How many wastewater treatment plants are there in Louisiana?

Klarifi tracks 259 publicly owned wastewater treatment plants in Louisiana with a combined average flow of 205 million gallons per day, serving about 1,968,779 residents. 42 of them treat more than 1 MGD and 4 more than 10 MGD.

What is the largest wastewater treatment plant in Louisiana?

South Wastewater Treatment Plant in Baton Rouge is the largest plant in Louisiana by average flow, treating about 33 MGD.

What treatment technologies are common in Louisiana?

77 of Louisiana's plants use lagoon systems and 12 have biogas or anaerobic digestion infrastructure, based on Klarifi's aerial imagery review.

How many NPDES permits in Louisiana are up for renewal?

18 permits held by Louisiana plants expire in 2026 and 25 in 2027. Renewals typically bring new limits and trigger upgrade projects.

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Wastewater Treatment Plants in Louisiana

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

259 facilities · 205 MGD combined flow

Klarifi tracks 259 publicly owned wastewater treatment plants in Louisiana with a combined average flow of 205 MGD, serving about 1,968,779 residents. 42 plants treat more than 1 MGD and 4 more than 10 MGD; 77 use lagoon systems and 12 have digesters or biogas infrastructure. The largest is South Wastewater Treatment Plant in Baton Rouge at 33 MGD. 18 NPDES permits expire this year and 25 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. Showing facilities 1–200 of 259 by average flow — browse the rest with the page links below.

259 plant locations in Louisiana; dot size follows average flow.

NPDES permits and renewals in Louisiana

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 Louisiana →18 permits expiring in 2026 →25 permits expiring in 2027 →70 permits expiring in 2028 →Find plants near you on the map →

Largest wastewater treatment plants in Louisiana

The 25 largest publicly owned wastewater treatment plants in Louisiana 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)
South Wastewater Treatment Plant	Baton Rouge	33	54	LA0036412	Jun 2029	Clarifiers, Biogas silos, Biogas balloons	20
Jefferson Parish Department Of Sewerage- East Bank WWTP	Elmwood	20.66	33	LA0066630	Jul 2028	Clarifiers, Biogas silos	0
Baton Rouge, City Of	Scotlandville	11	54	LA0036439	Jul 2029	Clarifiers, Biogas silos, Biogas balloons	30
Sewerage & Water Board Of New Orleans Westb Ank Sewage	New Orleans	10.13	10	LA0038105	Nov 2029	Clarifiers, Biogas balloons	1
Jefferson Parish Department Of Sewerage- Marrero WWTP	Marrero	6.19	9.6	LA0042048	Oct 2026	Clarifiers, Biogas balloons	5
Monroe, City Of (wpc Cntr)	Monroe	6.09	—	LAL038741	Dec 2030	Clarifiers, Aerated lagoons, Uncovered lagoons, Biogas balloons	78
Plant B	Lake Charles	5.74	—	LAL036366	Dec 2030	Clarifiers, Carrousels / oxidation ditches	73
Hammond North STP	Hammond	4.87	2.5	LA0032328	Aug 2028	Aerated lagoons, Uncovered lagoons, Carrousels / oxidation ditches	36
Red River Wastewater Treatment Plant	Bossier City	4.48	12	LA0053716	May 2028	Clarifiers, Carrousels / oxidation ditches	0
Lafayette Consolidated Government - Ambassador Caffery STP	Lafayette	4.38	6	LA0042561	Oct 2024	Carrousels / oxidation ditches, Biogas silos	0
St. Bernard Parish - Munster WWTP	Chalmette	3.77	11	LA0040177	Oct 2025	—	2
Northeast Wastewater Treatment Plant	Bossier City	3.76	6	LA0065978	Mar 2026	Clarifiers, Carrousels / oxidation ditches	0
Carrollton Water Purification Plant	New Orleans	3.38	—	LA0000086	Jun 2025	Uncovered lagoons, Biogas silos	53
Ruston, City Of- Northside Wastewater Treatment Plant	Ruston	3.22	4	LA0036323	Jun 2028	Clarifiers, Carrousels / oxidation ditches	81
Slidell, City Of	Slidell	2.95	6	LA0047180	Sep 2030	Clarifiers	3
Shreveport North Regional WWTP	Shreveport	2.71	—	LAL042188	Dec 2030	Clarifiers, Aerated lagoons, Carrousels / oxidation ditches	42
Wards 5 & 8 Joint Sewerage Commision	Patterson	2.55	12	LA0068381	Sep 2030	Aerated lagoons, Uncovered lagoons	99
Denham Springs Wastewater Treatment Facility	Denham Springs	2.39	—	LAL045730	Dec 2030	Clarifiers, Aerated lagoons, Uncovered lagoons, Carrousels / oxidation ditches	207
Lafayette Consolidated Government - East WWTP	Lafayette	2.36	—	LAL036382	Dec 2030	Clarifiers, Carrousels / oxidation ditches, Biogas silos	1
St. Charles Parish Council--Destrehan WWTP	Destrehan	2.27	3.2	LA0073539	May 2027	Clarifiers	0
Thibodaux, City Of- Wastewater Treatment Facility	Thibodaux	2.1	8	LA0032948	Jul 2029	Clarifiers, Aerated lagoons, Biogas silos	77
Opelousas, City Of- Candy Street WWTP	Opelousas	1.98	—	LAL036404	Dec 2030	—	191
Abbeville Wastewater Treatment Facility	Abbeville	1.9	—	LAL039748	Dec 2030	Carrousels / oxidation ditches	1
Broussard, City Of	Broussard	1.68	1	LA0020613	Apr 2031	Uncovered lagoons	19
Jennings, City Of- WWTP	Jennings	1.61	2.5	LA0041769	Oct 2025	Clarifiers, Uncovered lagoons	16

