A watershed is the land area that drains to a common waterway. Rivers, lakes, estuaries, wetlands, streams, and oceans are catch basins for the land adjacent to them. Ground water aquifers are replenished by water flowing through the land area above them.
Large aquatic ecosystems (LAEs) comprise multiple small watersheds and water resources within a large geographic area. Currently, EPA defines 10 LAEs. More than 6,000 TRI facilities are located in these LAEs.
The chart below shows the portion of TRI chemical releases within each LAE that were released to air, water, or land, or transferred for disposal off site. Discharges of chemicals to water, as well as releases to air, releases to land, and land disposal, can all affect living resources within an aquatic ecosystem. For example, some chemicals can persist in the environment and accumulate in the tissues of fish and other wildlife. A few chemicals can become more concentrated as predators farther up the food chain eat these organisms, which may ultimately cause health problems for wildlife and humans.
The chart below shows TRI chemical releases per square mile for each LAE. Releases per square mile are greatest in the Gulf of Mexico watershed in the southeastern US, where many chemical manufacturing facilities are located. Almost half of the TRI releases from chemical manufacturing facilities in the US are from facilities located in the Gulf of Mexico watershed.
This page was published in January 2021 and uses the 2019 TRI National Analysis dataset made public in TRI Explorer in October 2020.