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<br />O"''''3~ 6 <br />tiC 1. <br /> <br /> 1985 18.21 4 19.09 0% 1 MAF, 5% 3700.1 <br /> 1986 18.40 3 16,85 0% 0,9 MAF, 6% 3700.0 <br /> 1987 14.23 10 13.43 0% 0% 3698.5 <br /> 1996 11.28 19 11.47 0% 0.2 MAF, 2% 3688.3 <br />. 1997- 44.62+ -6 .12.10+ 0% 0% 3695.1 ' <br /> <br />Dissolved oxygen values become very unstable at this time due to faulty and erratIc <br /> <br />instrument readings. Some of the more reasonable values and patterns suggest a high degree of <br /> <br />oxygenation of the hypolimnion accompanied by modest metalimnetic dissolved oxygen sags <br /> <br />following the spring flood. Under more typical release patterns we would expect a major flood <br /> <br />event that follows drought conditions to introduce a large quantity of organic carbon creating that <br /> <br />would create a high biological oxygen demand (BOD). While there are repeated episodes of <br /> <br />metalirnnetic hypoxia throughout the 1980's, they are not severe, nor do they translate to <br /> <br />subsequent hypoxia in the hypolimnion. Spillway withdrawals have intercepted part of the spring <br /> <br />flood along with the high organic concentrations it entails. This effect could be real or it could be <br /> <br />an artifact of poor data quality and low temporal resolution, but epilirnnetic releases in the 1960' s <br /> <br />produced similar patterns. Dissolved oxygen values present more questions than they answer, <br /> <br />which may be addressed if the current scenario of continued high anticipated flows is manifested. <br /> <br />The reservoir conditions preceding the 1984 flood are significantly fresher than the previous <br /> <br />year. A very cold winter and low chemical gradient created a good opportunity for a thorough <br /> <br />underflow winter current. This process may have been initially augmented by high river outlet <br /> <br />withdrawals (running above recommended capacity for 2\1, months) and eventually discharges <br /> <br />out-competed the underflow currents, entraining much of the convectively mixed epilimnion. <br /> <br />Although monitoring resolution was inadequate to capture the exact process of flow, another <br /> <br />equi-potential flow-through appears to have eliminated any significant trace of a hypolimnion. <br /> <br />03/06/98 <br /> <br />DRAFT <br /> <br />Page 40 of 62 <br />