Surface water assessment

Colorado’s 303(d) listing methodology provides a framework for determining attainment or nonattainment of assigned numeric water quality standards and designated uses. The 303(d) listing methodology is reviewed and updated every two years in anticipation of 303(d) List and Monitoring and Evaluation (M&E) List Development.

Assessment methods and tools

Most assessment methods we use are included in the 303(d) listing methodology linked above. We also use the following resources: