 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
LC50 Static Renewal 96Hr Acute Pimephales promelas
93% over limit
Discharged 7.49 % against a permitted limit of 100 % (MN VALUE)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6.2 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
LC50 Static Renewal 48Hr Acute Ceriodaphnia dubia
71% over limit
Discharged 29.16 % against a permitted limit of 100 % (MN VALUE)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6.2 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
February 28, 2026
pH
0% over limit
Discharged 6.2 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
Iron, total recoverable
62% over limit
Discharged 182.00000864 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
Iron, total recoverable
682% over limit
Discharged 880.0000418 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
January 31, 2026
Iron, total recoverable
723% over limit
Discharged 927.00004403 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6.3 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6.2 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
Iron, total recoverable
73% over limit
Discharged 195.00000926 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
December 31, 2025
LC50 Static Renewal 96Hr Acute Pimephales promelas
90% over limit
Discharged 10 % against a permitted limit of 100 % (MN VALUE)
DMR, Limited - Numeric Violation
LC50 Static Renewal 48Hr Acute Ceriodaphnia dubia
93% over limit
Discharged 7.07 % against a permitted limit of 100 % (MN VALUE)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 5.8 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6.1 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
Iron, total recoverable
678% over limit
Discharged 876.00004161 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
November 30, 2025
Iron, total recoverable
590% over limit
Discharged 777.00003691 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6.3 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
October 31, 2025
pH
0% over limit
Discharged 6.4 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
Iron, total recoverable
393% over limit
Discharged 555.00002636 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
September 30, 2025
pH
0% over limit
Discharged 6.3 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
Iron, total recoverable
574% over limit
Discharged 759.00003605 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
LC50 Static Renewal 48Hr Acute Ceriodaphnia dubia
92% over limit
Discharged 8.12 % against a permitted limit of 100 % (MN VALUE)
DMR, Limited - Numeric Violation
LC50 Static Renewal 96Hr Acute Pimephales promelas
90% over limit
Discharged 10.35 % against a permitted limit of 100 % (MN VALUE)
DMR, Limited - Numeric Violation
August 31, 2025
Iron, total recoverable
538% over limit
Discharged 718.0000341 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6.1 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
July 31, 2025
pH
0% over limit
Discharged 6.4 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6.2 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
Iron, total recoverable
471% over limit
Discharged 643.00003054 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
June 30, 2025
LC50 Static Renewal 96Hr Acute Pimephales promelas
42% over limit
Discharged 58.26 % against a permitted limit of 100 % (MN VALUE)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6.4 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
LC50 Static Renewal 48Hr Acute Ceriodaphnia dubia
24% over limit
Discharged 75.9 % against a permitted limit of 100 % (MN VALUE)
DMR, Limited - Numeric Violation
LC50 Static Renewal 48Hr Acute Ceriodaphnia dubia
88% over limit
Discharged 12.31 % against a permitted limit of 100 % (MN VALUE)
DMR, Limited - Numeric Violation
LC50 Static Renewal 96Hr Acute Pimephales promelas
88% over limit
Discharged 11.89 % against a permitted limit of 100 % (MN VALUE)
DMR, Limited - Numeric Violation
Iron, total recoverable
265% over limit
Discharged 411.00001952 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6.4 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
May 31, 2025
Iron, total recoverable
380% over limit
Discharged 541.0000257 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6.4 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
April 30, 2025
Iron, total recoverable
325% over limit
Discharged 478.0000227 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6.2 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6.2 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
March 31, 2025
Iron, total recoverable
39% over limit
Discharged 157.00000746 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
LC50 Static Renewal 96Hr Acute Pimephales promelas
61% over limit
Discharged 39.33 % against a permitted limit of 100 % (MN VALUE)
DMR, Limited - Numeric Violation
LC50 Static Renewal 96Hr Acute Pimephales promelas
92% over limit
Discharged 7.58 % against a permitted limit of 100 % (MN VALUE)
DMR, Limited - Numeric Violation
Iron, total recoverable
586% over limit
Discharged 772.00003667 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
LC50 Static Renewal 48Hr Acute Ceriodaphnia dubia
78% over limit
Discharged 22.38 % against a permitted limit of 100 % (MN VALUE)
DMR, Limited - Numeric Violation
LC50 Static Renewal 48Hr Acute Ceriodaphnia dubia
94% over limit
Discharged 6.48 % against a permitted limit of 100 % (MN VALUE)
DMR, Limited - Numeric Violation
February 28, 2025
pH
0% over limit
Discharged 6.4 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
Iron, total recoverable
597% over limit
Discharged 785.00003729 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
January 31, 2025
Iron, total recoverable
617% over limit
Discharged 807.00003833 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6.4 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
December 31, 2024
LC50 Static Renewal 48Hr Acute Ceriodaphnia dubia
59% over limit
Discharged 41.4 % against a permitted limit of 100 % (MN VALUE)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6.3 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
LC50 Static Renewal 96Hr Acute Pimephales promelas
93% over limit
Discharged 7.07 % against a permitted limit of 100 % (MN VALUE)
DMR, Limited - Numeric Violation
LC50 Static Renewal 48Hr Acute Ceriodaphnia dubia
96% over limit
Discharged 3.54 % against a permitted limit of 100 % (MN VALUE)
DMR, Limited - Numeric Violation
Iron, total recoverable
576% over limit
Discharged 761.00003615 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
November 30, 2024
pH
0% over limit
Discharged 6.3 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
Iron, total recoverable
396% over limit
Discharged 558.0000265 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
Iron, total recoverable
183% over limit
Discharged 319.00001515 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6.4 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
October 31, 2024
Iron, total recoverable
533% over limit
Discharged 713.00003387 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6.3 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6.3 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
September 30, 2024
pH
0% over limit
Discharged 6.2 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
Iron, total recoverable
485% over limit
Discharged 659.0000313 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
LC50 Static Renewal 96Hr Acute Pimephales promelas
92% over limit
Discharged 7.81 % against a permitted limit of 100 % (MN VALUE)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6.4 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
LC50 Static Renewal 48Hr Acute Ceriodaphnia dubia
93% over limit
Discharged 7.07 % against a permitted limit of 100 % (MN VALUE)
DMR, Limited - Numeric Violation
August 31, 2024
Iron, total recoverable
504% over limit
Discharged 680.0000323 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6.3 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6.4 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
July 31, 2024
pH
0% over limit
Discharged 6.1 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
pH
0% over limit
Discharged 6.1 SU against a permitted limit of 6.5 SU (MINIMUM)
DMR, Limited - Numeric Violation
Iron, total recoverable
285% over limit
Discharged 433.00002057 mg/L against a permitted limit of 112.60000535 mg/L (30DA AVG)
DMR, Limited - Numeric Violation
First flagged
April 14, 2026 (3 months ago)
Last confirmed
July 13, 2026 (23 days ago)