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:

Environmental regulation of pollution in the United States is often maligned as costly and ineffective. Pollution continues to plague and degrade the natural resources in the United States, and U.S. waters in particular. Nonpoint source pollution is currently the most significant source of water pollution, but it is also the most unregulated. While other discharges into U.S. waters have been dramatically reduced since the Federal Water Pollution Control Act (FWPCA) was enacted, nonpoint source pollution—caused most by runoff from agricultural operations—has increased.