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Kubly 1993). Dislodged material should then be removed with forceps. The scraped area should then be' flushed with water, scrubbed with a brush, and the water and any material removed with a dropper. Ten samples of this type should be collected at each site during each sampling visit. Periphyton samples should be kept cold (< 4 C) and then frozen upon returning to the laboratory. In the laboratory, this material should be thawed, dried at 600C until a constant weight is attained, weighed, and fired in a muffle furnace at 5500C for 2 hours to obtain ash-free dry mass (AFDM). Water Temperature Water temperature should be measured in major habitat types within each reach using electronic temperature recorders (e.g., Onset Instruments, Inc. Hobo-Temp XT units). These units should be programmed to collect data at a minimum of 4 hr intervals. The recorders should be swapped with a fresh unit each time a site is visited. Laboratory Methods Zoobenthos Samples should be processed following Elliott (1971). Initially, the composited sample should be searched for large and less-numerous organisms. If the sample appears to contain more than 250 organisms it should be subsampled. All organisms within a sub-sample should be removed and identified. Additional sub-samples should be taken until a minimum of 250 organisms is removed. Organic matter from the sorted portion of the sample should be combined back with the unsorted portion of the sample and used to determine organic matter composition. An effort should be made to identify organisms to a consistent taxonomic level. A recommended list of taxonomic resolution for the major taxonomic groups is presented in Appendix 1. At a minimum, insects should be identified to the genera level except Chironomidae which should be identified to subfamily. Non-insect taxa can be identified to various taxonomic levels depending on the availability of identification keys. Genera identifications of insects are desired because much of the basic habitat requirements and life history information for insect genera, except Chironomidae, are known. A list of suggested identification keys and references to be used is presented in Appendix 2. Organic Matter Benthic organic matter biomass should be collected as part of quantitative zoobenthos samples. Once the invertebrates have been removed from a sample, the sample should be divided into coarse (> 1 mm) and fine (0.250-1.0 mm) particulate size fractions. This material should be then dried at 60 C until a constant weight is attained, weighed, and fired in a muffle furnace at 550 C for 2 hr to obtain ash-free dry weight. 8