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<br />0023 J2 <br /> <br />term forebay plots in Fig. 3a, denoted by a low inflow (as well as outflow) hydrograph, <br /> <br /> <br />decreasing or low lake levels, and generally increasing salinity levels. Some of the droughts may <br /> <br /> <br />have consisted of only one or two year, such as 1964, 1972, 1976 to 1977 and 1981, yet it can be <br /> <br /> <br />seen theY_biid.lIiLimmediateand persistent effectuponthe hypolimnion. Other droughts continued _...___~___ <br /> <br /> <br />for years, such as the 3 sub-normal years from 1966 through 1968, and the most recent drought <br /> <br /> <br />from 1988 to 1992. These longer droughts produced greater meromixis in the hypolimnion, as <br /> <br /> <br />well as substantially higher levels in the epilimnion. <br /> <br /> <br />As happened in 1966, the effects of a strongly saline SWARM bottom current, such as <br /> <br /> <br />typically follows a dry year, has an immediate and strong influence on hypoIirnnetic conductance. <br /> <br /> <br />Decreasing lake volumes characteristic of drought cycles exacerbated the concentration of salts in <br /> <br /> <br />the lake. Dissolved oxygen levels, on the other hand, could be elevated during drought iflake <br /> <br /> <br />levels dropped sufficiently to allow the winter oxygen plume a shorter approach to the dam. <br /> <br />Rapid releases that are not accompanied by matching inflow volume will result in a drop in <br /> <br />lake elevation. At this time, water stored in the more eutrophic side bays enter the mainstem <br /> <br /> <br />(Thorton et al. 1990). This process will contribute to meromixis during drought periods. <br /> <br /> <br />While the data during the 80's flood was compromised, the temporal resolution dwindled to 1 <br /> <br /> <br />or 2 trips per year for 4 years from 1988 to 1991. Inflow volumes indicate these were drought <br /> <br /> <br />years, but little information can be garnered from this period except a 5 year trend. While trends <br /> <br /> <br />manifested in the forebay data could be compared to similar periods to suggest the processes <br /> <br /> <br />behind the long and short term trends, there remain questions for this period. The monthly lake- <br /> <br /> <br />wide trips from 1971 to 1982 proved invaluable in discerning the patterns to the processes. This <br /> <br /> <br />period of decreasing resolution identifies the value of the quarterly lake wide sampling for <br /> <br /> <br />determining lake-wide processes that are manifested in the forebay data. <br /> <br />03/06/98 <br /> <br />DRAFT <br /> <br />Page 26 of 62 <br />