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SOlentlfle FvQhmtlon of A101091¢al Opinions on Pnriangon:d and Thrmtoned T orq in the Klamnth RiverBmin: interim Report (2002) <br />hQjc�R�b+ nup. aWh +f,cnl,�ntln7,r�{pIr7Q,uN,nV1Z efml. cnlrynFhl OMq. 2 M,l '1110 National nC:IACRM' nY;kknc:x all Aphv ImLmed <br />ENDAN6EREb AND DMATENED IMES IN TMJKLA)MAMBIVER BASIN <br />The span of lake level records that the USBR chose to use in its analysis (1960- <br />1998) reflects the full interval of operations for the completed Klamath Project. Even <br />earlier records are available, extending back to the creation of Link River Dam in 1919 <br />(Figure 3), but the interval between 1919 and 1960 would not be typical from the <br />viewpoint of current proj cct operations. Records prior to 1919, extending back to 1905, <br />also are available (Figure 3); they show higher maximum and minimum lake levels than <br />have been typical of Upper Klamath Lake since closure of the dam. In addition, <br />operation of the Klamath Project has created a higher amplitude of int uannual variation <br />in lake level and a change in seasonality of intmannual change in lake level as compared <br />with the original condition of the lake (USFWS 2001, 111. 2., page 38). <br />4143 <br />4142 <br />4141 <br />d <br />d <br />4140 <br />4139 <br />3 <br />4138 <br />4137 <br />4136 <br />1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 <br />wafer year <br />Figure 3. Historical record of level at the end of September for Upper Klamath Lake <br />(from USBR sources). <br />k While the operating interval between 1960 and 1998 is very useful for judging the <br />degree of variability that can be expected in lake levels over a long period of years with <br />the Klamath Project in place, the possibility for use of lake -level data in environmental <br />analysis is limited to a much shorter interval. Interaction between lake level and <br />environmental variables or indicators of the welfare of the endangered fish is dependent <br />on concurrent information for lake level, environmental conditions, and fish. While <br />information of a sporadic or anecdotal nature is available over as much as 100 years, <br />routinely - collected data on environmental characteristics and fish are available only since <br />1990 or later. Thus, while the long -term lake level record seems to invite statistical <br />analysis of the welfare of fish in relation to lake level, the information at hand is actually <br />limited to a period of ten years or less. This limitation explains the focus of this report <br />and of the USFWS biological opinion on data extending over approximately the last ten <br />years. All three lake -level regimes (USFWS KPA, USBR recommended, historical) <br />12 <br />966 -d BEOMO 'd 96Z -1 899699SE08 s3odnosu 1vNnIVN 104 -1NMi zv :[[ ZOOZ- 80 -93d <br />