Editors' Summary: Water quality standards-based regulation has been the "reserve clause" of the Clean Water Act (CWA), intended to clean up waters that remain polluted after the application of technology standards. For 20 years, these provisions lay idle, prodded forward at least by litigation in the early 1990s. Today, they are at the center of nearly two dozen lawsuits, a Federal Advisory Committee Act committee, and a flurry of regulatory guidance. Their implementation presents serious issues of federalism, science, and political will.

Editors' Summary: For the past quarter century, the Clean Water Act has primarily relied on technological standards to abate point source pollution and achieve national clean water goals. Water quality standards lay largely dormant until the 1990s, when they were activated by citizen suits demanding implementation of §303(d) of the Act—the abatement of pollution discharges based on total maximum daily loads.

Editors' Summary: The Clean Water Act is undergoing a dramatic shift toward water quality-based regulation. Leading the charge, and taking their share of opposing fire, are the long-dormant provisions of §303(d) calling for the development of total maximum daily loads (TMDLs) for impaired waters. Earlier Articles in this series described the legislative and regulatory history of TMDLs, the litigation surrounding them, and the Administration's current efforts to redesign the program. This final Article attempts to step back and assess the potential of the TMDL program.

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.