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minnows. Of the above non -game species, most are relatively tolerant of water with elevated <br />TDS levels. Of the trout species, the brown would be the most tolerant. <br />Prior to highway reconstruction, the Colorado Department of transportation published a final <br />Environmental Impact Statement (Colorado Department of Highways, 1978). The statement <br />briefly discusses the section of the North Fork between Somerset and Paonia Reservoir, and <br />mentions that the Division of Wildlife stocks rainbow trout in this part of the river, and that <br />brown trout, and some northern pike and cutthroat are present. We could not find data to <br />verify that statement. Even though the Department of Transportation placed boulder groups in <br />the river for fish habitat enhancement during highway reconstruction, there apparently have <br />been no follow -up studies to evaluate the success of their efforts. <br />Physical Habitat: <br />Channel Characteristics: <br />The North Fork River consists of a single channel through most of the study area with a <br />relatively uniform gradient. A cobble bar divides the river into two channels in the vicinity of <br />station U3. When the channel cross - sections were measured during mid- November of 1994, <br />water depths ranged from 0 to approximately 60 cm, but were usually 10 to 30 cm. Plots of <br />the channel cross - sections are shown in Appendix 3. The plots indicate a generally flat channel <br />bottom, although this is misleading. The bouldery substrate produced a rough bottom that <br />made wading difficult, and in the upper upstream and lower downstream stations where <br />channelization was more pronounced, depths were less uniform and deeper areas exist close to <br />( the north side of the channel. <br />Mean currents averaged over the entire channel width ranged from 0.35 to 0.67 meters /sec; <br />currents in the thalweg (the deepest part of the channel) ranged from 0.52 to 1.02 meters /sec. <br />Measured current velocities were slightly higher downstream of the discharge than upstream <br />(see Table 4). Bottom sediments in the channel throughout the study area consisted mostly of <br />small boulders and cobbles, usually with a small percentage of gravel and occasionally silt. <br />Station D2, 100 m downstream of the discharge, had the largest percentage of silt (7%), and <br />was the only station where there was any appreciable imbeddedness. Most of the silt was on <br />the north side of the channel, and may have come from Sanborn Creek. Current velocities at <br />this site were the lowest of any of the stations. <br />Stream bank and Riparian Characteristics: <br />Riparian vegetation and unvegetated ground was categorized into 6 cover classes and mapped <br />(see map in Appendix 4). Most of the vegetated ground was covered by riparian shrubs, <br />mainly willows, and mature and immature riparian woodland. Riparian woodland consisted <br />14 <br />