What is the largest wastewater treatment plant in North Dakota?

Grand Forks City Of in Grand Forks, treating an average of 12.26 MGD under NPDES permit ND0022888. Wahpeton City Of in Wahpeton is second at 8.29 MGD.

How much wastewater do North Dakota’s largest plants treat?

The 13 largest plants treat 53 MGD combined, 100% of the flow reported by all 200 publicly owned plants in North Dakota.

How is plant size measured?

By reported average daily flow in million gallons per day (MGD) from EPA discharge monitoring reports, the standard measure of a plant’s size. Design capacity, the flow a plant is permitted to treat, is usually higher and is shown on each profile.

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The 13 largest wastewater treatment plants in North Dakota

Name: Largest wastewater treatment plants in North Dakota
Creator: Klarifi
License: https://klarifi.io/terms-of-service

Ranked by average flow · 53 MGD combined · 100% of the state's reported flow

Grand Forks City Of in Grand Forks is the largest publicly owned wastewater treatment plant in North Dakota by reported average flow, treating about 12.26 million gallons per day. The 13 plants below treat 53 MGD between them, 100% of the flow reported by all 200 plants in the state, and serve about 293,669 people. Every plant links to its profile with permit and compliance data. Treatment technology is shown with a free Klarifi account.

All plants in North Dakota →The 50 largest US plants →North Dakota NPDES permits →

The 13 largest publicly owned wastewater treatment plants in North Dakota by average flow (MGD), with population served, NPDES permit, expiry and three-year violation count.
#	Facility	City	Avg flow (MGD)	Population	NPDES permit	Expires	Violations (3y)
1	Grand Forks City Of	Grand Forks	12.26	70,278	ND0022888	Dec 2028	7
2	Wahpeton City Of	Wahpeton	8.29	7,802	ND0020320	Sep 2031	5
3	Bismarck City Of (potw)	Bismarck	7.34	75,230	ND0023434	Jun 2028	0
4	City Of Minot - Minot Landfill	Minot	5.03	47,201	ND0022896	Mar 2030	20
5	West Fargo City Of	West Fargo	5	40,494	ND0022616	Sep 2029	4
6	Devils Lake City Of	Devils Lake	3.8	11,697	ND0020681	Mar 2028	77
7	Williston City Of	Williston	2.86	16,988	ND0022349	Mar 2028	4
8	Casselton City Of	Casselton	2.85	2,689	ND0020567	Sep 2029	18
9	New Town Water Resource Recovery Facility	New Town	2.3	—	NDG589108	Mar 2027	1
10	Mandan Landfill / Ts	Mandan	1.69	21,161	ND0022861	Sep 2031	0
11	Medora City Of	Medora	0.68	129	ND0022799	Jun 2031	4
12	Watford City City Of	Watford City	0.64	—	ND0021849	Sep 2030	27
13	Prairie Knights Casino & Resort	Fort Yates	0.04	—	ND0031135	Dec 2023	9

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

Largest plants in North Dakota: 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 · Filter press · FOG · 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. “Largest wastewater treatment plants in North Dakota (2026).” Updated October 26, 2026. https://klarifi.io/facilities/north-dakota/largest

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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