States are required under the Clean Water Act (CWA) Section 303(d) to compile a list of waters that do not support their designated beneficial uses and submit the list in a biennial Integrated Report to the Environmental Protection Agency (EPA) for approval. Beneficial uses include drinking water, recreation, aquatic life, and agriculture.The 303(d) list identifies the pollutant(s) causing the impairment and prioritizes the development of Total Maximum Daily Loads (TMDLs) to meet state water quality standards and support beneficial uses.
The Draft 303(d) Assessment Methods describe Utah’s proposed process for determining whether waterbodies are/are not supporting their designated beneficial uses in the 2024 Integrated Report cycle. The document complies with federal regulations that require states to evaluate all existing and readily available data against both narrative and numeric criteria when developing their 303(d) lists.
The Draft 2024 Integrated Report 303(d) Assessment Methods were available for public review and comment October 24 to December 8, 2022. DWQ is currently compiling, reviewing, and responding to comments and will publish its responses and a new version of the assessment methods in 2023.
Note: This will be the only opportunity to provide comments on the 303(d) Assessment Methods until the next IR reporting cycle. Any comments on assessment methods received after the close of the current comment period will be considered out of scope for the 2024 Integrated Report.
Final 2024 303(d) Assessment Methods – Changes from previous version and draft
|Section||Subsection||Page Range||Timing of Change||Nature of Change|
|Introduction||Assessed Parameters||14||Draft 303(d) Methods||Changed Assessed and Priority Parameters Section to Assessed Parameters. Removed reference to former Appendix 1, which contained a list of priority parameters. The purpose of this list was unclear, so removed.|
|Assessment Process and Time Frames||Public Review of the 303(d) List||19||Draft 303(d) Methods||Changed timeframe over which TMDLs are completed and reviewed by the Water Quality Board.|
|Scope of the Assessment||Assessment Units||21, 23||Draft 303(d) Methods||Added that river and stream assessment units are reported using perennial stream miles, rather than intermittent and perennial.|
|Data Quality||Components of Credible Data||25||Draft 303(d) Methods||Shortened Example SOPs language.|
|Data Quality||Credible Data Matrices||27-31||Draft 303(d) Methods||Added waterbody type to the essential metadata needed as outlined in the credible data matrices.|
|Data Submission Process||Period of Record||32||Draft 303(d) Methods||Changed period of record for the 2024 IR.|
|Assessments Specific to Rivers, Streams, and Canals||Conventional Parameter Assessments||34||Draft 303(d) Methods||Removed term “instantaneous” from DO conventional parameter assessment notes.|
|Assessments Specific to Rivers, Streams, and Canals||Conventional Parameter Assessments||35||Draft 303(d) Methods||Added clarifying sentence about multiple beneficial use assessments.|
|Assessments Specific to Rivers, Streams, and Canals||Narrative Standards: Biological Assessments||45-47||Draft 303(d) Methods||Rewrote and shortened Biological Assessments section.|
|Toxic Parameter Assessments for all Waters||Equation-Based Toxic Parameters||57||Draft 303(d) Methods||Corrected ammonia criteria equations, which were missing terms from the standards outlined in R317-2.|
|Escherichia coli Assessment for All Waters||Assessment Process||62||Draft 303(d) Methods||Corrected E. coli language to reflect the process outlined in the flow diagram, which was updated in the 2022 IR.|
|Narrative Standards for All Waters||Harmful Algal Blooms (HAB)||66-67||Draft 303(d) Methods||Updated harmful algal bloom section.|
|Narrative Standards for All Waters||Fish Tissue Assessments and Consumption Health Advisories||67||Draft 303(d) Methods||Clarified the definition of a p-value in the fish tissue mercury section.|
|Determinations of Impairment: All Assessment Units||Aggregation of Site-Specific Assessments to Assessment Unit Categories||70||Draft 303(d) Methods||Updated flow diagram used to show how DWQ aggregates from site-specific parameter assessments to an AU-level assessment category.|
|Appendices||Appendix 1||82||Draft 303(d) Methods||Removed appendix containing a list of priority parameters. The list covered most parameters in R317-2, and it was unclear the purpose of the list. Removed to improve methods conciseness and clarity.|
|Appendix 3||Summarizing Assessments From site to Assessment Unit Level||90-93||Draft 303(d) Methods||Rewrote Appendix 3 demonstrating how DWQ summarizes sites to AU-level assessments.|
|Appendix 5||Delisting Guidelines||96||Draft 303(d) Methods||Rewrote Appendix 5 delisting guidelines.|