OGALLALA WASTEWATER TREATMENT FACILITY
NPDES ID: NE0040045
E — SNC: Effluent violation (monthly average limit)
The facility discharged more of a pollutant than its permit allows, based on a monthly average.
Violations
March 31, 2026
Nitrogen, ammonia total [as N]
279% over limit
Discharged 24.66 mg/L against a permitted limit of 6.5 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
313% over limit
Discharged 50.89 kg/d against a permitted limit of 12.31 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Oil and grease, hexane extr method
24% over limit
Discharged 12.4 mg/L against a permitted limit of 10 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
122% over limit
Discharged 28.9 mg/L against a permitted limit of 13.04 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
141% over limit
Discharged 59.64 kg/d against a permitted limit of 24.7 kg/d (DAILY MX)
DMR, Limited - Numeric Violation
Solids, total suspended
38% over limit
Discharged 41.5 mg/L against a permitted limit of 30 mg/L (MO AVG)
DMR, Limited - Numeric Violation
February 28, 2026
Nitrogen, ammonia total [as N]
51% over limit
Discharged 9.51 kg/d against a permitted limit of 6.29 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
26% over limit
Discharged 20.24 kg/d against a permitted limit of 16.02 kg/d (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
6% over limit
Discharged 4.84 mg/L against a permitted limit of 4.56 mg/L (MO AVG)
DMR, Limited - Numeric Violation
January 31, 2026
Nitrogen, ammonia total [as N]
99% over limit
Discharged 12.49 kg/d against a permitted limit of 6.29 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
32% over limit
Discharged 6.04 mg/L against a permitted limit of 4.56 mg/L (MO AVG)
DMR, Limited - Numeric Violation
December 31, 2025
Nitrogen, ammonia total [as N]
182% over limit
Discharged 32.7 mg/L against a permitted limit of 11.59 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
276% over limit
Discharged 23.65 kg/d against a permitted limit of 6.29 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
160% over limit
Discharged 11.85 mg/L against a permitted limit of 4.56 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
307% over limit
Discharged 65.27 kg/d against a permitted limit of 16.02 kg/d (DAILY MX)
DMR, Limited - Numeric Violation
Zinc, dissolved [as Zn]
0% over limit
Discharged 0 mg/L against a permitted limit of 0.553 mg/L (DAILY MX)
DMR, Limited - Overdue
Zinc, dissolved [as Zn]
0% over limit
Discharged 0 mg/L against a permitted limit of 0.276 mg/L (MO AVG)
DMR, Limited - Overdue
November 30, 2025
Nitrogen, ammonia total [as N]
50% over limit
Discharged 6.84 mg/L against a permitted limit of 4.56 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
24% over limit
Discharged 19.89 kg/d against a permitted limit of 16.02 kg/d (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
112% over limit
Discharged 13.34 kg/d against a permitted limit of 6.29 kg/d (MO AVG)
DMR, Limited - Numeric Violation
October 31, 2025
Nitrogen, ammonia total [as N]
380% over limit
Discharged 5.04 kg/d against a permitted limit of 1.05 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
787% over limit
Discharged 18.71 kg/d against a permitted limit of 2.11 kg/d (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
1276% over limit
Discharged 15 mg/L against a permitted limit of 1.09 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
648% over limit
Discharged 4.04 mg/L against a permitted limit of 0.54 mg/L (MO AVG)
DMR, Limited - Numeric Violation
September 30, 2025
Chromium, dissolved [as Cr]
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]
620% over limit
Discharged 7.56 kg/d against a permitted limit of 1.05 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
532% over limit
Discharged 3.413 mg/L against a permitted limit of 0.54 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Copper, dissolved [as Cu]
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]
313% over limit
Discharged 4.5 mg/L against a permitted limit of 1.09 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Mercury, total [as Hg]
0% over limit
Discharged 0 mg/L against a permitted limit of 0 mg/L (MO AVG)
DMR, Monitor Only - Overdue
Chromium, dissolved [as Cr]
0% over limit
Discharged 0 mg/L against a permitted limit of 0 mg/L (DAILY MX)
DMR, Monitor Only - Overdue
Copper, dissolved [as Cu]
0% over limit
Discharged 0 mg/L against a permitted limit of 0 mg/L (DAILY MX)
DMR, Monitor Only - Overdue
Mercury, total [as Hg]
0% over limit
Discharged 0 mg/L against a permitted limit of 0 mg/L (DAILY MX)
