## Facts

- The Clean Water Act establishes a general prohibition on discharging pollutants from point sources unless the discharge complies with the Act, principally through the NPDES permit program.
- EPA issued NPDES regulations that categorically excluded several classes of discharges it viewed as administratively difficult to permit, including urban storm sewer systems and certain agricultural and silvicultural point sources.
- EPA justified the exclusions on administrative burden, difficulty setting uniform numeric effluent limits, and the view that some discharges resembled nonpoint source pollution better addressed through area-wide planning.
- Environmental organizations challenged the categorical exclusions, arguing the Act requires NPDES permits for all point source discharges unless Congress expressly provides an exemption.
- The district court granted summary judgment for the challengers, holding EPA lacked statutory authority to exempt categories of point sources.
- EPA and regulated-industry intervenors appealed.

## Issues

1. Whether EPA has authority under the Clean Water Act to exempt entire categories of statutory “point sources” from NPDES permitting requirements.
2. Whether administrative burden or difficulty formulating uniform national effluent limits permits EPA to remove qualifying point sources from NPDES coverage.
3. Whether EPA may address difficult-to-regulate point sources through permit conditions other than numeric effluent limits and through general or area permits.

## Decision

- The D.C. Circuit affirmed that EPA lacks authority to create categorical exemptions for point source discharges from the NPDES permit program absent an explicit statutory exemption.
- The court held that the NPDES permit is the exclusive mechanism allowing a point source discharger to avoid the Act’s general prohibition on discharges.
- The court rejected the view that uniform national effluent limits are a prerequisite to including agricultural, silvicultural, and stormwater runoff point sources within NPDES.
- The court stated that administrative or technological difficulty may justify flexible permit administration (including non-numeric conditions), but not exclusion of covered sources.
- The court indicated EPA may use administrative tools such as general or area permits to manage large numbers of similar dischargers.

## Legal Principles

- Discharges of pollutants from point sources are unlawful unless authorized by an NPDES permit; the permitting system is the Act’s exclusive route for lawful point source discharges.
- EPA may not, by regulation, create extra-statutory categorical exemptions from NPDES for classes of point sources; only Congress may enact such exclusions.
- Administrative infeasibility and difficulty setting numeric effluent limitations do not alter statutory coverage; they affect how permits are written and administered.
- Where numeric limits are impracticable, NPDES permits may rely on practice-based requirements (including best management practices) and monitoring and reporting obligations.
- EPA may administer NPDES through mechanisms such as general or area permits to reduce administrative burden while maintaining statutory coverage for point sources.

## Conclusion

The court held that EPA must regulate statutory point sources through the NPDES permit program and may not categorically exempt point source categories based on administrative convenience; flexibility is permitted only through permit design and administrative permitting mechanisms, not through exclusion from permitting.


Natural Res. Def. Council, Inc. v. Costle, 568 F.2d 1369 (D.C. Cir. 1977)