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

Louisiana plants by treatment technology

Lagoon systems (77)Activated sludge and clarifiers (44)Oxidation ditches (25)Anaerobic digesters and biogas (12)

All 259 plants in Louisiana

Facility	City	Flow (MGD)
South Wastewater Treatment Plant	Baton Rouge	33
Jefferson Parish Department Of Sewerage- East Bank WWTP	Elmwood	20.66
Baton Rouge, City Of	Scotlandville	11
Sewerage & Water Board Of New Orleans Westb Ank Sewage	New Orleans	10.13
Jefferson Parish Department Of Sewerage- Marrero WWTP	Marrero	6.19
Monroe, City Of (wpc Cntr)	Monroe	6.09
Plant B	Lake Charles	5.74
Hammond North STP	Hammond	4.87
Red River Wastewater Treatment Plant	Bossier City	4.48
Lafayette Consolidated Government - Ambassador Caffery STP	Lafayette	4.38
St. Bernard Parish - Munster WWTP	Chalmette	3.77
Northeast Wastewater Treatment Plant	Bossier City	3.76
Carrollton Water Purification Plant	New Orleans	3.38
Ruston, City Of- Northside Wastewater Treatment Plant	Ruston	3.22
Slidell, City Of	Slidell	2.95
Shreveport North Regional WWTP	Shreveport	2.71
Wards 5 & 8 Joint Sewerage Commision	Patterson	2.55
Denham Springs Wastewater Treatment Facility	Denham Springs	2.39
Lafayette Consolidated Government - East WWTP	Lafayette	2.36
St. Charles Parish Council--Destrehan WWTP	Destrehan	2.27
Thibodaux, City Of- Wastewater Treatment Facility	Thibodaux	2.1
Opelousas, City Of- Candy Street WWTP	Opelousas	1.98
Abbeville Wastewater Treatment Facility	Abbeville	1.9
Broussard, City Of	Broussard	1.68
Jennings, City Of- WWTP	Jennings	1.61
Bridge City Wastewater Treatment Plant	Bridge City	1.59
St. Charles Parish Council	Hahnville	1.43
Plaquemines Parish Government- Belle Chasse WWTP	Belle Chasse	1.34
Donaldsonville, City Of	Donaldsonville	1.34
Breaux Bridge Wastewater Treatment Plant	Breaux Bridge	1.32
Sewerage District #1 Of Iberia Parish & City Of New Iberia- Tete Bayou WWTP	New Iberia	1.27
Ponchatoula, City Of- Wastewater Treatment Facility	Ponchatoula	1.24
Bastrop Main Wastewater Treatment Facility	Bastrop	1.23
Harahan, City Of	Harahan	1.17
Gretna City Of Wastewater Treatment Plant	Gretna	1.17
Youngsville Wastewater Treatment Facility	Youngsville	1.17
Lafayette Consolidated Government - Northeast WWTP	Lafayette	1.16
Natchitoches, City Of	Natchitoches	1.13
Delhi, Town Of - WWTP	Delhi	1.1
Crowley WWTP	Crowley	1.1
Oakdale, City Of	Oakdale	1.07
Rayville WWTF	Rayville	1.05
Village Of Parks WWTF	Parks	0.92
St John The Baptist Parish- Reserve WWTP	Reserve	0.91
Luling Oxidation Pond	Luling	0.84
Leesville, City Of	Leesville	0.81
Scott Wastewater Treatment Facility	Scott	0.77
Deridder City Of - Deridder Animal Shelter	Deridder	0.7
New Roads, City Of- Wastewater Treatment Plant	New Roads	0.7
Town Of Iowa Sd #1	Iowa	0.65
Town Of Jonesville Water System-Disinfection	Jonesville	0.64
Ville Platte, City Of	Ville Platte	0.64
Marksville, City Of	Marksville	0.6
Town Of Sunset Water System	Sunset	0.56
Franklinton STP	Franklinton	0.56
Thibodaux, City Of- North Thibodaux WWTP	Thibodaux	0.55
Oak Grove, Town Of- WWTP	Oak Grove	0.53
Grambling, City Of	Grambling	0.53
Mo-Dad Utilities, Llc - Live Oak Landing Subdivision	Denham Springs	0.5
Tallulah, City Of- Wastewater Treatment Plant	Tallulah	0.49
