Editors' Summary: Combined sewer overflows and sanitary sewer overlows present unique problems for regulators. Although these problems were largely ignored until recently, EPA has finally begun to address the significant environmental and public health hazards these pollution sources pose. The author first provides a brief overview of the problems of combined and sanitary sewer overflows and the basis for their regulation under the FWPCA. He next discusses EPA's policy and guidance efforts to date, including the relevant documents' specific requirements and the concerns that shaped them.

Nearly three decades after enactment of the modern Clean Water Act (CWA), efforts to address the largest remaining source of water pollution—runoff and other types of aquatic ecosystem impairment from diffuse activities—remain elusive. Every two years, the U.S. Environmental Protection Agency (EPA) confirms in its biennial National Water Quality Inventory that nonpoint source water pollution, or "polluted runoff," causes the majority of water body impairment throughout the country.

Thirty years in the making, the total maximum daily load (TMDL) program of §303(d) of the Clean Water Act (CWA) has never seemed farther from implementation. As state governments increasingly have flexed their regulatory muscles with respect to the environment, ironically they have shied away—to put it mildly—from their environmental responsibilities under the TMDL program. Their reticence and outright opposition to improving water quality are that much more striking given their adamant insistence in 1972 that this obligation be reserved to and exercised by them.

The U.S. Environmental Protection Agency (EPA) is in the process of redesigning the Clean Water Act's (CWA's) total maximum daily load (TMDL) program. Section 303 of the Act requires states and, if necessary, EPA to: (1) identify waters that do not meet water quality standards; (2) establish the TMDLs for pollutants discharged into these waters that will achieve these standards; and (3) incorporate these loads into state planning. These are of course the classic steps of ambient-based water quality management.

Congress passed the Clean Water Act on October 4, 1972, by overwhelming margins—unanimously in the Senate and with a bare 11 dissenters in the House of Representatives. Rising on the Senate floor that day a full quarter-century ago, Sen. Edmund S. Muskie (D-Me.), chairman of the Senate's Subcommittee on Air and Water Pollution and leader of the Senate's clean water forces, explained with simple gravity why Congress was about to pass by such large margins such a powerful and unprecedented law: