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<br />002';[10 <br /> <br />not move downlake until the following winter when the SWARM's bottom hugging flow will <br /> <br />entrain it as its flows to the dam. An animated sequence of the longitudinal salinity profiles for <br /> <br />Lake Powell since 1965 can be found at website www.usbr.gov/gces.This demonstrates the inflow <br /> <br />and outflow dynamics under various filling, drought and flood cycles. <br /> <br />c. Side Channel influences <br /> <br />While the most of the side channels have not been examined throughout Lake Powell's history, <br /> <br />the San Juan and Escalante Rivers have been received some attention, primarily with the instigation <br /> <br />of the GCES program. The Escalante River contributes only -5% of the total inflow to Lake <br /> <br />Powell, yet produces a regular and pronounced effect on the main channel salinity and dissolved <br /> <br />oxygen levels (Figs. 8-10). Stagnant conditions and very low oxygen levels frequently produce an <br /> <br />oxygen sag and a salinity peak in the main channel year round, frequently at penstock levels. The <br /> <br />San Juan Arm, on the other hand, has greater discharge rates and does not suffer from the anoxic <br /> <br />conditions found in the Escalante arm. Occasionally the San Juan channel produces a bottom <br /> <br />flowing FRESCO plume in the winter that reaches the main channel of the lake, creating a rise in <br /> <br />oxygen concentrations that does not correspond to cold temperatures arising from the main channel. <br /> <br />3. Historic Patterns seen at Lake Powell <br /> <br />In the following discussion, We found it useful to use a ranking system to compare lake attributes <br /> <br /> <br />and reactions against such outside factors as total inflow or outflow for the year, coldness of winter, <br /> <br />hotness of summer. A table of these rankings is found in the appendix. <br /> <br />a. Filling Period (1963-mid 1970?s) <br /> <br />While Lake Powell did not reach full pool until 1980, by 1973 to 1975 it reached a level of <br /> <br />normal fluctuations. By the mid-1970's most of the indicator parameters (temperature, conductivity <br /> <br />and dissolved oxygen) had stabilized. This early period of filling was characterized by low lake <br /> <br />06/02/98 <br /> <br />DRAFT <br /> <br />pooe n of 62 <br />