The United States is on the brink of a new era in water quality regulation. Newly-finalized total maximum daily load (TMDL) rules are bringing to life a long-dormant approach to the identification, prioritization, and repair of the nation's polluted waters that promises to expand the gains in water quality secured by the Clean Water Act's first twenty-five years.(1) Despite progress under the Clean Water Act (CWA), pollution or some form of habitat degradation continues to afflict thirty-six percent of surveyed river miles.(2) Moreover, of the nation's impaired rivers and streams, less than ten percent are impaired primarily or secondarily by industrial point sources -- the Act's principal early target for pollution reductions along with municipal sewage treatment.(3) These stark realities -- along with an abundance of litigation directed at the agency -- have prompted the U.S. Environmental Protection Agency (EPA) to explore the potential of the Clean Water Act's section 303(d) to promote a wide variety of new actions to protect the nation's waters.
A long-neglected part of the Clean Water Act (CWA), section 303(d) requires states to identify waters that are not in compliance with water quality standards, establish priorities, and implement improvements. Based in part upon the recommendations of a Federal Advisory Committee convened in 1996, the EPA issued proposed rules for implementation of the TMDL program in 1999.(4) Amid substantial controversy the final rule was published in July, 2000.(5)
The TMDL rule explains that "[t]he TMDL specifies the amount of a particular pollutant that may be present in a waterbody, allocates allowable pollutant loads among sources, and provides the basis for attaining or maintaining water quality standards."(6) Within this description lies a significant shift in the way water quality is regulated. Instead of the technology-based, end-of-pipe approach to point sources that has characterized CWA enforcement to date, the TMDL program promises an "ambient" approach to water monitoring and standards. That is, instead of a focus on releases from known sources of water pollution (i.e., monitoring discharges from discrete, identifiable pollution sources), regulation and reporting will increasingly be concerned with the in situ quality of waterbodies themselves. While this sounds like simple common sense, an ambient approach to water quality enforcement is largely untried.(7) For a variety of mostly pragmatic reasons, federal and state programs have focused on the regulation of point sources via technology-based standards to secure effluent reductions. But the low-hanging fruit of low-cost, high-volume point source reductions has largely been harvested. Today, significant water quality improvement requires the expansion of controls to nonpoint sources of pollution.
While the rules have significant implications for point sources, the TMDL program's impact on nonpoint source regulation is its most important characteristic. Because ambient monitoring will find a large number of the nation's waterbodies to be impaired, and because nonpoint sources are a primary cause of that impairment, TMDLs will change the politics, economics, and implementation of water quality regulation.
This article provides a description and critical review of the EPA's TMDL rules. The analysis is not critical of the overall movement toward this type of regulatory approach. In fact, TMDL-based rules should be thought of as an inevitable step toward a mature phase of regulation in which all sources of water quality degradation are addressed. However, the review is critical in the sense that it takes a sober view of the significant challenges facing regulators. After all, there is a reason nonpoint sources have largely escaped regulation over the last twenty-five years. Federal authority to mandate nonpoint source controls remains weak. Implementation of the analytic tools required by the TMDL process will be costly and difficult. …