||This project was an extensive literature review of aquatic habitat assessment techniques. The objective was to help water quality investigators and natural resource managers unfamiliar with such techniques to become aware of the methods and current trends in development, and to aid in deciding what techniques might best fit project goals. Approximately 30 methods were summarized and compared. Most methods have been developed by Federal or state agencies and have had the greatest application in the western United States. They are classified here according to a number of mutually interacting categories such as project impact, inventory and general description, stream type, particular fish species orientation, and channel stability. Many of the methods have developed indices or numerical values which can be used for comparisons or evaluation. The U.S. Fish and Wildlife Service is channeling substantial effort into the development of habitat evaluation procedures (HEP), techniques designed for assessing project impacts oriented toward a particular species of interest. Parameters most frequently considered in the reviewed methods have included flow, temperature, water surface, width, turbidity, gradient, velocity, depth, bank stability measures, bottom size distribution, siltation, cover, pool size, attached vegetation, fish and invertebrate types, riparian zone vegetation and shade, and obstructing factors such as waterfalls, dams, and culverts. While many methods, are similarly based on such parameters as substrate, cover, flow, depth, and stream and floodplain morphology, they still vary in effort required and objectives. Thus, the ultimate choice of methods for any purpose including nonpoint source pollution evaluation depends on geographical location, stream type, investigator expertise, economics, and precise project goals.