Setting nutrient reduction goals
A Total Maximum Daily Load (TMDL) is a calculation of the maximum amount of a specific pollutant that a waterway can receive and still meeting Federal water quality standards. This is often termed a “pollution diet”.
Every two years under the Clean Water Act, each of the six states (Delaware, Maryland, New York, Pennsylvania, Virginia, and West Virginia) and DC must identify waterways that are “impaired”. Then they must develop TMDLs for each waterway. Most of the Chesapeake Bay and its tidal waters are listed as impaired because of excess nitrogen, phosphorus, and sediment.
Once these waterways are identified and TMDLs developed, the states create management plans to reduce the pollution.
The Chesapeake Bay TMDL provides guidelines for restoring the health of the Bay’s waters by defining pollution reduction goals for nitrogen, phosphorus, and sediment. Under the TMDL, all practices needed to restore the Bay’s health must be in place by 2025.