Summary

Description

The SacramentoSan Joaquin Delta is formed at the confluence of the southflowing Sacramento River and the northflowing San Joaquin River. The Delta provides habitat to many species of aquatic wildlife, including the federallylisted, threatened Delta smelt Hypomesus transpacificus and Sacramento winterrun chinook Oncorhynchus tschawytscha and the proposedthreatened longfin smelt Spirinchus thaleichthys and Sacramento splittail Pogonichthys macrolepidotus. Many fisheries are in a rapid decline in the Delta, smelt populations are estimated to have declined approximately 90 in the last 20 years, and water contamination is one suspected cause. This report summarizes the results of three studies conducted by the U.S. Fish and Wildlife Service between 1994 and 1995. Biologists surveyed water and fish for metals, trace elements, and organics from the Sacramento and San Joaquin Rivers, to evaluate potential metal and trace element loading, and performed toxic identification evaluations TIEs on water from the back sloughs of the Delta. The studies were scoping in nature, designed to screen for potential problems and define the direction and focus of future investigations.