How many wastewater treatment plants are there in Louisiana?

Klarifi tracks 277 publicly owned wastewater treatment plants in Louisiana with a combined average flow of 281 million gallons per day, serving about 2,055,800 residents. 51 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 41.82 MGD.

What treatment technologies are common in Louisiana?

78 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?

16 permits held by Louisiana plants expire in 2026 and 28 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

277 facilities · 281 MGD combined flow

Klarifi tracks 277 publicly owned wastewater treatment plants in Louisiana with a combined average flow of 281 MGD, serving about 2,055,800 residents. 51 plants treat more than 1 MGD and 4 more than 10 MGD; 78 use lagoon systems and 12 have digesters or biogas infrastructure. The largest is South Wastewater Treatment Plant in Baton Rouge at 41.82 MGD. 16 NPDES permits expire this year and 28 next year.

Every plant below links to a profile with average and design flow, the NPDES permit and its expiry, a three-year compliance snapshot and the capital projects planned in its city. Treatment technology and verified contacts are shown with a free Klarifi account. Showing facilities 1–200 of 277 by average flow — browse the rest with the page links below.

276 plant locations in Louisiana; dot size follows average flow. Boundaries: U.S. Census Bureau.

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 →16 permits expiring in 2026 →28 permits expiring in 2027 →72 permits expiring in 2028 →Find plants near you on the map →

Largest wastewater treatment plants in Louisiana

The 10 largest publicly owned wastewater treatment plants in Louisiana by average flow, with NPDES permit, expiry and three-year violation count. Source: EPA ICIS-NPDES via Klarifi.
Facility	City	Avg flow (MGD)	Design (MGD)	NPDES permit	Expires	Violations (3y)
South Wastewater Treatment Plant	Baton Rouge	41.82	54	LA0036412	Jun 2029	21
Jefferson Parish Department Of Sewerage- East Bank WWTP	Elmwood	28.23	33	LA0066630	Jul 2028	0
Baton Rouge, City Of	Scotlandville	20.18	54	LA0036439	Jul 2029	33
Sewerage & Water Board Of New Orleans Westb Ank Sewage	New Orleans	13.61	10	LA0038105	Nov 2029	1
Wastewater Treatment Plant, Hudson Site	Alexandria	8.46	22	LA0041009	Dec 2030	2
Jefferson Parish Department Of Sewerage- Marrero WWTP	Marrero	8.08	9.6	LA0042048	Oct 2026	5
Monroe, City Of (wpc Cntr)	Monroe	7.62	—	LAL038741	Dec 2030	78
Hammond North STP	Hammond	7.21	2.5	LA0032328	Aug 2028	37
St. Bernard Parish - Munster WWTP	Chalmette	7.08	14.5	LA0040177	Aug 2031	2
Plant B	Lake Charles	6.53	—	LAL036366	Dec 2030	73

Treatment technology for each plant is shown with a free Klarifi account. Create one →

The 50 largest plants in Louisiana →EPA enforcement actions in Louisiana →Louisiana capital improvement plans →

Louisiana plants by treatment technology

Lagoon systems (78)Activated sludge and clarifiers (45)Oxidation ditches (25)Anaerobic digesters and biogas (12)

