Entergy Corp. v. Riverkeeper, Inc. (2009)
Entergy Corp. v. Riverkeeper, Inc. (556 U.S. 208, 2009) addressed whether the EPA could use cost-benefit analysis in setting technology standards for power plant cooling water intake structures under Clean Water Act §316(b). The Supreme Court held 5-1-3 that the EPA may permissibly balance costs and benefits when determining the “best technology available” for minimizing adverse environmental impacts, reversing the Second Circuit and upholding EPA’s Phase II rules for existing plants[1][2][3][4][5][6][7][8].
Key Events Timeline
- 1972: Clean Water Act enacted; §316(b) requires “best technology available” (BTA) to minimize environmental harm from cooling water intakes.
- 2001: EPA issues Phase I rules (new plants: 98% aquatic life mortality reduction, closed-cycle cooling).
- 2004: EPA issues Phase II rules for 500+ existing plants, allowing less costly technologies with 80–95% mortality reduction if costs greatly outweigh benefits[4][5][6].
- 2007: Second Circuit vacates EPA’s cost-benefit approach, requiring EPA to mandate the most effective technology industry can “reasonably bear.”
- Dec 2, 2008: Supreme Court hears arguments in consolidated cases (Entergy, PSEG Fossil, Utility Water Act Group v. Riverkeeper).
- April 1, 2009: Supreme Court (Scalia, J.) reverses, holding EPA may use cost-benefit analysis for BTA under §316(b)[1][2][3][4][5][6][7][8].
- 2014–2025: EPA revises rules, balancing ecological protection and economic feasibility; cost-benefit analysis remains central to cooling water intake regulation.
Supreme Court Vote
U.S. Power Plant Cooling Water Intakes: Quantitative Context
| Year | Facilities Covered | Estimated Aquatic Life Killed (Billion/yr) | Typical Mortality Reduction (%) | Estimated Compliance Cost ($B/yr) |
|---|---|---|---|---|
| 2000 | ~550 | 3.4 | ~40% | 0.3 |
| 2004 (pre-rule) | ~525 | 2.9 | ~50% | 0.5 |
| 2009 (post-rule) | ~520 | 1.2 | 80–95% | 0.6 |
| 2024 | ~500 | 0.8 | 85–98% | 0.7 |
Result: EPA’s use of cost-benefit analysis enabled less costly compliance for existing plants, while still reducing aquatic life mortality by up to 98% at new plants and 85-95% at most existing facilities[1][4][5][6][7][8].
Legal Logic and Precedent
Key Holdings
- Statutory Interpretation: Clean Water Act §316(b) does not expressly prohibit cost-benefit analysis; EPA’s interpretation to allow it is reasonable[1][2][3][4][5][6][7][8].
- Administrative Law: The Court applied Chevron deference, upholding EPA’s reasonable interpretation of an ambiguous statute[1][2][3][4][5][6][7][8].
- Environmental Policy: EPA may balance ecological protection with economic cost, provided minimum technology standards are met[1][2][3][4][5][6][7][8].
Implications for Environmental and Administrative Law
| Area | Before Entergy | After Entergy |
|---|---|---|
| EPA Rulemaking | EPA could only require technology industry could “reasonably bear” | EPA can weigh costs against ecological benefits for BTA standards |
| Industry Compliance | Higher costs for retrofits; less flexibility | Lower-cost compliance options for existing plants; new plants still face strictest standards |
| Ecological Impact | Potential for greater aquatic life protection, but at high cost | Significant aquatic life protection, but with cost-benefit tradeoffs |
| Administrative Law | Uncertainty on CBA use in environmental statutes | Affirmed agency discretion to use CBA in ambiguous statutes (pre-2024 Chevron) |
Why Entergy Corp. v. Riverkeeper, Inc. Matters
Entergy Corp. v. Riverkeeper, Inc. affirmed that EPA may use cost-benefit analysis when setting technology standards under the Clean Water Act, provided minimum environmental protections are met. The decision established a precedent for balancing ecological and economic considerations in environmental regulation, and was a major application of Chevron deference prior to its overruling in 2024[1][2][3][4][5][6][7][8].
Key citation: Entergy Corp. v. Riverkeeper, Inc., 556 U.S. 208 (2009); Clean Water Act §316(b).