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I I I I I I I I I I I I I I I I I I I SITE 6 (RM 288.8) Site 6 was long downstream oriented chute channel located along the left bank just below the Bonanza Bridge (RM 288.8). This backwater had an area of 1,400 m2 and a maximum depth of 1.8 ft at 1,900 cfs. In January two distinct ice layers had formed in this backwater. The ice layers were separated by approximately 1.0 ft of free water, with the surface layer averaging 0.2 ft thick, and the second submerged layer averaging 0.4 ft. It is hypothesized that ice formed in the backwater in mid December. Then another freeze in early January formed localized ice jams in the mainchannel, backing up water and raising the water surface elevation. The surface ice layer observed in January was formed at this elevated stage and the second submerged layer was formed at the original river stage. Water was observed flowing through the backwater (average velocity 0.5 ftIsec), indicating that ice jams in the mainchannel were diverting water through high water channels. By February the ice jams had cleared and the river had returned to its normal stage. Surface ice covered 90 percent of the backwater with an average thickness of 0.6 ft. With this unusual ice formation and water flow through the backwater, this area was determined to be unsuitable overwinter habitat. .. Baseline 240 feet Area 14,875.659 Bathymetric map of Site 6 (RM 288.8), showing waters edge and 1 ft contour lines. Photographs of Site 6 (RM 288.8) taken October 1994 (top) and January 1995 (bottom).