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Unit 8: Water Resources // Section 10: Major Laws and Treaties


The central U.S. law regulating water quality is the Clean Water Act (CWA), adopted in 1972. The Act initially focused on point sources, which it regulates through a national program that requires sources to obtain permits for any discharges of controlled pollutants into the nation's "navigable waters." It also increased federal aid to states and localities for sewage treatment facilities. One contentious issue in recent years has been CWA protection for wetlands. Developers have filed multiple lawsuits over issues such as whether isolated and seasonal wetlands fall under the definition of "navigable waters" and whether various types of dredging and filling constitute discharges into wetlands.

The CWA permitting system has substantially reduced water pollution from point sources in the United States, but nonpoint source pollution remains a serious problem. Since the mid-1990s the Environmental Protection Agency has increasingly focused on requirements in the CWA for states to identify "impaired" water bodies (those that remain polluted even after point sources install technical controls) and to develop Total Maximum Daily Load (TMDL) requirements for these systems. Some 20,000 water bodies across the nation fall under this heading (Fig. 17).

Impaired U.S. waters, 2000

Figure 17. Impaired U.S. waters, 2000
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Source: United States Geological Survey.

TMDLs represent the maximum levels of specific pollutants that can be discharged into impaired water bodies from all point and nonpoint sources, including a safety margin. Once states calculate TMDLs they must assign discharge limits to all sources and develop pollution reduction strategies (footnote 16). TMDLs are difficult and expensive to calculate because state regulators need extensive data on all polluters that are discharging into impaired water bodies and must quantify relative contributions from all sources to total pollution.

The Safe Drinking Water Act (SDWA), enacted in 1974, regulates contaminants in public water supplies, which serve about 90 percent of the U.S. population. The law sets mandatory limits on some 90 contaminants to protect public health and recommends voluntary standards for other substances that can affect water characteristics such as odor, taste, and color (footnote 17). The SDWA has significantly improved the quality of drinking-water supplies, but new issues are still emerging. For example, methyl tertiary butyl ether (MTBE), an additive widely used to improve combustion in gasoline, has contaminated public water supplies in many regions where gasoline has leaked from underground storage tanks. The EPA has issued a drinking water advisory for MTBE because small amounts can cause discoloration and odor that make water unpotable, but has not yet set a drinking water standard for MTBE even though the agency's Office of Research and Development calls MTBE "a possible human carcinogen." As of 2004, 19 states had acted independently to ban or limit use of MTBE (footnote 18).

At the international level, the United Nations Convention on the Law of the Sea (LOS Convention), finalized in 1982, creates a comprehensive framework for nations' use of the oceans. The convention outlines each country's rights and responsibilities within its territorial boundaries and in international waters for issues including pollution control, scientific research, resource management, and seabed mining. Coastal states have jurisdiction to protect the marine environment in their Exclusive Economic Zones (areas typically extending 200 miles outward from shore) from activities including coastal development, offshore drilling, and pollution from ships.

The United States is not among the 149 nations that have ratified the convention, which President Reagan refused to sign in 1982, citing restrictions on deep seabed mining that were later renegotiated to address U.S. concerns. Two expert commissions and many stakeholders have called for the United States to ratify the pact (footnote 19). The United States is a party to a number of other international treaties and agreements that regulate ocean activities, including agreements on dumping pollutants at sea, protecting the Arctic and Antarctic environments, regulating whaling, and protecting endangered species.

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