SCOPE OF THE REVIEW This report presents an overview of the scientific literature on chromium in the aquatic environment with emphasis on the most recent information available. It provides a broad critical review of information on analytical techniques to measure chromium in water@ chemistry and fate of chromium in natural waters@ the nutritional role and effects of chromium on human health@ principal sources of chromium in surface water@ the effects of chromium on aquatic organisms@ and important factors which influence chromium toxicity. This document also includes a comparative compilation of aquatic toxicity data@ and state and federal water quality criteria and standards for chromium. Finally@ the regulatory framework and policies regarding the discharge of chromium-bearing wastes from industrial point sources are discussed@ with emphasis on how relevant scientific information on chromium can be used in the process of deriving water quality criteria and standards and in regulating discharges. The information in this review was obtained primarily through computer searches of appropriate databases@ direct communication with individuals in the scientific and regulatory communities@ and reference to recent technical reviews of the chromium literature. The computerized databases used for this effort were BIOSIS Previews (Bio-Science Information Service)@ CA Search (American Chemical Society)@ NTIS (National Technical Information Service)@ Oceanic Abstracts (Data Courier@ Inc.)@ Pollution Abstracts (Data Courier@ Inc.)@ SSIE Current Research (Smithsonian Science Information Exchange)@ Aquaculture (NOAA)@ Aquatic Science and Fisheries Abstracts (NOAA)@ ENVIROLINE (Environment Information Center@ Inc.)@ ENERGYLINE (Environment Information Center@ Inc.)@ and MEDLINE@ TOXLINE@ TDB (Toxicological Data Bank)@ and RTECS (Registry of Toxic Effects of Chemical Substances) from National Library of Medicine.