Waterkeepers Chesapeake generally supports much of the Environmental Protection Agency’s (“EPA”) proposed definition of Waters of the United States under the Clean Water Act. We particularly support the strong scientific grounding in parts of the rule that identify categories of waters that are, by definition, waters of the U.S. or that have a “significant nexus” to waters of the U.S. Waterkeepers Chesapeake urges EPA to strengthen those definitions in accordance with comments from members of the EPA Science Advisory Board (“SAB”) and as detailed in our full comments. Waterkeepers Chesapeake is also, however, very concerned about EPA’s efforts to categorically exclude a large number of waters, often with little grounding in the science and law. Waterkeepers Chesapeake believes categorical exclusions are not dictated by the statute or the case law and are likely to lead to waters being subject to pollution that should be protected. In particular, EPA’s approach to groundwater is plainly not warranted by the science as demonstrated by the many comments on this point by individual members of the SAB. Finally, Waterkeepers Chesapeake objects to EPA continuing to allow mining and coal interests to use our precious water resources as dumping grounds for their wastes through the so-called “waste treatment” exclusion from waters protected by the Clean Water Act.