This appeal turns on whether the transfer of a pollutant from one navigable body of water to another is a “discharge of a pollutant” within the meaning of the Clean Water Act, 33 U.S.C. § 1362(12). If it is, a National Pollution Discharge Elimination System permit is required. 33 U.S.C. §§ 1311(a); 1342(a). The Act defines “discharge of a pollutant,” but the meaning of that definition is itself disputed. During the course of this litigation, the Environmental Protection Agency adopted a regulation addressing this specific matter. The issue we face, after we dispose of a preliminary Eleventh Amendment question, is whether we owe that EPA regulation deference under Chevron U.S.A., Inc. v. Natural Res. Defense Council, Inc., 467 U.S. 837, 104 S. Ct. 2778 (1984). . . .
The Clean Water Act bans the “discharge of any pollutant” without a permit. 33 U.S.C. §§ 1311, 1342(a)(1). “Discharge” is defined as “any addition of any pollutant to navigable waters from any point source.” 33 U.S.C. § 1362(12). It is undisputed that the agricultural and industrial runoff in the canals contains “pollutants,” that Lake Okeechobee and the canals are “navigable waters,” and that these three pump stations are “point sources” even though they add nothing to the water as they move it along. . . . . The question is whether moving an existing pollutant from one navigable water body to another is an “addition . . . to navigable waters” of that pollutant. The district court decided that it is, but that decision came before the EPA adopted its regulation. . . .
Having concluded that the statutory language is ambiguous, our final issue is whether the EPA’s regulation, which accepts the unitary waters theory that transferring pollutants between navigable waters is not an “addition . . . to navigable waters,” is a permissible construction of that language. Chevron, 467 U.S. at 843, 104 S. Ct. at 2782. In making that determination, we “need not conclude that the agency construction was . . . the reading the court would have reached if the question initially had arisen in a judicial proceeding.” . . . Because the EPA’s construction is one of the two readings we have found is reasonable, we cannot say that it is “arbitrary, capricious, or manifestly contrary to the statute.”
Sometimes it is helpful to strip a legal question of the contentious policy interests attached to it and think about it in the abstract using a hypothetical. Consider the issue this way: Two buckets sit side by side, one with four marbles in it and the other with none. There is a rule prohibiting “any addition of any marbles to buckets by any person.” A person comes along, picks up two marbles from the first bucket, and drops them into the second bucket. Has the marblemover “add[ed] any marbles to buckets”? On one hand, as the Friends of the Everglades might argue, there are now two marbles in a bucket where there were none before, so an addition of marbles has occurred. On the other hand, as the Water District might argue and as the EPA would decide, there were four marbles in buckets before, and there are still four marbles in buckets, so no addition of marbles has occurred. Whatever position we might take if we had to pick one side or the other of the issue, we cannot say that either side is unreasonable.
Like the marbles rule, the Clean Water Act’s language about “any addition of any pollutant to navigable waters from any point source,” 33 U.S.C. § 3362(12), is ambiguous. The EPA’s regulation adopting the unitary waters theory is a reasonable, and therefore permissible, construction of the language. Unless and until the EPA rescinds or Congress overrides the regulation, we must give effect to it.