KAYENTA WASTEWATER TREATMENT LAGOON
NPDES ID: NN0020281
E — SNC: Effluent violation (monthly average limit)
The facility discharged more of a pollutant than its permit allows, based on a monthly average.
Violations
December 31, 2025
BOD, 5-day, 20 deg. C
82% over limit
Discharged 394.99361668 kg/d against a permitted limit of 216.55799818 kg/d (WKLY AVG)
DMR, Limited - Numeric Violation
E. coli
Limit violation
Discharged 2419.6 MPN/100mL against a permitted limit of 235 MPN/100mL (DAILY MX)
DMR, Limited - Numeric Violation
E. coli
997% over limit
Discharged 1381.98 MPN/100mL against a permitted limit of 126 MPN/100mL (GEO MEAN)
DMR, Limited - Numeric Violation
BOD, 5-day, 20 deg. C
50% over limit
Discharged 97.6 mg/L against a permitted limit of 65 mg/L (WKLY AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
1460% over limit
Discharged 15600000 mg/L against a permitted limit of 1000000 mg/L (MO AVG)
DMR, Limited - Numeric Violation
BOD, 5-day, percent removal
144% over limit
Discharged 14.6 % against a permitted limit of 65 % (MO AV MN)
DMR, Limited - Numeric Violation
BOD, 5-day, 20 deg. C
117% over limit
Discharged 97.6 mg/L against a permitted limit of 45 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Solids, suspended percent removal
186% over limit
Discharged 0 % against a permitted limit of 65 % (MO AV MN)
DMR, Limited - Numeric Violation
November 30, 2025
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR7d P promelas
0% over limit
Discharged 1 % against a permitted limit of 50 % (DAILY MX)
DMR, Limited - Overdue
Chronic Mthd Growth Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, Static96hr R subcapitata
0% over limit
Discharged 1 % against a permitted limit of 50 % (DAILY MX)
DMR, Limited - Overdue
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR8dmax C dubia
0% over limit
Discharged 1 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (DAILY MX)
DMR, Monitor Only - Overdue
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR7d P promelas
Limit violation
Discharged 1 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (MO MED)
DMR, Limited - Overdue
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR7d P promelas
Limit violation
Discharged 1 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (MO MED)
DMR, Limited - Numeric Violation
E. coli
930% over limit
Discharged 2419.6 MPN/100mL against a permitted limit of 235 MPN/100mL (DAILY MX)
DMR, Limited - Numeric Violation
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR8dmax C dubia
0% over limit
Discharged 1 % against a permitted limit of 50 % (DAILY MX)
DMR, Limited - Overdue
Chronic Mthd Growth Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, Static96hr R subcapitata
Limit violation
Discharged 1 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (MO MED)
DMR, Limited - Overdue
Chronic Mthd Growth Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, Static96hr R subcapitata
Limit violation
Discharged 1 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (MO MED)
DMR, Limited - Numeric Violation
BOD, 5-day, 20 deg. C
22% over limit
Discharged 79 mg/L against a permitted limit of 65 mg/L (WKLY AVG)
DMR, Limited - Numeric Violation
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR7d P promelas
0% over limit
Discharged 1 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (DAILY MX)
DMR, Monitor Only - Overdue
BOD, 5-day, 20 deg. C
76% over limit
Discharged 79 mg/L against a permitted limit of 45 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
2720% over limit
Discharged 28200000 mg/L against a permitted limit of 1000000 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR8dmax C dubia
Limit violation
Discharged 1 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (MO MED)
DMR, Limited - Overdue
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR8dmax C dubia
Limit violation
Discharged 1 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (MO MED)
DMR, Limited - Numeric Violation
Chronic Mthd Growth Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, Static96hr R subcapitata
0% over limit
Discharged 1 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (DAILY MX)
DMR, Monitor Only - Overdue
October 31, 2025
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR7d P promelas
0% over limit
Discharged 1 % against a permitted limit of 50 % (DAILY MX)
DMR, Limited - Overdue
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR8dmax C dubia
Limit violation
Discharged 1 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (MO MED)
DMR, Limited - Overdue
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR8dmax C dubia
Limit violation
Discharged 1 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (MO MED)
DMR, Limited - Numeric Violation
Chronic Mthd Growth Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, Static96hr R subcapitata
0% over limit
Discharged 0 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (DAILY MX)
DMR, Monitor Only - Overdue
BOD, 5-day, 20 deg. C
30% over limit
Discharged 84.4 mg/L against a permitted limit of 65 mg/L (WKLY AVG)
DMR, Limited - Numeric Violation
E. coli
Limit violation
Discharged 2419.6 MPN/100mL against a permitted limit of 235 MPN/100mL (DAILY MX)
DMR, Limited - Numeric Violation
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR7d P promelas
Limit violation
Discharged 1 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (MO MED)
DMR, Limited - Overdue
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR7d P promelas
Limit violation
Discharged 1 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (MO MED)
DMR, Limited - Numeric Violation
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR8dmax C dubia
0% over limit
Discharged 1 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (DAILY MX)
DMR, Monitor Only - Overdue
Chronic Mthd Growth Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, Static96hr R subcapitata
0% over limit
Discharged 0 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (MO MED)
DMR, Limited - Overdue
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR7d P promelas
0% over limit
Discharged 1 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (DAILY MX)
DMR, Monitor Only - Overdue
Nitrogen, ammonia total [as N]
1888% over limit
Discharged 19880000 mg/L against a permitted limit of 1000000 mg/L (MO AVG)
DMR, Limited - Numeric Violation
E. coli
698% over limit
Discharged 1005.21 MPN/100mL against a permitted limit of 126 MPN/100mL (GEO MEAN)
DMR, Limited - Numeric Violation
BOD, 5-day, 20 deg. C
88% over limit
Discharged 84.4 mg/L against a permitted limit of 45 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Chronic Mthd Growth Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, Static96hr R subcapitata
0% over limit
Discharged 0 % against a permitted limit of 50 % (DAILY MX)
DMR, Limited - Overdue
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR8dmax C dubia
0% over limit
Discharged 1 % against a permitted limit of 50 % (DAILY MX)
DMR, Limited - Overdue
September 30, 2025
E. coli
388% over limit
Discharged 614.747 MPN/100mL against a permitted limit of 126 MPN/100mL (GEO MEAN)
DMR, Limited - Numeric Violation
BOD, 5-day, 20 deg. C
33% over limit
Discharged 59.9 mg/L against a permitted limit of 45 mg/L (MO AVG)
DMR, Limited - Numeric Violation
BOD, 5-day, percent removal
0% over limit
Discharged 89.68 % against a permitted limit of 65 % (MO AV MN)
DMR, Limited - Overdue
BOD, 5-day, 20 deg. C
0% over limit
Discharged 45.53619962 kg/d against a permitted limit of 216.55799818 kg/d (WKLY AVG)
DMR, Limited - Overdue
Flow, in conduit or thru treatment plant
0% over limit
Discharged 0.128 MGD against a permitted limit of 0 MGD (MO AVG)
DMR, Monitor Only - Overdue
Flow, in conduit or thru treatment plant
0% over limit
Discharged 0.201 MGD against a permitted limit of 0 MGD (DAILY MX)
DMR, Monitor Only - Overdue
Solids, total suspended
0% over limit
Discharged 13.68355989 kg/d against a permitted limit of 449.91399622 kg/d (WKLY AVG)
DMR, Limited - Overdue
Flow, in conduit or thru treatment plant
0% over limit
Discharged 0.201 MGD against a permitted limit of 0 MGD (DAILY MX)
DMR, Monitor Only - Overdue
Solids, total suspended
0% over limit
Discharged 8.71225993 kg/d against a permitted limit of 300.09399748 kg/d (MO AVG)
DMR, Limited - Overdue
BOD, 5-day, 20 deg. C
0% over limit
Discharged 28.99697976 kg/d against a permitted limit of 148.91199875 kg/d (MO AVG)
DMR, Limited - Overdue
Flow, in conduit or thru treatment plant
0% over limit
Discharged 0.128 MGD against a permitted limit of 0 MGD (MO AVG)
DMR, Monitor Only - Overdue
E. coli
930% over limit
Discharged 2419.6 MPN/100mL against a permitted limit of 235 MPN/100mL (DAILY MX)
DMR, Limited - Numeric Violation
Solids, suspended percent removal
0% over limit
Discharged 96.92 % against a permitted limit of 65 % (MO AV MN)
DMR, Limited - Overdue
Nitrogen, ammonia total [as N]
1420% over limit
Discharged 15200000 mg/L against a permitted limit of 1000000 mg/L (MO AVG)
DMR, Limited - Overdue
Nitrogen, ammonia total [as N]
1420% over limit
Discharged 15200000 mg/L against a permitted limit of 1000000 mg/L (MO AVG)
DMR, Limited - Numeric Violation
August 31, 2025
Flow, in conduit or thru treatment plant
0% over limit
Discharged 0.212 MGD against a permitted limit of 0 MGD (DAILY MX)
DMR, Monitor Only - Overdue
Solids, total suspended
0% over limit
Discharged 18.99989984 kg/d against a permitted limit of 449.91399622 kg/d (WKLY AVG)
DMR, Limited - Overdue
Solids, total suspended
0% over limit
Discharged 12.0990999 kg/d against a permitted limit of 300.09399748 kg/d (MO AVG)
DMR, Limited - Overdue
Flow, in conduit or thru treatment plant
0% over limit
Discharged 0.212 MGD against a permitted limit of 0 MGD (DAILY MX)
DMR, Monitor Only - Overdue
BOD, 5-day, 20 deg. C
0% over limit
Discharged 50.59375957 kg/d against a permitted limit of 216.55799818 kg/d (WKLY AVG)
DMR, Limited - Overdue
Flow, in conduit or thru treatment plant
0% over limit
Discharged 0.135 MGD against a permitted limit of 0 MGD (MO AVG)
DMR, Monitor Only - Overdue
E. coli
Limit violation
Discharged 2419.6 MPN/100mL against a permitted limit of 235 MPN/100mL (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
650% over limit
Discharged 7500000 mg/L against a permitted limit of 1000000 mg/L (MO AVG)
DMR, Limited - Numeric Violation
BOD, 5-day, percent removal
0% over limit
Discharged 81.19 % against a permitted limit of 65 % (MO AV MN)
DMR, Limited - Overdue
BOD, 5-day, 20 deg. C
40% over limit
Discharged 63.1 mg/L against a permitted limit of 45 mg/L (MO AVG)
DMR, Limited - Numeric Violation
BOD, 5-day, 20 deg. C
0% over limit
Discharged 32.21583973 kg/d against a permitted limit of 148.91199875 kg/d (MO AVG)
DMR, Limited - Overdue
E. coli
159% over limit
Discharged 326.13 MPN/100mL against a permitted limit of 126 MPN/100mL (GEO MEAN)
DMR, Limited - Numeric Violation
Solids, suspended percent removal
0% over limit
Discharged 81.9 % against a permitted limit of 65 % (MO AV MN)
DMR, Limited - Overdue
Flow, in conduit or thru treatment plant
0% over limit
Discharged 0.135 MGD against a permitted limit of 0 MGD (MO AVG)
DMR, Monitor Only - Overdue
July 31, 2025
Nitrogen, ammonia total [as N]
614% over limit
Discharged 7140000 mg/L against a permitted limit of 1000000 mg/L (MO AVG)
DMR, Limited - Numeric Violation
BOD, 5-day, 20 deg. C
32% over limit
Discharged 59.6 mg/L against a permitted limit of 45 mg/L (MO AVG)
DMR, Limited - Numeric Violation
June 30, 2025
BOD, 5-day, 20 deg. C
5% over limit
Discharged 68.4 mg/L against a permitted limit of 65 mg/L (WKLY AVG)
DMR, Limited - Numeric Violation
BOD, 5-day, 20 deg. C
52% over limit
Discharged 68.4 mg/L against a permitted limit of 45 mg/L (MO AVG)
DMR, Limited - Numeric Violation
May 31, 2025
E. coli
31% over limit
Discharged 307.6 MPN/100mL against a permitted limit of 235 MPN/100mL (DAILY MX)
DMR, Limited - Numeric Violation
Solids, suspended percent removal
22% over limit
Discharged 57.2 % against a permitted limit of 65 % (MO AV MN)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
875% over limit
Discharged 9750000 mg/L against a permitted limit of 1000000 mg/L (MO AVG)
DMR, Limited - Numeric Violation
BOD, 5-day, 20 deg. C
0% over limit
Discharged 45.2 mg/L against a permitted limit of 45 mg/L (MO AVG)
DMR, Limited - Numeric Violation
April 30, 2025
Nitrogen, ammonia total [as N]
260% over limit
Discharged 3600000 mg/L against a permitted limit of 1000000 mg/L (MO AVG)
DMR, Limited - Numeric Violation
E. coli
561% over limit
Discharged 1553.1 MPN/100mL against a permitted limit of 235 MPN/100mL (DAILY MX)
DMR, Limited - Numeric Violation
February 28, 2025
Nitrogen, ammonia total [as N]
418% over limit
Discharged 5180000 mg/L against a permitted limit of 1000000 mg/L (MO AVG)
DMR, Limited - Numeric Violation
January 31, 2025
Nitrogen, ammonia total [as N]
655% over limit
Discharged 7550000 mg/L against a permitted limit of 1000000 mg/L (MO AVG)
DMR, Limited - Numeric Violation
December 31, 2024
Nitrogen, ammonia total [as N]
102% over limit
