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BIOLOGICAL REPORT 90(5) 43 Stream Habitat Analysis and Instream Flow Assessment: A State-Federal Effort in Arkansas by Danny J. Ebert U.S. Forest Service P.O. Box 1270 Hot Springs, Arkansas 71902 Steve P. Filipek A rkansas Game and Fish Commission #2 Natural Resources Drive Little Rock, Arkansas 71202 and Kelly M. Russell U.S. Forest Service 1765 Highland Avenue Montgomery, Alabama 36107 Recent legislation passed by the Arkansas Legis- lature requires the determination of instream flow requirements for beneficial uses in the State's major rivers. In response to this mandate, the Arkansas Game and Fish Commission and State Department of Pollution Control and Ecology developed the Arkansas Method of instream flow determination for fish and wildlife needs. The Arkansas Method is a modification of the Tennant Method (Tennant 1975, 1976) for instream flow assessment; it uses flow standards for three seasonal periods. Sixty percent of the mean monthly flow (MMF) for November through March is recommended for flushing sedi- ments and shaping channels. Seventy percent of the MMF for April, May, and June is recommended to protect spawning. Fifty percent of the MMF (or median, in some cases) for July to October is recom- mended to maintain water quality and provide habitat conditions conducive to fish growth and pro- duction. The flow standards were developed from information on historic streamflows in Arkansas, field experience and data on stream fishes, and knowledge of natural seasonal processes. Because many of the State's highest quality streams are found on National forests, a cooperative State-Federal study was developed to assess stream flows in relation to fish population abundance, habitat, and water chemistry. Field studies were conducted from 1985 to 1988 in third- through fifth- order streams in the Ozark-St. Francis and Ouachita National Forests. Stream reaches were delineated by channel morphology and substrate, and entire pools or riffles were sampled at least three times each year, corresponding to Arkansas seasonal flows. The structure of the fish community in each habi- tat type was summarized using feeding guilds, per- cent composition per species, and biomass per family group. Stream habitat was surveyed at each site using 24 habitat measurements, and water quality and instream flow measurements were made. The number of species generally increased from head- waters to mid reaches and was in most cases asso- ciated with addition of new species rather than replacement. The majority of species added with increasing stream order were pool species or slow- water, large-channel species. Habitat diversity increased with downstream progression, canopy closure decreased as channels became wider, sub- strate particle size became more heterogenous, and