St. Tammany Parish Government - Castine Regional Sewage Treatment Plant	Mandeville	0.48
Lake Arthur, Town Of	Lake Arthur	0.48
St Tammany Parish-Cross Gate	Slidell	0.45
Farmerville Waste Water Treatment Plant	Farmerville	0.45
Town Of Jena Water System	Jena	0.44
Winnfield, City Of- Wastewater Treatment Plant	Winnfield	0.44
Vinton, Town Of- Treatment Plant	Vinton	0.43
West St Tammany Regional STP	Madisonville	0.43
Town Of Delcambre WWTP	Delcambre	0.43
Simmesport, Town Of (wwtp)	Simmesport	0.42
Cameron Parish Sewer Dist # 1	Cameron	0.42
Kentwood, Town Of- Wastewater Treatment Facility	Kentwood	0.42
St. Martinville, City Of	St. Martinville	0.42
Gramercy WWTP	Kenner	0.41
Carencro Wastewater Treatment Facility	Carencro	0.41
Clinton Wastewater Treatment Plant	Clinton	0.4
Port Allen Water System	Port Allen	0.4
Springhill, City Of	Springhill	0.4
Greenwood Municipal Wastewater Treatment Facility	Greenwood	0.39
Kaplan STP	Kaplan	0.39
Haughton, Town Of	Haughton	0.39
Westwood Regional STP	Mandeville	0.37
Vermillion Parish Solid Waste Landfill	Abbeville	0.36
Plaquemines Parish Government- Buras WWTP	Buras	0.35
Coushatta Wastewater Treatment Facility	Coushatta	0.34
North Oxidationpond	Jonesboro	0.33
Allen Correctional Center	Kinder	0.3
Homer WWTP	Homer	0.3
Timber Branch Ii STP	Mandeville	0.3
Benton Wastewater Treatment Plant	Benton	0.3
Plaquemines Par (port Sulphur)	Port Sulphur	0.29
Town Of Vidalia Waste Water Treatment Plant	Vidalia	0.28
Riverbend Oxidation Pond - Poydras-Verret Wetland	Chalmette	0.28
Rayburn Correctional Ctr Wastewater Treatment Fac	Angie	0.28
Town Of Mamou WWTF	Mamou	0.27
Jackson, Town Of	Jackson	0.27
Pinecrest WWTP	Pineville	0.26
Livingston Parish Sewer District- Buddy Ellis Road Regional POTW	Denham Springs	0.26
Haynesville Town Of	Haynesville	0.26
Carencro, City Of - Manola Street WTP	Carencro	0.26
Jeanerette, City Of	Jeanerette	0.26
Amite City, Town Of- Amite City STP	Amite	0.26
Town Of Church Point	Church Point	0.25
Garyville WWTP	Garyville	0.24
Ramos Wetland Assimilation	Amelia	0.24
Blanchard, Town Of - Wastewater Treatment Plant	Blanchard	0.24
Sewerage District No. 1 Of Tangipahoa Parish- Bedico Regional Stf	Ponchatoula	0.23
Independence, Town Of- Wastewater Treatment Plant	Independence	0.22
Merryville, Town Of - Wastewater Treatment Facility	Merryville	0.22
Arcadia, Town Of-WWTP	Arcadia	0.21
Colfax Wastewater Treatment Facility	Colfax	0.21
Sterlington, Town Of	Sterlington	0.21
Brusly Wastewater Treatment Facility	Brusly	0.2
Plaquemines Parish Government- Boothville WWTP	Boothville	0.2
Highway 22 STP	Madisonville	0.2
Welsh, Town Of	Welsh	0.2
Town Of St. Joseph WWTP	Saint Joseph	0.19
Town Of Lockport - Lockport Sewer Plant	Lockport	0.19
Town Of Erath WTP	Erath	0.19
Iota, Town Of-Wastewater Treat	Iota	0.18
Mansura, Town Of	Mansura	0.17
Winnsboro, Town Of Winnsboro	Winnsboro	0.17
Carville WWTF	Saint Gabriel	0.17
Town Of New Llano	New Llano	0.17
Pointe Coupee Sd #1 Lagoon	New Roads	0.16
Columbia Heights Wastewater Treatment Facility	Columbia	0.15
Ringgold Water System	Ringgold	0.15
Village Of Maurice - South WWTP	Maurice	0.15
Basile, Town Of WWTP	Basile	0.15
Town Of Jonesboro	Jonesboro	0.15
Many, Town Of	Many	0.14
Roseland Water System	Roseland	0.14
Town Of Rosepine Water System	Rosepine	0.14
