What is a TMDL?

A TMDL, or total maximum daily load calculation is an important tool in maintaining the water quality standards set for water bodies by states, territories, and tribes. Water quality standards identify uses for water bodies, including drinking water supply, contact recreation (swimming), and support for aquatic life (fishing), and then lay out the scientific criteria to support those uses. The federal Clean Water Act, section 303, establishes both the TMDL program and the water quality standards.

A TMDL is a calculation of the maximum amount of a pollutant that a body of water can receive and still meet water quality standards. A TMDL also divides up this maximum pollutant amount among the pollutant's sources including point and nonpoint sources of pollution. The TMDL calculation must include a margin of safety to ensure that the body of water can be used for the purposes the State or other entities have designated through its water quality standards. The TMDL calculation must also account for seasonal variation in water quality.

TMDLs and the Red River in the FM Area

The Red River is the major drinking water supply for the Fargo-Moorhead (FM) area and is also important for recreation and for aquatic life. As shown on the table, TMDLs are under development for three segments of the Red River in the FM area. These TMDLs address issues related to turbidity, ammonia, fecal coliform, pathogens, and organic enrichment that results in low dissolved oxygen. Regulatory agencies and municipal departments in Minnesota (Minnesota Pollution Control Agency, Moorhead Public Works) are working on TMDLs for Segments 1 and 2. Regulatory agencies and municipal departments in North Dakota (North Dakota Department of Health, Fargo Public Works) are preparing TMDLs for Segment 3. Click here to learn more about Water Quality Standards and the Red River.

Segment1	FM River Monitoring Sites2	River Mile (RM)	Description/State Responsible for TMDL development3	Turbidity	Ammonia	Fecal Coliform4	Pathogens5	Organic enrichment, low DO
1	R2	RM 470.2 to RM 448.9	Wild Rice River to Moorhead - Fargo Dam A (MN)	X	--	X	X	--
2	R4, R5, R6	RM 448.9 to RM 427.5	Moorhead -Fargo Dam A to Sheyenne River (MN)	--	X	X	X	--
3	R3, R4, R5, R6	RM 449.3 to RM 417.1	12 Ave N Bridge to confluence with the Buffalo River (ND)	--	X	--	X	X

¹ Informal FM River designation for the Red River TMDL segments ; ² FM River monitoring sites in the Red River TMDL segment ³ EPA description of the Red River TMDL segment and state (ND or MN) responsible for TMDL development ; ⁴ Specific pathogens (related to Fecal Coliform); ⁵ Nonspecific pathogens