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beak <br />It should be pointed out that under normal conditions invertebrate <br />• densities decrease in spring and early summer, due mainly to emergence of <br />insects, increase in late summer and autumn as new instars hatch from eggs, <br />and decline during the winter periods when there is little recruitment <br />(Hynes 1970). Thus, total density estimates derived in this study may be <br />indicative of near annual maxima. <br />The presence of large numbers of net-spinning caddisfly larvae <br />(Hydropsychidae) in the stream usually indicates that there is a substantial <br />amount of particulate material in transport in the water. These organisms <br />build nets and eat the particulate material which is filtered from the <br />water. Such increases are often observed downstream of lakes and impound- <br />ments since outflows from these systems supply substantial food in the form <br />of plankton (Hynes 1970). Several studies reported by Hynes (1970) clearly <br />• show that the presence of lakes and impoundments greatly increased numbers of <br />campodeiform Trichoptera, mainly Hydropsychidae, and also to some extent <br />increase numbers of Ephemeroptera. The clear dominance of these two faunal <br />groups in this study indicates that benthic faunal composition of the North <br />Fork at the permit area may be largely influenced by the enriching effect <br />of outflow from Paonia Reservoir immediately upstream. <br />Although the present macroinvertebrate structure indicates slightly <br />enriched conditions, no evidence of toxic substances or depressed oxygen <br />was found. Rather the data presented here suggest that, in general, water <br />quality conditions in this section of the North Fork Gunnison were good <br />(Table 3.0-1j. <br />t <br />• <br />5-7 <br />