All 277 plants in Louisiana

Facility	City	Flow (MGD)
South Wastewater Treatment Plant	Baton Rouge	41.82
Jefferson Parish Department Of Sewerage- East Bank WWTP	Elmwood	28.23
Baton Rouge, City Of	Scotlandville	20.18
Sewerage & Water Board Of New Orleans Westb Ank Sewage	New Orleans	13.61
Wastewater Treatment Plant, Hudson Site	Alexandria	8.46
Jefferson Parish Department Of Sewerage- Marrero WWTP	Marrero	8.08
Monroe, City Of (wpc Cntr)	Monroe	7.62
Hammond North STP	Hammond	7.21
St. Bernard Parish - Munster WWTP	Chalmette	7.08
Plant B	Lake Charles	6.53
Lafayette Consolidated Government - Ambassador Caffery STP	Lafayette	5.29
Red River Wastewater Treatment Plant	Bossier City	4.62
Shreveport North Regional WWTP	Shreveport	3.78
Northeast Wastewater Treatment Plant	Bossier City	3.57
Slidell, City Of	Slidell	3.47
Ruston, City Of- Northside Wastewater Treatment Plant	Ruston	3.31
Wards 5 & 8 Joint Sewerage Commision	Patterson	3.17
St. Charles Parish Council--Destrehan WWTP	Destrehan	3.1
Denham Springs Wastewater Treatment Facility	Denham Springs	2.67
Lafayette Consolidated Government - East WWTP	Lafayette	2.58
Opelousas, City Of- Candy Street WWTP	Opelousas	2.52
Thibodaux, City Of- Wastewater Treatment Facility	Thibodaux	2.43
Abbeville Wastewater Treatment Facility	Abbeville	2.33
Bridge City Wastewater Treatment Plant	Bridge City	2.33
Gretna City Of Wastewater Treatment Plant	Gretna	2.25
City Of Gonzales Water System	Gonzales	1.96
Plaquemines Parish Government- Belle Chasse WWTP	Belle Chasse	1.9
Crowley WWTP	Crowley	1.89
Deridder City Of - Deridder Animal Shelter	Deridder	1.86
St. Charles Parish Council	Hahnville	1.82
Luling Oxidation Pond	Luling	1.66
City Of Mandeville	Mandeville	1.64
Covington Sewerage Treatment Facility	Covington	1.62
Sewerage District #1 Of Iberia Parish & City Of New Iberia- Tete Bayou WWTP	New Iberia	1.6
Ponchatoula, City Of- Wastewater Treatment Facility	Ponchatoula	1.54
Jennings, City Of- WWTP	Jennings	1.44
Youngsville Wastewater Treatment Facility	Youngsville	1.42
Delhi, Town Of - WWTP	Delhi	1.41
Donaldsonville, City Of	Donaldsonville	1.4
Natchitoches, City Of	Natchitoches	1.35
Rayville WWTF	Rayville	1.29
St John The Baptist Parish- Reserve WWTP	Reserve	1.29
Harahan, City Of	Harahan	1.28
Wastewater Treatment Plant	Pineville	1.28
Breaux Bridge Wastewater Treatment Plant	Breaux Bridge	1.21
Bastrop Main Wastewater Treatment Facility	Bastrop	1.19
Lafayette Consolidated Government - Northeast WWTP	Lafayette	1.19
Broussard, City Of	Broussard	1.16
Carrollton Water Purification Plant	New Orleans	1.13
Oakdale, City Of	Oakdale	1.1
Leesville, City Of	Leesville	1.09
Tallulah, City Of- Wastewater Treatment Plant	Tallulah	0.96
Village Of Parks WWTF	Parks	0.93
Franklinton STP	Franklinton	0.84
Marksville, City Of	Marksville	0.82
Ville Platte, City Of	Ville Platte	0.77
Vermillion Parish Solid Waste Landfill	Abbeville	0.74
Port Allen Water System	Port Allen	0.74
Town Of Zwolle Water System-Tp #1 @ Elevated Tank	Zwolle	0.73
Plaquemines Parish Government- Buras WWTP	Buras	0.72
New Roads, City Of- Wastewater Treatment Plant	New Roads	0.71
Mo-Dad Utilities, Llc - Live Oak Landing Subdivision	Denham Springs	0.69
Town Of Jena Water System	Jena	0.65
West St Tammany Regional STP	Madisonville	0.65
Carencro Wastewater Treatment Facility	Carencro	0.64