Pearl River Municipal STP	Pearl River	0.14
North Monroe Sew District #1	Monroe	0.14
Town Of Urania Water System-Z-Aeration	Urania	0.14
Elton, Town Of-Wastewater Trea	Elton	0.13
Country Club Subdivision WWTP	Thibodaux	0.13
Oberlin, Town Of (stp)	Oberlin	0.13
Covington Country Club Wastewater Treatment Plant	Covington	0.13
Benton Palmetto Park Treatment Plant	Benton	0.12
Lake Providence, Town Of- South Pond WWTF	Lake Providence	0.12
St Tammany Sewer Dist 4 Wastsewater Treatment Facility	Covington	0.12
Town Of Olla Water System	Olla	0.12
Sunshine WWTP	Sunshine	0.12
Town Of Logansport	Logansport	0.11
Maurice, Village Of- Wastewater Treatment Plant	Maurice	0.11
Bernice, Town Of	Bernice	0.11
Northwest Hammond Treatment Facility	Hammond	0.11
City Of Plaquemine Water System	Plaquemine	0.11
Sewer District #7 WWTP	Shreveport	0.11
Dequincy Wastewater Treatment Facility	Dequincy	0.11
Erath, Town Of (wwtp)	Erath	0.11
Boyce, Town Of- Wastewater Treatment Facility	Boyce	0.11
Winn Correctional Center	Winnfield	0.11
Port Barre, Town Of	Port Barre	0.1
Livingston Parish Sewer District - Warsaw Landing WWTP	Springfield	0.1
Suma Crossing STP	Livingston	0.1
Centerville Treatment Plant	Centerville	0.1
Napoleonville Sto	Napoleonville	0.1
Arnaudville WWTP	Arnaudville	0.1
Clarks/grayson Wastewater Treatment Plant	Clarks	0.1
Town Of Woodworth WWTP	Woodworth	0.1
St. Gabriel WWTP	Saint Gabriel	0.09
Sewerage District #1 Of The Parish Of Tangipahoa	Hammond	0.09
Four Corners Treatment Plant	Four Corners	0.08
Town Of Washington Water System	Washington	0.08
Rosethorn WWTP	Lafitte	0.07
Glenmora, Town Of Water Sys	Glenmora	0.07
Town Of Zwolle Water System-Tp #1 @ Elevated Tank	Zwolle	0.07
Southwest Regional Stf	Hammond	0.07
Morganza Water System-Well 003 Treatment Plant	Morganza	0.07
St John Central Wastewater Plant	Edgard	0.06
Folsom, Village Of	Folsom	0.06
Tallow Creek Subdivision STP	Covington	0.06
Town Of Mangham WWTP	Mangham	0.06
Grand Coteau Wastewater Treatment Facility	Grand Coteau	0.06
Mansfield, City Of- Sewage Treatment Facillity	Mansfield	0.06
Morse WWTP	Morse	0.06
Simsboro, Village Of	Simsboro	0.06
Sewer District #2 Of Rapides Parish	Pineville	0.06
Village Of Hessmer Water System-Disinfection	Hessmer	0.06
Madisonville Town Of	Madisonville	0.06
Mermentau, Village Of -WWTP	Mermentau	0.06
Gibsland, Town Of	Gibsland	0.05
Town Of Leonville WWTP	Arnaudville	0.05
Town Of Sarepta - WWTP	Sarepta	0.05
East Mooringsport Water System	Mooringsport	0.05
Town Of Lecompte WWTP	Lecompte	0.05
Town Of Marion	Marion	0.05
Town Of Sibley WWTF	Sibley	0.05
Dry Prong, Town Of	Dry Prong	0.05
Plain Dealing Town Of	Plain Dealing	0.04
Port Of Iberia WWTP	New Iberia	0.04
Grundy Cooper Subdivision WWTP	Alexandria	0.04
Loreauville, Village Of- Municipal Sewer Treatment Plant	Loreauville	0.04
St Mary Parish Water & Sewer Commission #4 WWTP	Charenton	0.04
St Tammany Parish Government-Northlake Behavorial Hospital	Mandeville	0.04
Cloverdale Subd. WTP	Alexandria	0.04
Pleasant Hill, Village Of- Wastewater Treatment Facility	Pleasant Hill	0.04

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Wastewater treatment in Louisiana: 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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