"Is the Chesapeake Bay Total Maximum Daily Load and its cleanup deadline enforceable? The answer is complicated.
TMDLs are required for any “impaired” waterbody — one that does not meet standards set by a state to ensure a waterbody is safe for people and aquatic life.
A TMDL sets the maximum amount of a pollutant that the waterbody can receive and still meet those standards. The Bay TMDL maximum “loads” are established for the pollutants nitrogen, phosphorus and sediment.
The TMDL, often called the Bay’s “pollution diet,” allocates those loads among the states and major rivers that drain into the Bay. It also establishes specific limits for entities with a discharge permit."