Kentwood, Town Of- Wastewater Treatment Facility	Kentwood	0.63
Jeanerette, City Of	Jeanerette	0.63
Thibodaux, City Of- North Thibodaux WWTP	Thibodaux	0.63
Scott Wastewater Treatment Facility	Scott	0.62
Vinton, Town Of- Treatment Plant	Vinton	0.6
St. Tammany Parish Government - Castine Regional Sewage Treatment Plant	Mandeville	0.59
North Oxidationpond	Jonesboro	0.58
Gramercy WWTP	Kenner	0.57
Plaquemines Parish Government- Boothville WWTP	Boothville	0.57
Kaplan STP	Kaplan	0.56
St Tammany Parish-Cross Gate	Slidell	0.53
Amite City, Town Of- Amite City STP	Amite	0.53
Winnfield, City Of- Wastewater Treatment Plant	Winnfield	0.51
Town Of Delcambre WWTP	Delcambre	0.48
Lake Arthur, Town Of	Lake Arthur	0.48
Haughton, Town Of	Haughton	0.48
Cameron Parish Sewer Dist # 1	Cameron	0.46
Oak Grove, Town Of- WWTP	Oak Grove	0.46
Westwood Regional STP	Mandeville	0.45
Riverbend Oxidation Pond - Poydras-Verret Wetland	Chalmette	0.44
Plaquemines Par (port Sulphur)	Port Sulphur	0.44
Farmerville Waste Water Treatment Plant	Farmerville	0.43
Ramos Wetland Assimilation	Amelia	0.42
Jackson, Town Of	Jackson	0.42
Lake Providence, Town Of- South Pond WWTF	Lake Providence	0.42
Greenwood Municipal Wastewater Treatment Facility	Greenwood	0.41
Independence, Town Of- Wastewater Treatment Plant	Independence	0.41
Ringgold Water System	Ringgold	0.41
Springhill, City Of	Springhill	0.4
Town Of Mamou WWTF	Mamou	0.4
Grambling, City Of	Grambling	0.38
Town Of Iowa Sd #1	Iowa	0.38
Pointe Coupee Sd #1 Lagoon	New Roads	0.38
Town Of Lockport - Lockport Sewer Plant	Lockport	0.37
Clinton Wastewater Treatment Plant	Clinton	0.37
Livingston Parish Sewer District- Buddy Ellis Road Regional POTW	Denham Springs	0.37
Town Of Vidalia Waste Water Treatment Plant	Vidalia	0.36
Coushatta Wastewater Treatment Facility	Coushatta	0.35
Garyville WWTP	Garyville	0.34
Homer WWTP	Homer	0.34
Brusly Wastewater Treatment Facility	Brusly	0.34
Oberlin, Town Of (stp)	Oberlin	0.33
Colfax Wastewater Treatment Facility	Colfax	0.33
Kinder Wastewater Treatment Plant	Kinder	0.32
Pinecrest WWTP	Pineville	0.31
White Castle WWTP	White Castle	0.29
St. Martinville, City Of	St. Martinville	0.28
Town Of Jonesboro	Jonesboro	0.28
Welsh, Town Of	Welsh	0.28
Grand Coteau Wastewater Treatment Facility	Grand Coteau	0.27
Town Of St. Joseph WWTP	Saint Joseph	0.27
Sewer District #7 WWTP	Shreveport	0.27
Rayburn Correctional Ctr Wastewater Treatment Fac	Angie	0.26
Arcadia, Town Of-WWTP	Arcadia	0.26
Blanchard, Town Of - Wastewater Treatment Plant	Blanchard	0.25
Sewerage District No. 1 Of Tangipahoa Parish- Bedico Regional Stf	Ponchatoula	0.25
Many, Town Of	Many	0.25
Timber Branch Ii STP	Mandeville	0.24
Basile, Town Of WWTP	Basile	0.24
City Of Plaquemine Water System	Plaquemine	0.24
Haynesville Town Of	Haynesville	0.23
Suma Crossing STP	Livingston	0.23
Town Of Logansport	Logansport	0.23
Ferriday Wastewater Treatment Facility	Ferriday	0.23
Benton Wastewater Treatment Plant	Benton	0.22
Town Of New Llano	New Llano	0.22
Carencro, City Of - Manola Street WTP	Carencro	0.22
Phoenix Wastewater Treatment Plant	Braithwaite	0.21
Stephensville WWTP	Morgan City	0.21
Highway 22 STP	Madisonville	0.2
Allen Correctional Center	Kinder	0.2
Village Of Maurice - South WWTP	Maurice	0.19
Mansura, Town Of	Mansura	0.18
Town Of Erath WTP	Erath	0.18
Columbia Heights Wastewater Treatment Facility	Columbia	0.18
Erath, Town Of (wwtp)	Erath	0.18
Town Of Urania Water System-Z-Aeration	Urania	0.17
Covington Country Club Wastewater Treatment Plant	Covington	0.17
North Monroe Sew District #1	Monroe	0.17
Carville WWTF	Saint Gabriel	0.17
Southwest Regional Stf	Hammond	0.17
Merryville, Town Of - Wastewater Treatment Facility	Merryville	0.17
Town Of Rosepine Water System	Rosepine	0.17
Town Of Olla Water System	Olla	0.16
Iota, Town Of-Wastewater Treat	Iota	0.16
Centerville Treatment Plant	Centerville	0.16
Benton Palmetto Park Treatment Plant	Benton	0.16
St Tammany Sewer Dist 4 Wastsewater Treatment Facility	Covington	0.16
Livingston Parish Sewer District - Warsaw Landing WWTP	Springfield	0.15
Town Of Church Point	Church Point	0.15
Glenmora, Town Of Water Sys	Glenmora	0.15
Town Of Woodworth WWTP	Woodworth	0.15
Town Of Lecompte WWTP	Lecompte	0.15
Pearl River Municipal STP	Pearl River	0.14
Arnaudville WWTP	Arnaudville	0.14
Morganza Water System-Well 003 Treatment Plant	Morganza	0.14
Bernice, Town Of	Bernice	0.14
Country Club Subdivision WWTP	Thibodaux	0.13
Maurice, Village Of- Wastewater Treatment Plant	Maurice	0.13
Northwest Hammond Treatment Facility	Hammond	0.13
Madisonville Town Of	Madisonville	0.13
Four Corners Treatment Plant	Four Corners	0.12
Plain Dealing Town Of	Plain Dealing	0.12
Folsom, Village Of	Folsom	0.12
Gibsland, Town Of	Gibsland	0.12
Village Of Pine Prarie WWTF	Pine Prairie	0.11
Town Of Jonesville Water System-Disinfection	Jonesville	0.11
Sunshine WWTP	Sunshine	0.11
Town Of Sibley WWTF	Sibley	0.1
Cotton Valley, Town Of	Cotton Valley	0.1
Concordia Parish Sewerage District 1	Ridgecrest	0.1
Caddo Sewerage District #2	Shreveport	0.1
Town Of Jonesboro- East Oxidation Pond	Jonesboro	0.1
Clarks/grayson Wastewater Treatment Plant	Clarks	0.1
Dequincy Wastewater Treatment Facility	Dequincy	0.1
Roseland Water System	Roseland	0.1
Napoleonville Sto	Napoleonville	0.1
Town Of Duson STP	Duson	0.1
Winn Correctional Center	Winnfield	0.1
Rosethorn WWTP	Lafitte	0.1
St. Gabriel WWTP	Saint Gabriel	0.09
Sewer District #2 Of Rapides Parish	Pineville	0.09
Elton, Town Of-Wastewater Trea	Elton	0.08
Winnsboro, Town Of Winnsboro	Winnsboro	0.08
Linwood Subdivision East	Opelousas	0.08
Sewerage District #1 Of The Parish Of Tangipahoa	Hammond	0.08
Facultative Lagoon	Montgomery	0.08
Town Of Sarepta - WWTP	Sarepta	0.08
Town Of Washington Water System	Washington	0.07
Tigerville Wastewater Treatment Plant	Edgard	0.07
Fisher/florien Wastewater Treatment Facility	Florien	0.07
Morse WWTP	Morse	0.07
Village Of Hessmer Water System-Disinfection	Hessmer	0.07
Lake Providence, Town Of- North Pond	Lake Providence	0.07
Town Of Maringouin	Maringouin	0.07

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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 October 26, 2026.

Wastewater terms: WWTP · POTW · MGD · NPDES permit · FOG · Equalization tank · all terms

Cite this page

Journalists, researchers and educators are welcome to quote these figures. Please credit Klarifi as the source and link to this page.

Klarifi. “Wastewater treatment plants in Louisiana.” Updated October 26, 2026. https://klarifi.io/facilities/louisiana

Need a custom cut of the data for a state, a county or a list of plants? Email info@klarifi.io.

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