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48 <br />• increasing flow include pool, deep slow areas, and slow shallow areas. <br />He emphasized that some river sites may not conform to the above <br />relationships due to differences in river morphology. <br />o In steep canyoned areas where little or no flood plain exists, in-channel and <br />off-channel backwater area is maximized at low discharge levels. <br />U.S. Department of the Interior (1987b) reported maximum backwater <br />area to occur at low flow levels in Glen Canyon on the Colorado River. <br />Very little overbank flow occurred due to steep canyon sidewalls, thus <br />off-channel backwaters are few at any water level. <br />o Off-channel backwater formation occurs most extensively when preceding low <br />flows are stable. <br />U.S. Deparment of the Interior (1987b) reported buildup of bars which <br />help form off-channel backwaters to occur fastest and most extensively if <br />flows are not fluctuating on a short-term basis, such as daily fluctuations <br />associated with peaking power production at hydroelectric generating <br />dams. They reported summer to be the most disruptive period in terms <br />of backwater availability and needs of the rare fishes. <br />Colorado squawfish. <br />o Off-channel backwaters required for rearing of Colorado squawfish are <br />maintained by high spring flows. <br />