Clean Water Act discharge permit · NPDES NN0021555

WINDOW ROCK WWTF, Fort Defiance, AZ: NPDES NN0021555 discharge permit, effluent exceedances, inspections, penalties

Administratively continuedPermit status
MajorDischarger class
139Pollutants under a numeric limit
9Pollutants with an effluent exceedance
0Inspections on file
0Formal enforcement actions

WINDOW ROCK WWTF, held by NAVAJO TRIBAL UTILITY AUTHORITY, holds NPDES permit NN0021555, which discharges to Black Creek. EPA’s file records it issued January 21, 2016 and expiring January 31, 2021.

WINDOW ROCK WWTF, Fort Defiance, Arizona: Individual permit NN0021555, held by NAVAJO TRIBAL UTILITY AUTHORITY; Publicly owned treatment works; Administratively continued (past its expiration date and still in force until reissued); issued January 21, 2016, term to January 31, 2021; discharges to BLACK CREEK.

BOD, 5-day, 20 deg. C: 10 limits, 263 violations of any kind, 207 effluent exceedances, latest April 30, 2020, largest 2,020% over the limit.
E. coli, colony forming units [CFU]: 4 limits, 94 violations of any kind, 86 effluent exceedances, latest May 31, 2026, largest 99,999% over the limit.
BOD, 5-day, percent removal: 2 limits, 88 violations of any kind, 51 effluent exceedances, latest April 30, 2020, largest 509% over the limit.
Solids, total suspended: 10 limits, 87 violations of any kind, 28 effluent exceedances, latest March 31, 2021, largest 610% over the limit.
Chlorine, total residual: 2 limits, 62 violations of any kind, 26 effluent exceedances, latest November 30, 2013, largest 9,066% over the limit.
Solids, suspended percent removal: 2 limits, 58 violations of any kind, 25 effluent exceedances, latest December 31, 2022, largest 554% over the limit.
Coliform, fecal general: 0 limits, 95 violations of any kind, 14 effluent exceedances, latest October 31, 2003, largest 5,900% over the limit.
pH: 4 limits, 76 violations of any kind, 6 effluent exceedances, latest March 31, 2022.
Nitrogen, ammonia total [as N]: 6 limits, 13 violations of any kind, 4 effluent exceedances, latest June 30, 2016, largest 2,148% over the limit.
Flow, in conduit or thru treatment plant: 8 limits, 82 violations of any kind, 0 effluent exceedances.
Pass/Fail Static Renewal 7Day Chronic Pimephales promelas: 8 limits, 54 violations of any kind, 0 effluent exceedances.
Solids, total dissolved: 6 limits, 25 violations of any kind, 0 effluent exceedances.
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR7d P promelas: 0 limits, 20 violations of any kind, 0 effluent exceedances.
Ammonia, unionized: 0 limits, 8 violations of any kind, 0 effluent exceedances.
Temperature, water deg. centigrade: 4 limits, 6 violations of any kind, 0 effluent exceedances.
Temperature, water deg. fahrenheit: 0 limits, 6 violations of any kind, 0 effluent exceedances.
Arsenic, total recoverable: 1 limit, 5 violations of any kind, 0 effluent exceedances.
Thallium, total recoverable: 1 limit, 5 violations of any kind, 0 effluent exceedances.
Copper, total recoverable: 1 limit, 5 violations of any kind, 0 effluent exceedances.
Heptachlor: 1 limit, 5 violations of any kind, 0 effluent exceedances.
Mercury, total recoverable: 1 limit, 5 violations of any kind, 0 effluent exceedances.
Hardness, total [as CaCO3]: 0 limits, 3 violations of any kind, 0 effluent exceedances.
Cyanide, total [as CN]: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Asbestos: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Selenium, total recoverable: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Beryllium, total recoverable [as Be]: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Chromium, hexavalent [as Cr]: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Chromium, trivalent [as Cr]: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Nickel, total recoverable: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Silver total recoverable: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Zinc, total recoverable: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Cadmium, total recoverable: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Lead, total recoverable: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Antimony, total recoverable: 1 limit, 2 violations of any kind, 0 effluent exceedances.
2-Methyl-4,6-dinitrophenol: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Dichlorobromomethane: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Carbon tetrachloride: 1 limit, 2 violations of any kind, 0 effluent exceedances.
1,2-Dichloroethane: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Bromoform: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Dibromochloromethane: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Chloroform: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Toluene: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Benzene: 1 limit, 2 violations of any kind, 0 effluent exceedances.
.delta.-BHC: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Acenaphthylene: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Acenaphthene: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Acrolein: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Acrylonitrile: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Anthracene: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Benzo[b]fluoranthene: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Benzo[k]fluoranthene: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Benzo[a]pyrene: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Bis[2-chloroethyl] ether: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Bis[2-chloroethoxy]methane: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Bis[2-chloroisopropyl] ether: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Butyl benzyl phthalate: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Chlorobenzene: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Chrysene: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Diethyl phthalate: 1 limit, 2 violations of any kind, 0 effluent exceedances.
Dimethyl phthalate: 1 limit, 2 violations of any kind, 0 effluent exceedances.

