The Department is initiating its Triennial Review of state surface water quality standards as required by the Federal Clean Water Act. Proposed revisions to a number of rules in both Chapters 62-303 and 62-302, Florida Administrative Code (F.A.C), are under consideration, but all surface water quality standards, including those within other F.A.C. chapters, are part of the Triennial Review and are subject to possible revision. Proposed amendments within Chapter 62-303, F.A.C., include: (1) establishment of biological health assessment impairment thresholds, (2) establishment of impairment threshold for fish/shellfish tissue methylmercury levels, (3) new definition for Predominantly Fresh Waters and revision of definition for Predominantly Marine Waters, and (4) addition of prioritization criteria for biological health assessments.