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<br />A verage surface ice thickness, free water depth, water temperature, and dissolved <br />oxygen (D.O.) for 9 backwaters sampled during Trip I (January 6 - 8, 1995) and Trip <br />II (February 6 - 7, 1995) of winter, 1994-95. CH = chute channel, SC = scour <br />channel, ER = eddy return channel. <br /> <br />Table 6. <br /> <br />Site # <br />(River <br />Kilometer) <br /> <br />Reach 1 <br /> <br />1 - CH (533.5) <br />2 - CH (527.1) <br />Reach 2 <br /> <br />3 - SC (511.7) <br />4 - ER (508.8) <br /> <br />Reach 3 <br /> <br />5 - SC (465.6) <br />6 - CH (464.7) <br />7 - SC (418.7) <br />8 - CH (413.7) <br />9 - SC (405.3) <br /> <br />Average Surface' <br />Ice Thickness <br />(cm) <br /> <br />Trip I Trip II <br /> <br />3 <br />21 <br /> <br />15 <br /> <br />3 <br />40 <br />34 <br />34 <br />12 <br /> <br />o <br /> <br />9 <br /> <br />9 <br />18 <br />24 <br />34 <br />6 <br /> <br />Average Free <br />Water Depth <br />(em) <br /> <br />Trip I Trip II <br /> <br />43 <br />43 <br /> <br />30 <br /> <br />34 <br />37 <br />61 <br />98 <br />61 <br /> <br />I Includes both solid surface ice and frazil ice. <br /> <br />37 <br /> <br />49 <br /> <br />21 <br />21 <br />30 <br />73 <br />24 <br /> <br />Average <br />Temperature <br />(OC) <br /> <br />Trip I Trip II <br /> <br />3.10 <br />1.95 <br /> <br />1.38 <br /> <br />0.17 <br />0.16 <br />0.10 <br />0.14 <br />0.18 <br /> <br />2.73 <br /> <br />4.78 <br /> <br />1.21 <br />2.43 <br />2.42 <br />2.95 <br />1.78 <br /> <br />Average D.O. <br />(mg/L ) <br /> <br />Trip I Trip II <br /> <br />5.1 <br />5.3 <br /> <br />16.3 <br /> <br />10.8 <br />10.7 <br />10.4 <br />10.5 <br />10.9 <br /> <br />9.6 <br /> <br />10.9 <br /> <br />11.5 <br />10.0 <br />10.2 <br />9.7 <br />10.7 <br /> <br />Average free water depth in backwaters varied from 21 to 88 em in 1993-94 and from 21 to <br />98 cm in 1994-95. Although ice formed solid to the substrate in shallow areas (<15 em) of most <br />backwaters, we observed ice development extensive enough to substantially reduce free water in only <br />one backwater. More often, ice lenses had collapsed and filled the back ends of backwaters or <br />collapsed and formed an ice plug across the mouth. <br /> <br />Average water temperature in backwaters varied from 0.06 to 3.660C in 1993-94 and from <br />0.10 to 4.780C in 1994-95. Despite measurement of supercooled water temperatures in the <br />mainstem (<00 C), super-cooled conditions were not recorded in backwaters during this study. Frazil <br />ice development was not extensive enough to jam backwaters beneath surface ice and create a super~ <br />cooled condition. <br /> <br />19 <br />