Trends in Surface Water Discharges

Facilities are required to report the total quantity of Toxics Release Inventory (TRI) chemicals they release to receiving streams or other water bodies. The following graph shows the trend in the pounds of toxic chemicals released to water bodies as reported to the TRI Program.

From 2005 to 2015:

• Surface water discharges decreased by 25% (64 million pounds). Most of this decline is due to reduction in water releases of nitrate compounds, which decreased by 25% (57 million pounds).
• Nitrate compounds are often formed as byproducts during wastewater treatment processes such as when nitric acid is neutralized, or when nitrification takes place to meet standards under EPA’s effluent guidelines. More nitrate compounds are released to water than any other TRI chemical.
• Surface water discharges are often regulated by other programs as well, such as under Clean Water Act National Pollutant Discharge Elimination System (NPDES) permits. A NPDES permit is typically a license for a facility to discharge a specified amount of a pollutant into a receiving body of water under certain conditions.
• Surface water discharges of other TRI chemicals, many of which are more toxic to humans than nitrate compounds, have been decreasing at a faster rate. Releases to water are discussed further in the next few figures starting with water releases by chemical.

In 2015:

• Nitrate compounds alone accounted for 88% of the total quantity of all TRI chemicals discharged to surface waters.

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This page was published in January 2017 and uses the 2015 TRI National Analysis dataset made public in TRI Explorer in October 2016.

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