To protect freshwater resources and reduce the Dead Zone in the Gulf of Mexico by advancing development of protective numeric nitrogen and phosphorus criteria in states and reducing nitrogen and phosphorus pollution in the Mississippi River Basin.

The Situation
The Problems
The Solutions
What is MRC Doing to Reduce Nitrogen & Phosphorus Pollution?


Simply stated, nitrogen and phosphorus (primarily from animal waste, fertilizer runoff, and sewage treatment plant discharges) are killing our waterways. Excessive nitrogen and phosphorus can harm drinking water supplies; it is toxic to plants, wildlife, and small pets; it creates mass fish kills; and it closes beaches and other recreational areas.

The problem can be found throughout the world, but it is especially critical in the Mississippi River Basin because of the amount of agriculture near our rivers, lakes, and streams. Wisconsin River Not only that, but the entire Mississippi River and its tributaries flow directly into the Gulf of Mexico, where an enormous Dead Zone – a direct result of nitrogen and phosphorus pollution – develops annually.

The federal Clean Water Act establishes a good foundation for water quality protection throughout the US, but in the area of nitrogen and phosphorus pollution, it is dangerously insufficient due to the prevalence of unregulated sources (primarily agriculture). To understand the problem facing the Mississippi River Basin, one must start with some basic definitions.

Narrative vs. Numeric Standards. The federal Clean Water Act places the majority of responsibility for classifying water uses – and developing water quality standards to protect those uses – on individual states which have adopted both narrative (e.g., “waters shall be virtually free of”) and numeric (e.g., “cadmium cannot exceed 10 micrograms per Liter”) standards for water quality.

To regulate pollution in waterways, states primarily use Total Maximum Daily Load (TMDL) reports and National Pollutant Discharge Elimination Systems (NPDES) permits.

TMDLs. Every two years, state are obligated under the Clean Water Act to evaluate their waterways and submit to the EPA a list of impaired or threatened waters, called a 303(d) list. For each one of these waterways, the state must develop a Total Maximum Daily Load (TMDL) that establishes the maximum amount of a particular pollutant the waterway can absorb and still meet water quality standards. TMDLs include pollution reductions needed from specific and categorical sources.

NPDES Permits. Some corporations and municipalities discharge treated waste into waterways as part of their operations. For example, a sewage treatment plant takes the sewage from houses or businesses, treats it, and discharges the treated wastewater into a waterway. To do this, the discharger must apply for, receive, and abide by the regulations of a NPDES permit.

With this basic knowledge, one can isolate and examine the main issue facing the Mississippi River Basin.


The problem is nitrogen and phosphorus pollution. But what is causing it? The MRC Nutrients Group has isolated some major factors contributing to the overall problem in the hope that by addressing each individual problem, a collective change can result.

  • Numeric standards for pollutants are generally more effective in protecting water quality than narrative standards since they are less subjective and more readily translated into permit requirements. Surprisingly, most states rely on narrative nitrogen and phosphorus standards alone. EPA has long requested states to prepare numeric standards, but few have done so.
  • Nutrient Reduction Strategies are being developed, often in lieu of numeric standards, and touted by states as their primary effort toward reducing nitrogen and phosphorus pollution. Unfortunately, these strategies are not nearly comprehensive or strong enough to provide any real solution.
  • TMDLs and NPDES permits can be written in such a way that there is ineffective protection for our waters. In addition, enforcement efforts may be too infrequent or even nonexistent.
  • Water Quality Trading has emerged in some areas recently as a new way of dealing with pollution. In such a program, one permitted source is allowed to meet its regulatory obligations by using pollutant reduction credits created by another source. Trading programs must be very carefully constructed so that water pollution “hotspots” are avoided and both agricultural and permitted sources are controlled.
  • Agricultural contributions to nitrogen and phosphorus pollution are not regulated by NPDES permits, nor are necessary TMDL reductions mandatory for the agricultural sector. Read about the efforts of the MRC Agriculture Group to combat this pollution from farms and livestock operations through voluntary measures.

MEA Algae 2 with border


Nitrogen and phosphorus pollution is not isolated, nor is it harmless. While we wait for the EPA to act on what it knows are dangerous levels of nitrogen and phosphorus pollution in our waterways, states need to act on behalf of their citizens and take the steps necessary reduce the amount of nitrogen and phosphorus pollution and protect water quality.

  • NPDES Permits. MRC members and our experts identify weaknesses in the NPDES discharge permits and work with states to remedy them. Areas for improvement include lower pollution limits, increased frequency of water testing, faster compliance times, and better and more frequent enforcement efforts.
  • TMDL Reports. MRC members and our experts identify weaknesses in TMDL studies and seek to incorporate better pollution source identification and concrete implementation measures.
  • EPA Oversight. MRC members engage EPA at the regional and national levels seeking stronger oversight by EPA of state permitting, enforcement, impaired waters listings, TMDL effectiveness, and nutrient criteria development.


The MRC Nutrients Group closely monitors the causes and effects of nitrogen and phosphorus pollution in the waters of the Mississippi River Basin as well as the programs designed by states to combat it. To the extent possible, the MRC Nutrients Group does the following:

  • Advocates for protective numeric nutrient standards by reviewing and pushing for protective standards at the state level, preparing expert testimony on draft proposals, and petitioning and challenging states and EPA for development of numeric standards.
  • Monitors NPDES discharge permits that state agencies grant to dischargers by looking for weaknesses in the nutrient pollution limits to streams and lakes; seeking to improve the frequency of sampling of nutrients, the length of time given for compliance, and to demand protective water quality-based effluent limits; and filing comments, appealing, and/or litigating certain permits based on deficiencies.
  • Analyzes TMDL reports to better protect water quality by examining draft TMDL documents for weakness and insisting agencies incorporate final pollution load limits into permits to protect streams and waterways.
  • Evaluates water quality trading programs by developing criteria to ensure they achieve minimum standards for nitrogen and phosphorus pollution.
  • Consults with EPA on state Clean Water Act programs to discuss state permitting and enforcement and to strengthen the states’ compliance with the Clean Water Act.
  • Educates the public, allies, and partners about the dangers of nitrogen and phosphorus pollution and the urgent need for numeric standards.
  • Serves as experts for media, legislators, regulatory agencies, and advocacy organizations.