Water Releases
TRI chemicals released into streams or other water bodies are referred to as “water releases” or "Surface Water DischargesIncludes discharges to streams, rivers, lakes, oceans and other bodies of water. These discharges come from contained sources, such as industrial process outflow pipes or open trenches. Facilities must identify the name of each water body into which the TRI chemical is being discharged. Releases of TRI chemicals due to runoff, including stormwater runoff, are also reportable in this category.". They are regulated by the Clean Water Act, which requires facilities that discharge pollutants into surface water to obtain permits under the National Pollutant Discharge Elimination System (NPDES).
The following graph shows the 10-year trend in the amount of TRI chemicals directly released into water bodies.
Note: This chart excludes natural gas processing facilities which were not required to report to TRI prior to 2022.
From 2014 to 2023:
- Discharges to water: 33 million pounds decrease (-15%), mostly due to reductions in releases of nitrate compounds.
From 2022 to 2023:
- Discharges to water: 11 million pound decrease (-6%) since 2022 driven by reductions in nitrate compounds discharges from facilities in the primary metals and petroleum products sectors.
- Nitrate compounds alone accounted for 90% of total releases of TRI chemicals to water.
- Many sectors release nitrate compounds, but facilities in the food manufacturing sector released the most.
Nitrate compounds are often formed as byproducts during wastewater treatment processes such as the neutralization of nitric acid. They tend to have relatively low toxicity to humans compared to many other TRI compounds. However, nitrate compounds can cause increased algal growth which can lead to oxygen depletion in aquatic ecosystems, a process called eutrophication. See EPA’s Nutrient Pollution webpage for more information about the issue of eutrophication.
This page was published in August 2025 and uses the 2023 TRI National Analysis dataset made public in TRI Explorer in October 2024.