October 19, 2026: Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment (EP6).
August 31, 2026: Dry-weather unanticipated prohibited bypass discharge to waters of the U.S. - endangerment (EP6).
August 19, 2026: Wet-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment (EP6).
August 17, 2026: PR: Failure to submit noncompliance report - CSO, SSO, or Bypass [40 CFR 122.41(l)(6) & (m)(3)(ii)] (EP6).
August 11, 2026: Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment (EP6).
August 10, 2026: Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment (EP6).
July 23, 2026: Wet-weather unanticipated prohibited bypass discharge to waters of the U.S. - endangerment (EP6).
May 28, 2026: PR: Failure to submit noncompliance report - CSO, SSO, or Bypass [40 CFR 122.41(l)(6) & (m)(3)(ii)] (EP6).
May 22, 2026: Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment (EP6).
April 21, 2026: Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment (EP6).
March 6, 2026: Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment (EP6).
September 28, 2025: Wet-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment (EP6).
August 26, 2025: Wet-weather unanticipated prohibited bypass discharge to waters of the U.S. - endangerment (EP6).
August 25, 2025: Wet-weather unanticipated prohibited bypass discharge to waters of the U.S. - endangerment (EP6).
June 9, 2025: Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment (EP6).
February 16, 2025: Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment (EP6).
January 19, 2025: Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment (EP6).
January 3, 2025: Failure to submit report to the permitting authority of any anticipated bypass [122.41(m)(3)(i)] (EP6).
January 1, 2025: Wet-weather unanticipated prohibited bypass discharge to waters of the U.S. - endangerment (EP6).
August 11, 2024: Wet-weather unanticipated prohibited bypass discharge to waters of the U.S. - endangerment (EP6).
August 8, 2024: Wet-weather unanticipated prohibited bypass discharge to waters of the U.S. - endangerment (EP6).
August 4, 2024: PR: Failure to submit noncompliance report - CSO, SSO, or Bypass [40 CFR 122.41(l)(6) & (m)(3)(ii)] (EP6).
July 30, 2024: Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment (EP6).
July 29, 2024: Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment (EP6).
June 14, 2024: Failure to submit report to the permitting authority of any anticipated bypass [122.41(m)(3)(i)] (EP6).
May 14, 2024: Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment (EP6).
May 7, 2024: Dry-weather SSO, no discharge to waters of the U.S., not permit compliant, no endangerment (EP6).

Arizona holds 91 Publicly owned treatment works coverages of this permit type in EPA’s file; 17 were issued before NN0021555. NAVAJO TRIBAL UTILITY AUTHORITY holds 8 permits in Arizona.

Other permits held by NAVAJO TRIBAL UTILITY AUTHORITY

CHINLE WWTF, Chinle: NN0020265, issued July 10, 2018
KAYENTA WASTEWATER TREATMENT LAGOON, Kayenta: NN0020281, issued June 12, 2018
TUBA CITY WWTF, Tuba City: NN0020290, issued May 23, 2016
GANADO WWTP, Ganado: NN0022195, issued December 8, 2015
PINON WWTF, Pinon: NN0024228, issued August 16, 2011
KAYENTA WASTEWATER TREATMENT LAGOON, Kayenta: NNL020281, issued December 6, 2024
GANADO WWTP, Ganado: NNL022195, issued January 30, 2024

Coverages issued nearest NN0021555

July 26, 2013: ARIZONA CITY SANITARY DISTRICT - WWTP, Arizona City, AZ0024244, held by Arizona City Sanitary District
September 13, 2013: ORACLE SANITARY DISTRICT WWTP, Oracle, AZ0020681, held by Oracle Sanitary District
January 8, 2015: CITY OF WILLCOX - WWTP, Willcox, AZ0025771, held by City Of Willcox
February 5, 2015: JOINT VENTURE WWTF, Parker, AZ0021415, held by COLORADO RIVER SEWAGE SYSTEM
December 8, 2015: GANADO WWTP, Ganado, NN0022195, held by NAVAJO TRIBAL UTILITY AUTHORITY
May 23, 2016: TUBA CITY WWTF, Tuba City, NN0020290, held by NAVAJO TRIBAL UTILITY AUTHORITY
May 27, 2016: HON-DAH REGIONAL WWTF, Whiteriver, AZ0024589, held by WHITE MOUNTAIN APACHE TRIBE
June 27, 2016: USDOI BR - YUMA DESALTING PLANT, Yuma, AZ0025348, held by Us Bureau Of Reclamation
July 11, 2016: TOWN OF KEARNY WASTEWATER RECLAMATION FACILITY, Kearny, AZ0024449, held by Town Of Kearny
July 12, 2016: PIMA COUNTY - WWMD - MOUNT LEMMON WWTP, Mount Lemmon, AZ0022250, held by Pima County Regional Wastewater Reclamation Department

WINDOW ROCK WWTF among its neighbors

EPA’s permit file holds 1 discharge permits in the White Water Wash-Chinle Wash subwatershed (HUC 140802041104), NN0021555 among them. Its county holds 20, 1 of them major permits; NN0021555 is a major permit.

Identity

Facility as filed	WINDOW ROCK WWTF
Permittee as filed	NAVAJO TRIBAL UTILITY AUTHORITY
NPDES ID	NN0021555
Permit status	Administratively continued (past its expiration date and still in force until reissued)
Permit type	Individual permit
Discharger class	Major discharger
Facility type	Publicly owned treatment works
Program	Publicly owned treatment works
Issued	January 21, 2016
Expiration date	January 31, 2021
Address	Fort Defiance, AZ 86515
Receiving water	BLACK CREEK
Subwatershed	White Water Wash-Chinle Wash (HUC 140802041104)

Effluent limits and exceedances

144Pollutants on file
139Under a numeric limit
144With a violation of any kind
9With an effluent exceedance

An effluent exceedance is a discharge monitoring report value over the permit’s numeric limit (EPA’s violation code E90). A violation of any kind also counts a report not filed. Each row is EPA’s own count for that pollutant; the 60 with the most exceedances of 144 are shown.

Pollutant or measure	Limits	Violations, any kind	Effluent exceedances	Latest exceedance	Largest exceedance, as filed
BOD, 5-day, 20 deg. C	10	263	207	April 30, 2020	2,020% over the limit
E. coli, colony forming units [CFU]	4	94	86	May 31, 2026	99,999% over the limit
BOD, 5-day, percent removal	2	88	51	April 30, 2020	509% over the limit
Solids, total suspended	10	87	28	March 31, 2021	610% over the limit
Chlorine, total residual	2	62	26	November 30, 2013	9,066% over the limit
Solids, suspended percent removal	2	58	25	December 31, 2022	554% over the limit
Coliform, fecal general	0	95	14	October 31, 2003	5,900% over the limit
pH	4	76	6	March 31, 2022
Nitrogen, ammonia total [as N]	6	13	4	June 30, 2016	2,148% over the limit
Flow, in conduit or thru treatment plant	8	82	0
Pass/Fail Static Renewal 7Day Chronic Pimephales promelas	8	54	0
Solids, total dissolved	6	25	0
Chronic Mthd Sublethal Endpt, %Effect, Median TSTcHo R/nR Pass/Fail, StatR7d P promelas	0	20	0
Ammonia, unionized	0	8	0
Temperature, water deg. centigrade	4	6	0
Temperature, water deg. fahrenheit	0	6	0
Arsenic, total recoverable	1	5	0
Thallium, total recoverable	1	5	0
Copper, total recoverable	1	5	0
Heptachlor	1	5	0
Mercury, total recoverable	1	5	0
Hardness, total [as CaCO3]	0	3	0
Cyanide, total [as CN]	1	2	0
Asbestos	1	2	0
Selenium, total recoverable	1	2	0
Beryllium, total recoverable [as Be]	1	2	0
Chromium, hexavalent [as Cr]	1	2	0
Chromium, trivalent [as Cr]	1	2	0
Nickel, total recoverable	1	2	0
Silver total recoverable	1	2	0
Zinc, total recoverable	1	2	0
Cadmium, total recoverable	1	2	0
Lead, total recoverable	1	2	0
Antimony, total recoverable	1	2	0
2-Methyl-4,6-dinitrophenol	1	2	0
Dichlorobromomethane	1	2	0
Carbon tetrachloride	1	2	0
1,2-Dichloroethane	1	2	0
Bromoform	1	2	0
Dibromochloromethane	1	2	0
Chloroform	1	2	0
Toluene	1	2	0
Benzene	1	2	0
.delta.-BHC	1	2	0
Acenaphthylene	1	2	0
Acenaphthene	1	2	0
Acrolein	1	2	0
Acrylonitrile	1	2	0
Anthracene	1	2	0
Benzo[b]fluoranthene	1	2	0
Benzo[k]fluoranthene	1	2	0
Benzo[a]pyrene	1	2	0
Bis[2-chloroethyl] ether	1	2	0
Bis[2-chloroethoxy]methane	1	2	0
Bis[2-chloroisopropyl] ether	1	2	0
Butyl benzyl phthalate	1	2	0
Chlorobenzene	1	2	0
Chrysene	1	2	0
Diethyl phthalate	1	2	0
Dimethyl phthalate	1	2	0

