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beak <br />representative riffle area at each location was sampled with a standard <br />• Surber-type invertebrate sampler with a 0.355u mesh net. Riffle areas are <br />preferred for analyzing community composition because of a relatively <br />greater species diversity and productivity, and hence, likelihood of re- <br />taining pollution-sensitive organisms in these particular areas (Hynes 1970). <br />Three (3) replicate samples, each covering a 0.1 m2 area, were obtained <br />at each site. The contents from each replicate were placed in labeled <br />(:olypropylene containers, stained with Rose Bengal solution, and preserved <br />in 70% isopropyl alcohol for shipment to BEAK's Portland laboratory. Analysis <br />in the laboratory derived information on faunal composition, relative <br />abundance of each taxon, and total density per area sampled. Organisms were <br />separated from inorganic debris using sugar flotation techniques and <br />identified to family level based on the descriptions of Edmondson (1959), <br />• Pennak (1978), Usinger (1968), Mason (1968), and Wiggins (1977). <br />5.2 Results and Discussion <br />All stations sampled supported an abundant and diverse association of <br />benthic macroinvertebrates common to lotic freshwater systems (Hynes 1970). <br />Table 5.0-1 presents a taxonomic list of benthic fauna collected during the <br />November survey and identified to family level. Tables 5.0-2 and 5.0-3 <br />present data on relative abundance (percent numbers) of major faunal groups, <br />and total taxa and mean densities (number/m2), respectively, for each <br />station. <br />At least 24 families (taxa) of macroinvertebrates were encountered. <br />There may have been additional families of nematodes and oligochaetes which <br />• were not identified to the family level. No fewer than 17 of these were <br />5-2 <br />