Toxic runoff from agriculture, industry, and suburban development has been identified as a significant contributor to water pollution in the United States. Although the Clean Water Act was enacted in 1972 to regulate discharges into surface waters, enforcement data suggest widespread noncompliance. According to reporting by the New York Times, chemical factories, manufacturing plants, and other facilities violated water pollution laws more than half a million times over a recent five-year period. These violations included failures to report emissions as well as releases of toxic substances at levels regulators associate with increased risks of cancer, birth defects, and other health effects.
Evidence of environmental impact has been documented in aquatic ecosystems. A study conducted by the United States Geological Survey examined tumor prevalence in white sucker fish in several tributaries of Lake Michigan in Wisconsin. Over a three-year period, researchers assessed fish populations in the Sheboygan River and the Milwaukee Estuary, both designated as Areas of Concern under the International Joint Commission’s Great Lakes Water Quality Agreement between the United States and Canada. The study found elevated rates of skin and liver tumors in fish from both Areas of Concern, as well as in one location not formally designated as impaired. White sucker fish feed on bottom sediments, making them a useful indicator species for assessing contamination and ecosystem degradation.
Human health impacts related to water contamination have also been documented. A study published in Reviews of Environmental Contamination and Toxicology estimated that approximately 19.5 million Americans experience illness each year from drinking water contaminated with parasites, bacteria, or viruses. This estimate did not include illnesses potentially associated with chemical contaminants or other toxic substances.
Regulatory coverage of drinking water contaminants remains limited. The Safe Drinking Water Act establishes enforceable standards for 91 substances, while more than 80,000 chemicals are currently in use in the United States. For most of these chemicals, it is unknown whether they enter drinking water supplies, at what concentrations they may be present, or what their long-term health effects might be. This uncertainty reflects the absence of routine monitoring and testing for the majority of unregulated chemicals in drinking water.
