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. DRAFT . 24-hour period. Maps of the river stretch utilized by the fish as described above were completed for each 24-hour monitoring period. 3.2.3 Crepuscular Monitoring . Each fish during year 2 of this investigation was monitored for 2 hours during dawn or dusk; beginning 1 hour before and ending 1 hour after sunrise or sunset. Movement and habitat use of each fish was recorded during this period to determine if different behavior occurs during these crepuscular periods. Habitat measurements were taken at sites occupied by a fish for longer than 15 minutes. 3.2.4 Test Flow Monitoring . Selected fish were monitored for daylight periods of 8 to 12 hours to determine if scheduled flow releases from Flaming Gorge Dam had any effect on fish position and movement. The fish were monitoring during either an increase in flow of 800 to 4,000 cfs or a decrease of 4,000 to 800 cfs. A full description of arrival times and resultant stage flow levels at different sites downstream of Flaming Gorge Dam is presented later in this report. Detailed maps of habitats were drawn over recent aerial photographs of the Rainbow Park area in an effort to assess aereal habitat changes. . 3.3 HABITAT ME'ASUREMENl'S . Upon completion of a 2-hour, 24-hour, or crepuscular monitoring period, habitat measurements were taken to include water depth, water veloci ty, water temperature, cover, and dominant and secondary substrate at each location where a fish was stationary for 15 minutes or longer. Measurements were taken from either a boat, by wading, or through a hole in the ice at three points relative to the fish; the point of triangulation ('point' measurement), one meter toward the river channel ('out' measurement), and one meter toward the shore (' in' measurement) . . . The 'point' measurements included water depth; water velocity at the river bottom, at 0.2, 0.6, and 0.8 of the water depth; dominant and secondary substrate; and water temperature. Measurements at one meter on either side of the fish ('in' and 'out') were the same except that velocity was recorded only a 0.6 depth. Velocities were measured using a Marsh-McBirney current meter and an 6 to 12-foot wading rod. Where the measurement was taken in a countercurrent (i.e. an eddy) greater than 90 degrees from the main directional flow, velocity was recorded as negative. Substrates was assessed as one of six categories (silt, sand, gravel, cobble, boulder, or bedrock) by probing with the hand, foot, or wading rod, depending on water depth. Features providing cover (i.e. large boulders, overhanging banks, sand ridges) at each location were also recorded. . . 10 .