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MEMORANDUM <br />COLORADO WATER CONSERVATION BOARD <br />David W. Walker <br />Director <br />TO: Keith Eberhardt <br />FROM: Dennis Miller <br />DATE: January 3, 1992 <br />SUBJECT: Lake San Cristobal, Proposed Remedial Measures <br />Back round <br />It has been proposed that CWCB Construction Fund resources be expended to <br />perform channel stabilization work in the overflow section from Lake San Cristobal <br />into the Lake Fork of the Gunnison River. The existing overflow section consists of <br />a buried timber crib structure across the bottom of the channel, forming a crest length <br />of 80 feet, enclosed on each end by vertical- walled timber crib structures rising about <br />5 feet above the channel floor. These structures are about 40 years old and in varying <br />states of decay. The channel side wall sections, in particular, are in some danger of <br />collapse during higher flow conditions, an event which might produce flooding <br />downstream as surcharge storage in the lake would be passed through a widened <br />opening. <br />Additionally, a row of boulders 2 to 3 feet in diameter was placed across the channel <br />entrance just upstream of the timber crib structure in the spring of 1990, apparently <br />in an effort to restore the storage lost when portions of the top row of the channel <br />floor timbers were dislodged in 1984. While the boulders have accomplished that, they <br />have the negative effect of reducing freeboard and outlet capacity, as well as creating <br />a scour hole on top of the crib structure during spring runoff conditions. <br />