DEQ extensively tests Virginia's rivers, lakes and tidal waters for pollutants. More than 130 pollutants are monitored annually to determine whether the waters can be used for swimming, fishing and drinking. Waters that do not meet standards are reported to the citizens of Virginia and the U.S. Environmental Protection Agency in the Virginia Water Quality Assessment 305(b)/303(d) Integrated Report.

DEQ has developed lists of impaired waters in every even year since 1992. This impaired waters list individually describes segments of streams, lakes and estuaries that exhibit violations of water quality standards. The report details the pollutant responsible for the violations, and the suspected cause and source of the pollutant. Since 1998, DEQ has developed plans, with public input, to restore and maintain the water quality for the impaired waters. These plans are called "total maximum daily loads," or TMDLs. TMDL is a term that represents the total pollutant a water body can assimilate and still meet standards.

As the lead Nonpoint Source Agency for Virginia, DEQ must maintain a robust Nonpoint Source Pollution Management Program for Virginia. Watershed Roundtables are a key DEQ partner in protecting and restoring water quality in Virginia waters.