Inspections, violations and enforcement

27Single-event violations

Date	What EPA recorded	Agency
October 19, 2026	Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment	EP6
August 31, 2026	Dry-weather unanticipated prohibited bypass discharge to waters of the U.S. - endangerment	EP6
August 19, 2026	Wet-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment	EP6
August 17, 2026	PR: Failure to submit noncompliance report - CSO, SSO, or Bypass [40 CFR 122.41(l)(6) & (m)(3)(ii)]	EP6
August 11, 2026	Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment	EP6
August 10, 2026	Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment	EP6
July 23, 2026	Wet-weather unanticipated prohibited bypass discharge to waters of the U.S. - endangerment	EP6
May 28, 2026	PR: Failure to submit noncompliance report - CSO, SSO, or Bypass [40 CFR 122.41(l)(6) & (m)(3)(ii)]	EP6
May 22, 2026	Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment	EP6
April 21, 2026	Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment	EP6
March 6, 2026	Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment	EP6
September 28, 2025	Wet-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment	EP6
August 26, 2025	Wet-weather unanticipated prohibited bypass discharge to waters of the U.S. - endangerment	EP6
August 25, 2025	Wet-weather unanticipated prohibited bypass discharge to waters of the U.S. - endangerment	EP6
June 9, 2025	Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment	EP6
February 16, 2025	Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment	EP6
January 19, 2025	Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment	EP6
January 3, 2025	Failure to submit report to the permitting authority of any anticipated bypass [122.41(m)(3)(i)]	EP6
January 1, 2025	Wet-weather unanticipated prohibited bypass discharge to waters of the U.S. - endangerment	EP6
August 11, 2024	Wet-weather unanticipated prohibited bypass discharge to waters of the U.S. - endangerment	EP6
August 8, 2024	Wet-weather unanticipated prohibited bypass discharge to waters of the U.S. - endangerment	EP6
August 4, 2024	PR: Failure to submit noncompliance report - CSO, SSO, or Bypass [40 CFR 122.41(l)(6) & (m)(3)(ii)]	EP6
July 30, 2024	Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment	EP6
July 29, 2024	Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment	EP6
June 14, 2024	Failure to submit report to the permitting authority of any anticipated bypass [122.41(m)(3)(i)]	EP6
May 14, 2024	Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment	EP6
May 7, 2024	Dry-weather SSO, no discharge to waters of the U.S., not permit compliant, no endangerment	EP6

Inspections

EPA’s inspection file holds no inspection for NPDES NN0021555.

Formal enforcement and penalties

0 formal actions, 0 of them with a penalty assessed. Federal and state penalties are separate figures from separate authorities and are shown as each was filed, never added together.

Informal enforcement

EPA’s informal enforcement file holds no action for NPDES NN0021555.

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Figures from EPA’s ICIS-NPDES download, loaded September 15, 2026.

This public-records page covers the NPDES discharge permit NN0021555 for the WINDOW ROCK WWTF in Fort Defiance, AZ, held by NAVAJO TRIBAL UTILITY AUTHORITY and discharging to Black Creek within the White Water Wash-Chinle Wash subwatershed (HUC 140802041104). The page lists a permit status of administratively continued, a discharger class of Major Discharger, and 144 pollutants on file, of which 139 are under a numeric limit and 144 show a violation. It also shows 9 pollutants with an effluent exceedance.