MONARCH MINE DEWATERING SITE
NPDES ID: PA0255777
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: 18 effluent violations.
Violations
April 30, 2026
Iron, total [as Fe]
2293% over limit
Discharged 71.8 mg/L against a permitted limit of 3 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Aluminum, total [as Al]
4127% over limit
Discharged 31.7 mg/L against a permitted limit of 0.75 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Iron, total [as Fe]
4687% over limit
Discharged 71.8 mg/L against a permitted limit of 1.5 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Manganese, total [as Mn]
63% over limit
Discharged 1.63 mg/L against a permitted limit of 1 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Manganese, total [as Mn]
57% over limit
Discharged 3.13 mg/L against a permitted limit of 2 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Copper, total [as Cu]
122% over limit
Discharged 0.02 mg/L against a permitted limit of 0.009 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Selenium, total [as Se]
139% over limit
Discharged 0.0239 mg/L against a permitted limit of 0.01 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Aluminum, total [as Al]
7807% over limit
Discharged 59.3 mg/L against a permitted limit of 0.75 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Aluminum, total [as Al]
4127% over limit
Discharged 31.7 mg/L against a permitted limit of 0.75 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Selenium, total [as Se]
100% over limit
Discharged 0.01 mg/L against a permitted limit of 0.005 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Aluminum, total [as Al]
7807% over limit
Discharged 59.3 mg/L against a permitted limit of 0.75 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Aluminum, total [as Al]
72% over limit
Discharged 1.29 mg/L against a permitted limit of 0.75 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Iron, total [as Fe]
85% over limit
Discharged 2.77 mg/L against a permitted limit of 1.5 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Copper, total [as Cu]
60% over limit
Discharged 0.0288 mg/L against a permitted limit of 0.018 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Aluminum, total [as Al]
72% over limit
Discharged 1.29 mg/L against a permitted limit of 0.75 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Manganese, total [as Mn]
213% over limit
Discharged 3.13 mg/L against a permitted limit of 1 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Iron, total [as Fe]
1767% over limit
Discharged 56 mg/L against a permitted limit of 3 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Iron, total [as Fe]
3633% over limit
Discharged 56 mg/L against a permitted limit of 1.5 mg/L (MO AVG)
DMR, Limited - Numeric Violation
March 31, 2026
Aluminum, total [as Al]
12% over limit
Discharged 0.839 mg/L against a permitted limit of 0.75 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Aluminum, total [as Al]
12% over limit
Discharged 0.839 mg/L against a permitted limit of 0.75 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
February 28, 2026
Manganese, total [as Mn]
1043% over limit
Discharged 19 mg/L against a permitted limit of 1.663 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Manganese, total [as Mn]
480% over limit
Discharged 5.8 mg/L against a permitted limit of 1 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Osmotic pressure, total, unf whl wtr
46% over limit
Discharged 73 mOsm/kg against a permitted limit of 50 mOsm/kg (MO AVG)
DMR, Limited - Numeric Violation
Solids, total suspended
17% over limit
Discharged 82 mg/L against a permitted limit of 70 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
January 31, 2026
Manganese, total [as Mn]
982% over limit
Discharged 18 mg/L against a permitted limit of 1.663 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Manganese, total [as Mn]
520% over limit
Discharged 6.2 mg/L against a permitted limit of 1 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Solids, total suspended
334% over limit
Discharged 152 mg/L against a permitted limit of 35 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Solids, total suspended
523% over limit
Discharged 436 mg/L against a permitted limit of 70 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
December 31, 2025
Aluminum, total [as Al]
2020% over limit
Discharged 15.9 mg/L against a permitted limit of 0.75 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Iron, total [as Fe]
3893% over limit
Discharged 59.9 mg/L against a permitted limit of 1.5 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Aluminum, total [as Al]
2020% over limit
Discharged 15.9 mg/L against a permitted limit of 0.75 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Aluminum, total [as Al]
4900% over limit
Discharged 37.5 mg/L against a permitted limit of 0.75 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Manganese, total [as Mn]
150% over limit
Discharged 2.5 mg/L against a permitted limit of 1 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Manganese, total [as Mn]
25% over limit
Discharged 2.5 mg/L against a permitted limit of 2 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Aluminum, total [as Al]
4900% over limit
Discharged 37.5 mg/L against a permitted limit of 0.75 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Iron, total [as Fe]
493% over limit
Discharged 17.8 mg/L against a permitted limit of 3 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Iron, total [as Fe]
1897% over limit
Discharged 59.9 mg/L against a permitted limit of 3 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Iron, total [as Fe]
1087% over limit
Discharged 17.8 mg/L against a permitted limit of 1.5 mg/L (MO AVG)
DMR, Limited - Numeric Violation
November 30, 2025
Aluminum, total [as Al]
2647% over limit
Discharged 20.6 mg/L against a permitted limit of 0.75 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Aluminum, total [as Al]
2940% over limit
Discharged 22.8 mg/L against a permitted limit of 0.75 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Manganese, total [as Mn]
60% over limit
Discharged 1.6 mg/L against a permitted limit of 1 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Iron, total [as Fe]
1177% over limit
Discharged 38.3 mg/L against a permitted limit of 3 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Iron, total [as Fe]
2347% over limit
Discharged 36.7 mg/L against a permitted limit of 1.5 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Iron, total [as Fe]
2453% over limit
Discharged 38.3 mg/L against a permitted limit of 1.5 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Iron, total [as Fe]
1123% over limit
Discharged 36.7 mg/L against a permitted limit of 3 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Aluminum, total [as Al]
2940% over limit
Discharged 22.8 mg/L against a permitted limit of 0.75 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Aluminum, total [as Al]
2647% over limit
Discharged 20.6 mg/L against a permitted limit of 0.75 mg/L (MO AVG)
DMR, Limited - Numeric Violation
October 31, 2025
Cadmium, total [as Cd]
30% over limit
Discharged 0.00078 mg/L against a permitted limit of 0.0006 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Cadmium, total [as Cd]
100% over limit
Discharged 0.0006 mg/L against a permitted limit of 0.0003 mg/L (MO AVG)
DMR, Limited - Numeric Violation
September 30, 2025
Solids, total suspended
160% over limit
Discharged 182 mg/L against a permitted limit of 70 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Solids, total suspended
97% over limit
Discharged 69 mg/L against a permitted limit of 35 mg/L (MO AVG)
DMR, Limited - Numeric Violation
July 31, 2025
Osmotic pressure, total, unf whl wtr
8% over limit
Discharged 54 mOsm/kg against a permitted limit of 50 mOsm/kg (MO AVG)
DMR, Limited - Numeric Violation
May 31, 2025
Chromium, hexavalent [as Cr]
233% over limit
Discharged 0.02 mg/L against a permitted limit of 0.006 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Chromium, hexavalent [as Cr]
53% over limit
Discharged 0.0184 mg/L against a permitted limit of 0.012 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
March 31, 2025
Iron, total [as Fe]
237% over limit
Discharged 10.1 mg/L against a permitted limit of 3 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Aluminum, total [as Al]
433% over limit
Discharged 4 mg/L against a permitted limit of 0.75 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Iron, total [as Fe]
573% over limit
Discharged 10.1 mg/L against a permitted limit of 1.5 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Aluminum, total [as Al]
433% over limit
Discharged 4 mg/L against a permitted limit of 0.75 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
First flagged
April 14, 2026 (3 months ago)
Last confirmed
July 13, 2026 (23 days ago)