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quantifed for the stations on Trout Creek (Table 2.7-9). This data points to the <br />• remarkably similar nature of all four stations with respect to stream width, gradient, <br />depth, and pool To riffle ratios. Percent cover differed, although not greatly, with <br />more cover at Stations 2 and 3. <br />From Station I to Station 2 Oak Creek is a moderately small stream with an <br />average gradient of 1.2%. It flows through o relatively narrow valley and is <br />channelized through much of the study area due to the proximity of the railroad bed <br />and State Highway 131. Where it is not channelized, the stream is well shaded by <br />willows and there are deep pools (to 4 feel) and stable undercut banks providing good <br />fish habitat. General habitat parameters were quantified for Oak Creek in October <br />1979 and are listed in Table 2.7-10. <br />This quantification points to the effects of channelization in the vicinity of <br />Station I. Although the specific stream reach established as Station I had not been <br />channelized, the area both upstream and downstream had been during construction of <br />the railroad and highway. The stream at this station has a higher gradient, is less <br />wide and deep and has less cover. Station 2 is probably closer to what Oak Creek <br />would be like if undisturbed; a wider, deeper, lower gradient stream with a heavy <br />growth of riparian vegetation. <br />• Just as the previous parameters are important measures of fish habitat, the <br />substrate size of the stream bed is important to the invertebrates, which are the <br />food source of fish. In Trout Creek the riffle sections are primarily rubble or cobble <br />sized rocks with a mixture of boulders, gravel and sand. This rubble provides good <br />habitat for the benihic invertebrates (organisms living on the stream bed) by <br />providing numerous "microhabitots" such as rock surfaces and spaces between rocks <br />(where food collecls). It's these microhobitots that become filled when excessive <br />sediment enters a stream, effectively smothering organisms using this space. Rather <br />than the quiet pools with fine substrate and lower current, the majority of the <br />macroinvertebrate species living in Trout Creek prefer the shallower, more turbulent <br />riffle sections (Winget and Mangum 1979). In these sections primary production by <br />algae is greater, due To increased illumination by sunlight with the shallower water. <br />Algae are on important food for the aquatic insects. Another significant food source <br />for the insects are dead leaves from the willows and grasses along the bank. These <br />leaves collect in the riffles on rocks or logs where they are then available to the <br />insects. Here we see the importance of maintaining good growth of willows along <br />• the stream not only for fish habitat, but also as a food source for the aquatic insects. <br />2.7-40 <br />