303(d) Listing Methodology

The 303(d) Listing Methodology provides a framework for determining attainment or non- attainment of assigned water quality standards and designated uses in support of developing Colorado’s 303(d) List of Impaired Waters and the Monitoring and Evaluation List. Every two years, a 303(d) Listing Methodology stakeholder workgroup considers revisions to this document. Monthly workgroup sessions are scheduled from September through November of this year. At the conclusion of this workgroup, the Division will propose revisions to the Listing Methodology that the Water Quality Control Commission will consider through an administrative action hearing. This hearing is scheduled for March 2024.

To participate in this workgroup, please visit the Water Quality Control Division’s engagement website to learn more and sign up: https://cdphe.colorado.gov/water-quality/water-quality- engagement/303d-listing-methodology. Rather than posting 303(d) Listing Methodology workgroup materials to multiple websites, materials will only be posted to the Division’s engagement website.