Discharged 2020000 mg/L against a permitted limit of 1000000 mg/L (MO AVG)
DMR, Limited - Numeric Violation
October 31, 2024
BOD, 5-day, 20 deg. C
41% over limit
Discharged 63.5 mg/L against a permitted limit of 45 mg/L (MO AVG)
DMR, Limited - Numeric Violation
September 30, 2024
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR8dmax C dubia
0% over limit
Discharged 0 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (MO MED)
DMR, Limited - Overdue
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR7d P promelas
0% over limit
Discharged 0 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (DAILY MX)
DMR, Monitor Only - Overdue
Chronic Mthd Growth Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, Static96hr R subcapitata
0% over limit
Discharged 0 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (MO MED)
DMR, Limited - Overdue
Chronic Mthd Growth Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, Static96hr R subcapitata
0% over limit
Discharged 0 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (DAILY MX)
DMR, Monitor Only - Overdue
pH
0% over limit
Discharged 9.42 SU against a permitted limit of 9 SU (MAXIMUM)
DMR, Limited - Numeric Violation
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR8dmax C dubia
0% over limit
Discharged 0 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (DAILY MX)
DMR, Monitor Only - Overdue
BOD, 5-day, 20 deg. C
21% over limit
Discharged 54.6 mg/L against a permitted limit of 45 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Chronic Mthd Growth Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, Static96hr R subcapitata
0% over limit
Discharged 0 % against a permitted limit of 50 % (DAILY MX)
DMR, Limited - Overdue
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR7d P promelas
0% over limit
Discharged 0 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (MO MED)
DMR, Limited - Overdue
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR7d P promelas
0% over limit
Discharged 0 % against a permitted limit of 50 % (DAILY MX)
DMR, Limited - Overdue
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR8dmax C dubia
0% over limit
Discharged 0 % against a permitted limit of 50 % (DAILY MX)
DMR, Limited - Overdue
August 31, 2024
Nitrogen, ammonia total [as N]
192% over limit
Discharged 2920000 mg/L against a permitted limit of 1000000 mg/L (MO AVG)
DMR, Limited - Numeric Violation
July 31, 2024
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR8dmax C dubia
0% over limit
Discharged 0 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (MO MED)
DMR, Limited - Overdue
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR7d P promelas
0% over limit
Discharged 0 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (DAILY MX)
DMR, Monitor Only - Overdue
Chronic Mthd Growth Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, Static96hr R subcapitata
0% over limit
Discharged 0 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (MO MED)
DMR, Limited - Overdue
pH
0% over limit
Discharged 9.15 SU against a permitted limit of 9 SU (MAXIMUM)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
423% over limit
Discharged 5230000 mg/L against a permitted limit of 1000000 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR7d P promelas
0% over limit
Discharged 0 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (MO MED)
DMR, Limited - Overdue
Chronic Mthd Growth Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, Static96hr R subcapitata
0% over limit
Discharged 0 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (DAILY MX)
DMR, Monitor Only - Overdue
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR7d P promelas
0% over limit
Discharged 0 % against a permitted limit of 50 % (DAILY MX)
DMR, Limited - Overdue
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR8dmax C dubia
0% over limit
Discharged 0 % against a permitted limit of 50 % (DAILY MX)
DMR, Limited - Overdue
Chronic Mthd Growth Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, Static96hr R subcapitata
0% over limit
Discharged 0 % against a permitted limit of 50 % (DAILY MX)
DMR, Limited - Overdue
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR8dmax C dubia
0% over limit
Discharged 0 pass=0;fail=1 against a permitted limit of 0 pass=0;fail=1 (DAILY MX)
DMR, Monitor Only - Overdue
First flagged
April 14, 2026 (3 months ago)
Last confirmed
July 13, 2026 (23 days ago)