Current and Past Actions

Existing State law requires the State Environmental Commission (SEC) to adopt regulations establishing water quality standards at a level designed to protect and ensure continuation of the designated beneficial uses of waters of the State (NRS 445A.425). Existing regulations establish such water quality standards (NAC 445A.11704-445A.2234, NAC 445A.303-3049). These standards form the basis of Nevada water pollution control regulations. All WQS revisions, adopted by the SEC and approved by the Nevada Legislative Commission, are incorporated into the Nevada Administrative Code. The U.S. Environmental Protection Agency (EPA) has authority to approve, disapprove, or take no action on the proposed water quality standards regulation for its use under the Clean Water Act (40 CFR 131.5).  

Below is an index of current WQS activities and historic WQS actions. Note: prior to September 1993, water quality standards actions are kept on file within NDEP. 

Questions about these regulations? Can't find what you are looking for?  Please email us at: ndep-sam@ndep.nv.gov 

Current Water Quality Standards Activities 

Colorado River Salinity - LCB File No. R146-24 

LCB file number R146-24 amended chapter 445A of the Nevada Administrative Code (NAC) 445A.11704 - 445A.2234 - Standards for Water Quality. This regulation has been approved by the State Environmental Commission (4/30/2026) and the Legislative Commission (6/30/2026). The regulation relocated the salinity standards for the Colorado River system currently found in NAC 445A.1233 to the applicable designated waters. This regulation also removed Schroeder Reservoir (NAC445A.2182) as a designated water, as this reservoir no longer exists.  Additional non-substantive changes were made for regulatory clarity and consistency.  

This regulatory action will be submitted to EPA for approval for use under the CWA. 

• R146-24 Workshop Summary 

• R146-24 Comments Received and NDEP Responses 

• R146-24 Workshop Presentation Slides (3/10/26) 

• R146-24RP2 Regulation with NDEP Proposed Changes 

• R146-24 Fact Sheet 

• R146-24 Workshop Comment Period Public Notice  

• R146-24 Informational Notice of SEC Hearing 4/30/26 

Regulations Awaiting EPA Approval 

Tributaries to the Las Vegas Wash - LCB File No.  R115-22  

LCB File No. R115-22 amended Chapter 445A of the Nevada Administrative Code (NAC) 445A.11704 – 445A.2234 – Standards for Water Quality.  R115-22 amended the NAC to assign beneficial uses and criteria that are better suited for flood-conveyance tributary channels to the Las Vegas Wash.  

This regulation has been approved through Nevada's rule making process and is awaiting approval by the EPA.  

• R115-22 Comments Received and NDEP Responses 

• R115-22 Workshop Summary 

• R115-22 Public Notice and agenda 

• Petition R115-22 R115-22 Regulation   

• R115-22 Rationale 

Recently Approved Regulations 

Algal Toxin Criteria - LCB File No. R149-24  

LCB file number R149-24 amended chapter 445A of the Nevada Administrative Code (NAC) 445A.11704 - 445A.2234 - Standards for Water Quality. R149-24 added the Recreation Involving Contact With the Water (RWC) beneficial use to the table of standards for toxic materials (NAC 445A.1236) and the analytes microcystins and cylindrospermopsin, including numerical criteria for these analytes, to the table.  

R149-24 was adopted by the SEC on 9/9/2025 and the Legislative Commission on 10/28/2025. R149-24 received EPA approval on 10/21/2026. 

• R149-24 EPA Approval Letter (10/21/2026) 

• R149-24 Workshop Summary and Response to Comments 

• R149-24 Workshop Presentation Slides (8/11/25) 

• R149-24 Regulation 

• R149-24 Fact Sheet 

• R149-24 Rationale 

• 2019 EPA Recommended Criteria for Algal Toxins 

• R149-24 Workshop Notice 

• R149-24 Notice of Public Hearing 

Antidegradation Regulation - LCB File No. R113-22  

The Nevada Division of Environmental Protection (NDEP) has implemented a regulatory measure to adopt an updated Antidegradation Program, establishing clear implementation procedures applicable to all surface waters within the state.  

This regulation was adopted by the SEC on March 21, 2024. The EPA granted formal approval in June 2025. 

For more information on Nevada’s Antidegradation Program, please visit the NDEP Antidegradation Webpage. 

• R113-22 Regulation for Antidegradation LCB File No. 113-22 

• R113-22 EPA Approval Letter, June 2025 

Site-Specific Selenium Criteria - LCB File No. R116-22  

LCB File No. R116-22 amended Chapter 445A of the Nevada Administrative Code (NAC) 445A.11704 – 445A.2234 – Standards for Water Quality.  R116-22 adopted site-specific selenium criteria for segments of the Las Vegas Wash.   

This regulation was adopted by the SEC on June 24,2024 and approved by the EPA in May 2025. 

• R116-22 Comments Received and NDEP Responses 

• R116-22 Workshop Summary 

• R116-22 Public Notice and agenda 

• R116-22 Regulation  Petition R116-22 

• R116-22 Rationale 

• R116-22 EPA Approval Letter, May 2025 

Past Water Quality Standards actions, as managed by the SEC