Wyoming completed its 2025 Triennial Review of surface water quality standards, and after some delays, the EPA approved Chapter 1 of the Water Quality Rules & Regulations (effective December 18, 2025), publishing the update to its website in mid-March.
Originally adopted by the state on August 6, 2025, these revisions introduce updates to:
- Waterbody classifications, transitioning to designated uses
- Aquatic life and recreation criteria
- Antidegradation provisions and turbidity benchmarks
- Discharge permitting procedures under WYPDES
With EPA approval finalized, these updates are now in effect for Clean Water Act purposes.
What This Means for Permittees:
Dischargers should take this opportunity to review and align with the updated regulatory framework. Key considerations include:
✅Confirming designated uses and applicable effluent limits
✅Evaluating impacts to permit renewals and monitoring programs
✅Assessing potential implications for use-attainability analyses
✅Reviewing WYPDES permit language and compliance schedules
Wyoming’s updated tools, including its interactive recreation-use map and criteria calculator, can also help determine site-specific applicability.
Important Note:
EPA’s approval did not identify any partial disapprovals of the revised standards. However, approval applies to CWA-regulated waters only (excluding “Indian Country”).
Sources:
• https://www.epa.gov/wqs-tech/water-quality-standards-regulations-wyoming
• https://deq.wyoming.gov/water-quality/watershed-protection/surface-water-quality-standards/triennial-review-of-surface-water-quality-standards/
• https://deq.wyoming.gov/water-quality/watershed-protection/surface-water-quality-standards/
• https://deq.wyoming.gov/water-quality/watershed-protection/surface-water-quality-standards/changes-to-designated-uses/
