San Francisco Bay Delta

Accelerate Water Quality Improvement

EPA is committed to accelerating water quality improvement and minimizing the negative impacts to aquatic life from contaminants and other stressors in the Bay Delta Estuary by working with California Water Boards to strengthen implementation of Total Maximum Daily Load (TMDLs) water quality improvement plans.

TMDLs are an important catalyst for restoring impaired water quality and protecting aquatic life. There are twenty-seven approved TMDLs in San Francisco Bay Delta Watershed and fifteen more under development.

There are nine adopted TMDLs in the Bay Delta Estuary watershed that address contaminants (pesticides and selenium) and stressors (low dissolved oxygen) considered potential contributors to aquatic ecosystem collapse and abrupt fish population declines.  There are also five adopted TMDLs that address mercury and methylmercury which has negative impacts on aquatic life and public health.

EPA will work with the Water Boards to EPA assess TMDL implementation progress, identify water quality improvements and any potential barriers to meeting established water quality targets.  We will start with the nine TMDLs that address pesticides, selenium, and low dissolved oxygen and provide updates on this work on this page.

TMDL Resources