Entergy Corp. v. Riverkeeper, Inc.
The Supreme Court ruled that the EPA may compare costs and benefits when setting rules for power-plant water intake structures that kill fish and other aquatic life, reversing a lower court that had barred that kind of analysis.
The decision gives the EPA more flexibility to avoid mandating the most expensive fish-protection technology when its environmental payoff is only marginally better than cheaper alternatives, shaping how federal regulators can balance industry costs against ecological protection nationwide.
“But “best technology” may also describe the technology that most efficiently produces some good.”
Explaining why 'best technology' can mean cost-efficient, not just maximally protective.
How it got here: The Second Circuit set aside the EPA's cooling-water intake rules and remanded them, ruling cost-benefit analysis was impermissible; the EPA and industry groups asked the Supreme Court to review that ruling.
The Case in Depth
What happened
Large power plants draw huge volumes of water from rivers and lakes to cool their equipment, killing billions of fish and shellfish each year by trapping them against intake screens or sucking them into the cooling system. The EPA wrote rules under the Clean Water Act setting how much this environmental harm existing plants must reduce, but declined to require the most protective (and expensive) technology, instead weighing costs against environmental benefits. Environmental groups and states sued, arguing the law forbids that kind of cost-benefit weighing.
The question before the Court
Can the Environmental Protection Agency weigh costs against environmental benefits when deciding how much power plants must reduce fish deaths from their water-intake systems?
Why it matters
Power companies operating cooling-water intake systems will not be forced to install the costliest technology (like fully enclosed cooling towers) if cheaper options achieve nearly comparable environmental results. This keeps compliance costs lower for utilities and, by extension, electricity customers, while giving the EPA continued discretion to set nationwide fish-protection standards case by case.
What changes now
The case is sent back to the lower courts for further proceedings consistent with the Supreme Court's ruling that cost-benefit analysis is allowed. The EPA's Phase II rules, which had been suspended while litigation continued, can now be reconsidered by the agency and the Second Circuit on the other grounds the appeals court had also cited for its earlier remand, which the Supreme Court did not address. This is a final decision on the cost-benefit question, though other issues about the specific regulations remain open on remand.
What this does not decide
The Court decided only that cost-benefit analysis is not categorically forbidden under this provision; it did not decide whether the EPA's specific 'significantly greater than' cost-benefit standard is itself reasonable, nor did it address other grounds on which the Second Circuit had separately faulted the EPA's rules.
Concurrences and dissents
Concurrence in part — Justice Breyer
Justice Breyer agreed that the EPA may compare costs and benefits, but argued the statute's drafting and legislative history show Congress meant to restrict, not just permit, such comparisons. He also thought the EPA had not adequately explained why it switched from its old 'wholly disproportionate' cost standard to a new 'significantly greater than' standard, and would have let the Second Circuit send that specific issue back to the agency for a better explanation.
Dissent — Justice Stevens
“Section 316(b) neither expressly nor implicitly authorizes the EPA to use cost-benefit analysis when setting regulatory standards; fairly read, it prohibits such use.”The core of the dissent's disagreement with the majority's reading of the statute.
Justice Stevens argued the statute's plain text and its contrast with neighboring Clean Water Act provisions show Congress deliberately withheld cost-benefit authority for this rule, unlike other provisions where it expressly granted that authority. He pointed to the EPA's own cost-benefit calculations as skewed, since the agency valued only a small fraction of affected fish species, and would have held the EPA had no authority to use cost-benefit analysis here at all.
How the Court got there
The legal reasoning, step by step
- The Court applied Chevron deference — the rule that a reasonable agency reading of an ambiguous statute controls even if it isn't the interpretation a court would have picked on its own — to decide whether the EPA's approach was permissible.
- The Court read the phrase 'best technology available for minimizing adverse environmental impact' as ambiguous: 'best' could mean the technology producing the greatest environmental reduction, or the technology producing a good most efficiently relative to its cost, and 'minimizing' does not necessarily mean achieving the maximum possible reduction.
- Comparing this cooling-water provision to four other Clean Water Act pollution-control standards that come with explicit lists of factors the EPA must weigh (some allowing cost-benefit balancing, some allowing only cost consideration), the Court found this provision uniquely lacks any such list, suggesting Congress left the EPA more discretion here rather than less.
- The Court rejected the argument that Congress's silence about cost-benefit analysis in this provision, contrasted with express authorization elsewhere in the statute, must mean Congress intended to forbid it — reasoning that this logic would just as easily forbid the EPA from considering any factors at all, which cannot be right.
- The Court concluded that because even the challengers conceded the EPA need not force industry to 'spend billions to save one more fish,' some balancing of costs and benefits is already accepted as permissible, and there is no textual basis for limiting that balancing to only trivial-benefit cases.
Doctrinal impact
Cases affected by this decision
Reaffirms Chevron U. S. A. Inc. v. Natural Resources Defense Council, Inc. (467 U. S. 837)
The Court applied Chevron's rule that a reasonable agency reading of an ambiguous statute controls.