DMR, Monitor Only - Overdue
Toxicity [acute], Ceriodaphnia dubia
0% over limit
Discharged 0 toxic against a permitted limit of 1 toxic (VALUE)
DMR, Limited - Overdue
Nickel, dissolved [as Ni]
0% over limit
Discharged 0 mg/L against a permitted limit of 0 mg/L (DAILY MX)
DMR, Monitor Only - Overdue
Nitrogen, ammonia total [as N]
373% over limit
Discharged 9.97 kg/d against a permitted limit of 2.11 kg/d (DAILY MX)
DMR, Limited - Numeric Violation
Toxicity [acute], Pimephales promelas [Fathead Minnow]
0% over limit
Discharged 0 toxic against a permitted limit of 1 toxic (VALUE)
DMR, Limited - Overdue
Nickel, dissolved [as Ni]
0% over limit
Discharged 0 mg/L against a permitted limit of 0 mg/L (MO AVG)
DMR, Monitor Only - Overdue
August 31, 2025
Nitrogen, ammonia total [as N]
2377% over limit
Discharged 27 mg/L against a permitted limit of 1.09 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
2189% over limit
Discharged 12.36 mg/L against a permitted limit of 0.54 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
2821% over limit
Discharged 61.64 kg/d against a permitted limit of 2.11 kg/d (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
2587% over limit
Discharged 28.21 kg/d against a permitted limit of 1.05 kg/d (MO AVG)
DMR, Limited - Numeric Violation
July 31, 2025
Nitrogen, ammonia total [as N]
2523% over limit
Discharged 55.34 kg/d against a permitted limit of 2.11 kg/d (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
1001% over limit
Discharged 11.56 kg/d against a permitted limit of 1.05 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
2184% over limit
Discharged 24.9 mg/L against a permitted limit of 1.09 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
863% over limit
Discharged 5.2 mg/L against a permitted limit of 0.54 mg/L (MO AVG)
DMR, Limited - Numeric Violation
June 30, 2025
Zinc, dissolved [as Zn]
0% over limit
Discharged 0 mg/L against a permitted limit of 0.514 mg/L (DAILY MX)
DMR, Limited - Overdue
Zinc, dissolved [as Zn]
0% over limit
Discharged 0 mg/L against a permitted limit of 0.256 mg/L (MO AVG)
DMR, Limited - Overdue
March 31, 2025
Nitrogen, ammonia total [as N]
52% over limit
Discharged 18.72 kg/d against a permitted limit of 12.31 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
211% over limit
Discharged 40.5 mg/L against a permitted limit of 13.04 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
59% over limit
Discharged 10.34 mg/L against a permitted limit of 6.5 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
197% over limit
Discharged 73.33 kg/d against a permitted limit of 24.7 kg/d (DAILY MX)
DMR, Limited - Numeric Violation
February 28, 2025
Nitrogen, ammonia total [as N]
177% over limit
Discharged 44.43 kg/d against a permitted limit of 16.02 kg/d (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
98% over limit
Discharged 23 mg/L against a permitted limit of 11.59 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
116% over limit
Discharged 13.6 kg/d against a permitted limit of 6.29 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
54% over limit
Discharged 7.03 mg/L against a permitted limit of 4.56 mg/L (MO AVG)
DMR, Limited - Numeric Violation
September 30, 2024
Zinc, dissolved [as Zn]
0% over limit
Discharged 0 mg/L against a permitted limit of 0 mg/L (MO AVG)
DMR, Monitor Only - Overdue
Zinc, dissolved [as Zn]
0% over limit
Discharged 0 mg/L against a permitted limit of 0 mg/L (DAILY MX)
DMR, Monitor Only - Overdue
August 31, 2024
Nitrogen, ammonia total [as N]
566% over limit
Discharged 14.05 kg/d against a permitted limit of 2.11 kg/d (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
244% over limit
Discharged 3.61 kg/d against a permitted limit of 1.05 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
736% over limit
Discharged 9.11 mg/L against a permitted limit of 1.09 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
333% over limit
Discharged 2.34 mg/L against a permitted limit of 0.54 mg/L (MO AVG)
DMR, Limited - Numeric Violation
July 31, 2024
E. coli, MTEC-MF
46% over limit
Discharged 436 MPN/100mL against a permitted limit of 298 MPN/100mL (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
26% over limit
Discharged 1.37 mg/L against a permitted limit of 1.09 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
E. coli, MTEC-MF
98% over limit
Discharged 249.8 MPN/100mL against a permitted limit of 126 MPN/100mL (MO AVG)
DMR, Limited - Numeric Violation
First flagged
April 14, 2026 (3 months ago)
Last confirmed
July 13, 2026 (23 days ago)