Nevada’s Antidegradation Program
Safeguarding Nevada's Surface Water Quality for Future Generations
In April 2024, the Nevada Division of Environmental Protection (NDEP) passed legislation to formalize Nevada’s Antidegradation Program, aimed at preserving the high quality of the state’s surface waters. This initiative received formal approval from the U.S. Environmental Protection Agency (EPA) in June 2025, reinforcing federal support for Nevada’s commitment to safeguarding its water resources.
The program designates waterbodies into four tiers, each providing a distinct level of antidegradation protection with specific provisions for each category as follows:
Within Nevada, Tier 1 protects water quality for beneficial uses of the water on a parameter-by-parameter basis. Tier 2 protects high-quality waters where data show the quality is better than levels needed to protect beneficial uses. Absent data, a waterbody is assumed to merit Tier 2 protection, as data are collected to confirm whether this level of antidegredation protection is warranted. Tier 2.5 and Tier 3 protect water quality and the special characteristics of waterbodies with the designated beneficial use of “extraordinary ecological, aesthetic, or recreational value” (NAC 445A.122). New discharges that are non-degrading are allowed in Tier 2.5 waters whereas Tier 3 prohibits new discharges.
For More Information
- Implementing Nevada's Antidegragation Program Fact Sheet
- Nevada Antidegradation Regulation R113-22
- EPA Final Approval Letter
- Federal Antidegradation Regulation 40 CFR 131.12
For details on Nevada’s rulemaking process for the antidegradation program, including archived meetings, hearings, documents, and correspondence, visit the Antidegredation Regulation Archive Page
Question or inquiries, please contact:
ndep-sam [at] ndep.nv.gov
Bureau of Water Quality Planning
901 S. Stewart Street, Suite 4001
Carson City, NV 89701