Teton Conservation District (TCD) will determine the benthic algae, macrophyte, and macroinvertebrate community characteristics and rates of stream metabolism in selected reaches of Fish Creek. The project will provide information on annual and seasonal changes in algal communities and the effect on Snake River cutthroat trout. During recent summers, Fish Creek has experienced algal blooms that can interfere with spawning of Snake River cutthroat trout (Oncorhynchus clarki ssp.) that occur in Fish Creek.  Beginning in 2007, TCD and the United States Geological Survey – Wyoming Water Science Center began collecting algal and aquatic plant samples, macrophyte samples, and in-situ water quality samples in order to determine annual and seasonal changes in algal communities and the effect on Snake River cutthroat trout. Objectives of the current agreement between the TCD and the U.S. Geological Survey are to (1) develop an improved spatial and temporal understanding of stream-ground water exchanges, (2) develop a two dimensional ground-water model to describe the ground-water interaction with Fish Creek at three crosssections, (3) determine the benthic algae, macrophyte, and macroinvertebrate community characteristics, and rates of stream metabolism (net rates of primary production and respiration) in selected reaches of Fish Creek, (4) evaluate nutrient concentrations (that influence biological indicators of eutrophication) and their potential sources (using stable isotopes), and (5) use other indicator chemicals (such as caffeine and detergent metabolites) to indicate the presence of anthropogenic compounds in Fish Creek and hydraulically connected ground water. These sources of information are being used to document the existence and extent of algae and anthropogenic chemicals in the stream system, and may help determine if anthropogenic factors are influencing algal and macrophyte communities in Fish Creek. This grant will complete the taxonomy for algae samples collected in 2008 and 2009.  Project partners include Fish Creek watershed landowners.