Toxic chemicals are constantly entering the Chesapeake Bay and its rivers and streams via wastewater, agriculture, stormwater, and air pollution. These harmful chemicals, such as mercury, PCBs, and PAHs, do not break down easily and persist in the environment for many years, impacting not just fish and birds, but humans as well.
This map by the Chesapeake Bay Program shows tidal waters that are impaired for part or all of the indicated Bay segment by toxic chemicals based on each state's implementation of the Clean Water Act.

Chesapeake Bay Program