Watershed Management Bureau

  Surface Water Quality Assessments [305(b) and 303(d)]

    Consolidated Assessment and Listing Methodology (CALM)

The Consolidated Assessment and Listing Methodology (or CALM) describes, in detail, the process used to make surface water quality attainment decisions for 305(b) reporting and 303(d) listing purposes. The term "listing" refers to the process of placing (or listing) a water on the Section 303(d) List of impaired waters. The CALM also includes descriptions and definitions of the many terms used in the presentation of assessment results; consequently all are encouraged to review the CALM prior to reviewing the assessments as it will help one to better understand and interpret assessment results.

It is important to understand that assessment methodologies are dynamic and likely to change as new information and assessment techniques become available. Such changes can also impact monitoring strategies designed to determine if waterbodies are attaining water quality standards. Periodic updates of the methodology will hopefully result in even more accurate and reliable assessments and, therefore, better management of water resources in the future.

View the most recent version of the CALM.