How many wastewater treatment plants are there in Arizona?

Klarifi tracks 53 publicly owned wastewater treatment plants in Arizona with a combined average flow of 178 million gallons per day, serving about 2,867,926 residents. 12 of them treat more than 1 MGD and 3 more than 10 MGD.

What is the largest wastewater treatment plant in Arizona?

91st Avenue WWTP in Tolleson is the largest plant in Arizona by average flow, treating about 78.71 MGD.

What treatment technologies are common in Arizona?

25 of Arizona's plants use lagoon systems and 13 have biogas or anaerobic digestion infrastructure, based on Klarifi's aerial imagery review.

How many NPDES permits in Arizona are up for renewal?

9 permits held by Arizona plants expire in 2026 and 12 in 2027. Renewals typically bring new limits and trigger upgrade projects.

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Wastewater Treatment Plants in Arizona

Name: Wastewater treatment plants in Arizona
Creator: Klarifi
License: https://klarifi.io/terms-of-service

53 facilities · 178 MGD combined flow

Klarifi tracks 53 publicly owned wastewater treatment plants in Arizona with a combined average flow of 178 MGD, serving about 2,867,926 residents. 12 plants treat more than 1 MGD and 3 more than 10 MGD; 25 use lagoon systems and 13 have digesters or biogas infrastructure. The largest is 91st Avenue WWTP in Tolleson at 78.71 MGD. 9 NPDES permits expire this year and 12 next year.

Every plant below links to a profile with average and design flow, treatment technology, the NPDES permit and its expiry, a three-year compliance snapshot and the capital projects planned in its city.

53 plant locations in Arizona; dot size follows average flow.

NPDES permits and renewals in Arizona

Every plant discharges under an NPDES permit that is renewed every five years, usually with tighter limits. The renewal year is the year a plant budgets for upgrades.

All NPDES permits in Arizona →9 permits expiring in 2026 →12 permits expiring in 2027 →5 permits expiring in 2028 →Find plants near you on the map →

Largest wastewater treatment plants in Arizona

The 25 largest publicly owned wastewater treatment plants in Arizona by average flow, with NPDES permit, expiry, treatment technology and three-year violation count. Source: EPA ICIS-NPDES via Klarifi.
Facility	City	Avg flow (MGD)	Design (MGD)	NPDES permit	Expires	Technology	Violations (3y)
91st Avenue WWTP	Tolleson	78.71	230	AZ0020524	Apr 2028	Clarifiers, Uncovered lagoons, Carrousels / oxidation ditches, Biogas silos	2
23rd Avenue Wastewater Treatment Plant	Phoenix	35.67	63	AZ0020559	Jun 2029	Clarifiers, Biogas silos	2
Pima County - Ina Road WWTP	Tucson	31.89	50	AZ0020001	May 2027	Clarifiers, Uncovered lagoons, Biogas silos	3
Yuma, City Of - Figueroa Ave WPCF	Yuma	7.27	12	AZ0020443	Aug 2028	Clarifiers, Biogas silos	14
Casa Grande WRF	Casa Grande	3.54	14	AZ0025178	Sep 2029	Clarifiers, Covered lagoons, Uncovered lagoons, Carrousels / oxidation ditches	29
Town Of Prescott Valley - WWTP	Prescott Valley	2.74	3.75	AZ0025381	Feb 2027	Clarifiers, Aerated lagoons, Carrousels / oxidation ditches, Biogas silos	0
Northwest Wrp	Mesa	2.72	18	AZ0024031	Nov 2029	—	6
Goodyear, City Of - 157th Ave WWTP	Goodyear	2.5	7.5	AZ0022357	Mar 2027	Carrousels / oxidation ditches	1
Town Of Buckeye - Sundance Wwrf	Buckeye	2.02	6	AZ0024881	Apr 2029	—	37
Kayenta WWTF	Kayenta	1.46	0.9	NN0020281	Jan 2029	Uncovered lagoons	144
Buckeye WWTP	Buckeye	1.38	4.5	AZ0025313	Oct 2030	Clarifiers, Carrousels / oxidation ditches	1
Cottonwood WWTF	Cottonwood	1.04	1.5	AZ0024716	Apr 2027	Clarifiers	16
City Of Safford - Gila Resources Wrp	Safford	0.78	2	AZ0024911	Jun 2029	Clarifiers, Carrousels / oxidation ditches	0
Chinle WWTF	Chinle	0.71	0.78	NN0020265	Aug 2023	—	160
American Gulch Wastewater Treatment Plant	Payson	0.69	2.75	AZ0020117	Apr 2027	Clarifiers	0
City Of Somerton - WWTP	Somerton	0.65	1.8	AZ0026603	Dec 2029	Clarifiers	0
Whiteriver Sewage Lagoon	Whiteriver	0.58	0.7	AZ0024058	Oct 2026	—	486
Tucson Airport Remediation Project - Co-Mingled Plume	Tucson	0.56	10.2	AZ0026417	Oct 2026	—	0
Joint Venture WWTF	Parker	0.54	1.2	AZ0021415	Nov 2026	Uncovered lagoons	165
Tuba City WWTP	Tuba City	0.42	1.1	NN0020290	Apr 2027	Aerated lagoons, Uncovered lagoons	138
Window Rock Wastewater Treatment Facility	Fort Defiance	0.39	1.2	NN0021555	Sep 2026	Aerated lagoons, Uncovered lagoons	15
Pinal Creek WWTP	Globe	0.35	1.2	AZ0020249	Mar 2031	—	9
Festival Ranch WRF	Buckeye	0.28	1	AZ0025216	Oct 2028	—	3
City Of Peoria	Peoria	0.23	2.25	AZ0024945	Jul 2027	Biogas silos	17
City Of Kingman - Downtown Pond	Kingman	0.23	0.62	AZ0026018	Dec 2026	—	7

