USE ATTAINABILITY ANALYSIS (UAA) FOR pH AND TURBIDITY FOR THE CENTRAL VALLEY, CALIFORNIA

The federal Clean Water Act (CWA) 303(d) listing of impaired water bodies results in the need to complete approximately 40,000 TMDLs, many of which are due to exceedances of water quality objectives for metals. However, in completing the associated Use Attainability Studies (UAA) studies and TMDLs for these water bodies, it is critical to have an understanding of the form (or speciation) of the metal. The form in which a metal is present is important because some forms are more bioavailable, or potentially toxic to aquatic life. In general, the dissolved, versus the particulate-bound form of the metal is considered more bioavailable. However, not all dissolved metals forms are bioavailable.This paper presents a comprehensive “state-of-the-art” analysis of metals water chemistry developed as part of a study recently completed for the Sacramento/San Joaquin River Central Valley Basin in California. This analysis involves an assessment of receiving stream and effluent data, and includes a discussion of the fate and transport of metals in stream sediment beds for effluent dominated conditions. This analysis is essential to developing the understanding necessary to conduct meaningful UAAs and related TMDLs for attainability with water quality objectives for metals.