Tennessee Clean Water Network © 2019

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Nitrogen and Phosphorus Pollution

Nitrogen and phosphorus pollution suffocate our streams. Excessive nitrogen and phosphorus can harm drinking water supplies, is toxic to plants, wildlife, and small pets, and makes our streams unsafe for recreational activities. This is a special concern to TCWN because almost all of the water in Tennessee ends up in the Mississippi River and then the Gulf of Mexico. All the nitrogen and phosphorus pollution in Tennessee contributes to the annual Dead Zone in the Gulf - an area the size of Connecticut void of life due to lack of oxygen.

Nitrogen and phosphorus pollution is a problem in Tennessee’s waters, and it’s a problem that is getting worse. Of the waters assessed for these parameters, 3,375 stream miles are impaired due to nutrients.  In 2004 fewer than 2,000 miles of stream were nutrient-impaired. This is an increase of almost 70% in ten years. 

There are multiple tools available to combat nitrogen and phosphorus pollution, which result most frequently from animal waste, fertilizer runoff, and sewage treatment plants.

TMDLs
 
Total Maximum Daily Loads are watershed plans providing a quantitative limit of how much of a specific pollutant the streams in that watershed can tolerate before becoming polluted. These plans divide the total load the watershed can withstand between all the sources of the pollutant in that watershed. Many experts think these plans are the best tool we have to reduce pollution in our waterways. However, Tennessee only has a handful of these plans for nutrients.  
Permit Limits
 
Proper limits for nitrogen and phosphorus in wastewater treatment plant and other industry permits are necessary to ensure not too much of a pollutant is discharged into our waters. Unfortuantely the state currently fails to include effective limits in these permits and doesn't even base these limits on what the receiving stream can handle before its polluted. 
Numeric Water Quality Standards
 
Tennessee only has a narrative standard for nutrients - no hard number to determine how much is too much nitrogen or phosphorus. 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.