The 50 largest plants in Arizona →Arizona capital improvement plans →

Arizona plants by treatment technology

Lagoon systems (25)Activated sludge and clarifiers (24)Oxidation ditches (14)Anaerobic digesters and biogas (13)Chlorine disinfection (12)UV disinfection (7)

All 53 plants in Arizona

Facility	City	Flow (MGD)
91st Avenue WWTP	Tolleson	78.71
23rd Avenue Wastewater Treatment Plant	Phoenix	35.67
Pima County - Ina Road WWTP	Tucson	31.89
Yuma, City Of - Figueroa Ave WPCF	Yuma	7.27
Casa Grande WRF	Casa Grande	3.54
Town Of Prescott Valley - WWTP	Prescott Valley	2.74
Northwest Wrp	Mesa	2.72
Goodyear, City Of - 157th Ave WWTP	Goodyear	2.5
Town Of Buckeye - Sundance Wwrf	Buckeye	2.02
Kayenta WWTF	Kayenta	1.46
Buckeye WWTP	Buckeye	1.38
Cottonwood WWTF	Cottonwood	1.04
City Of Safford - Gila Resources Wrp	Safford	0.78
Chinle WWTF	Chinle	0.71
American Gulch Wastewater Treatment Plant	Payson	0.69
City Of Somerton - WWTP	Somerton	0.65
Whiteriver Sewage Lagoon	Whiteriver	0.58
Tucson Airport Remediation Project - Co-Mingled Plume	Tucson	0.56
Joint Venture WWTF	Parker	0.54
Tuba City WWTP	Tuba City	0.42
Window Rock Wastewater Treatment Facility	Fort Defiance	0.39
Pinal Creek WWTP	Globe	0.35
Festival Ranch WRF	Buckeye	0.28
City Of Peoria	Peoria	0.23
City Of Kingman - Downtown Pond	Kingman	0.23
Quartzsite, Town Of - WWTP	Quartzsite	0.2
Town Of Gila Bend - WWTP	Gila Bend	0.18
Town Of Superior Wastewater Treatment Plant (wwtp)	Superior	0.13
Yuma Main Street Treatment Plant	Yuma	0.12
Town Of Kearny Wastewater Reclamation Facility	Kearny	0.1
Town Of Patagonia - WWTP	Patagonia	0.05
City Of Tombstone - WWTP	Tombstone	0.05
Tusayan Sanitary District	Grand Canyon	0.03
City Of Mesa - Greenfield Water Reclamation Plant	Gilbert	0.03
Winkelman WWTP	Winkelman	0.02
Agua Nueva WRF	Tucson	—
Apache Junction WWTP	Apache Junction	—
Benson, City Of - WWTF	Benson	—
Bullhead City, City Of - Section 10 WWTP	Bullhead City	—
City Of Goodyear - Rainbow Valley WRF	Goodyear	—
City Of Williams - WWTP	Williams	—
City Of Winslow - WWTP	Winslow	—
Ganado WWTP	Ganado	—
North Florence Wwtp, Town Of Florence	Florence	—
Painted Mesa Water Reclamation Facility	Holbrook	—
Pima County - Wwmd - Avra Valley WWTF	Tucson	—
Pima County - Wwmd - Green Valley Bnro - WWTP	Sahuarita	—
Rio De Flag WWTP	Flagstaff	—
Six Mile Lagoon Wastewater Treatment Facility	Peridot	—
Tolleson WWTP	Tolleson	—
Town Of Cave Creek - WRF	Cave Creek	—
Town Of Florence WWTP	Florence	—
Town Of Marana Water Reclamation Facility	Marana	—

Wastewater treatment in Arizona: questions

Sources and methodology

Flow, permit and violation figures come from the EPA's ICIS-NPDES discharge monitoring records. Population served comes from the Clean Watersheds Needs Survey 2022. Treatment structures are identified by Klarifi's review of aerial imagery, and capital improvement projects are extracted from published municipal budget documents. Violations are counted over the last three years of monitoring reports.

Data refreshed September 11, 2026.

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