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<br />OJ2297 <br /> <br />et al, 1980, Stanford and Ward 1991). One year's events can sometimes be tracked for years if <br /> <br /> <br />mixing is unable to penetrate the hypolimnion. <br /> <br /> <br />Late Summer/ Fall SWARM (Saline WARM water): In late summer /early fall the river <br /> <br /> <br />inflow has become very warm and.saline-due..to. the..reduced hydrograph, irrigation return flows <br /> <br /> <br />and greater solubility of salts in the geologic stratum of the watershed. Initially this flow intrudes <br /> <br /> <br />into the spring flood below the lake's surface, but as fall progresses, this mass becomes colder and <br /> <br /> <br />eventually sinks. The late summer salinity plume is convectively mixed with the colder bottom <br /> <br /> <br />hugging flow; which we have dubbed the fall SWARM bottom flow because of it's high Salinity <br /> <br /> <br />and relative WARMth (compared to other bottom layers). Oxygen levels 'are typically low due to <br /> <br /> <br />high oxygen demand from the inflow. This cell of water is the greatest contributor of salinity to <br /> <br /> <br />the hypolimnion on an annual basis. As the SWARM plug flows downlake, it incorporates-- <br /> <br /> <br />through diffusion, dispersion and entrainment --the previous winter's undertlows that have <br /> <br /> <br />remained relatively stagnant since the spring flood first appeared. When this saline mass of water <br /> <br /> <br />reaches the dam (between February and March), it contributes to the state of meromixis if of <br /> <br /> <br />sufficient salinity to resist subsequent mixing. <br /> <br /> <br />Deep Winter FRESCO: During the deepest cold of winter, convective mixing is most <br /> <br /> <br />extensive. In the inflow area, the winter river inflow is at its coldest, most oxygen saturated, and <br /> <br /> <br />saline. This cold saline winter inflow is mixed (convective mixing and entrainment) with the last <br /> <br /> <br />of the spring flood near the inflow. A relatively FRESh plug of the lake's COldest most <br /> <br /> <br />oxygenated water results. The FRESCO bottom flow follows the SWARM plug down the bottom <br /> <br /> <br />of the lake, typically set in motion in January and February. <br /> <br /> <br />The FRESCO's downlake momentum will eventually reach the SWARM which has made <br /> <br /> <br />contact with the dam. The momentum of the FRESCO rocks the hypolimnion like a lever, moving <br /> <br /> <br />the uplake chemocline downward as the chemoc1ine at the dam moves upward. It is at this time <br /> <br />03/06/98 <br /> <br />DRAFT <br /> <br />Page 21 of62 <br />