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'~,\ ,,'" -f~ f;,l ''''~ (Table 2). For example, figures in Table I indicate that approximately 105.5 m' of primary habitat would be lost if the 1275 cms flood had occurred during September 1995. The model may have overestimated the actual 1275 cms line. If the actual line is 0.5 m below the estimated line, only 83.9 m2, or 9.4 percent of the habitat would have been lost. Similarly if the model is incorrect and has underestimated the 1275 cms line, instead of the loss of 105.5 m', approximately 128.9 m2 or 14.4 percent of the habitat would have been lost. For March, the 1275 cms line will result in the loss of 125.1 m2. If the model is incorrect and the actual 1275 cms line is 1.5 feet below the estimated line, only 108.1 m2, or 12.7 percent of the habitat would have been lost. Similarly, if the model is incorrect and has underestimated the 1275 cms line, instead of the loss of 125.1 m2, approximately 143.8 m2 or 16.9 percent of the habitat would have been lost (Table 2). ;1 (~ f , , Assuming the modeled 1275 ems line is correct and 105.5 m2 of primary habitat will be lost, we estimate that an additional 1 foot of habitat (15.39 m2) will be impacted by the high flows. This 15.39 m2 plus the 105.5 m2 equals 120.89 m' of habitat or 13.5 percent of the total. This upper one foot of habitat is likely to be saturated. drenched. and or otherwise permeated but is not expected to be totally lost. Some of the individuals snails found in this area may find refuge and might be expected to survive. Similarly in March. 1 foot of habitat (12.34) above the estimated 1275 cms line means the total amount of habitat affected by the flood would be 117.8: m2 or 15.31 percent. " '" q ~~ ~~ ,. '" " :-'.. ,:,;, In addition to the loss of habitat, the proposed project will result in the loss of individual Kanab ambersnails. Individual Kanab ambersnails are expected to be displaced from the habitat';and drowned. Individual ambersnails that are in the zone of inundation that are not salvaged will be lost. If a test flow of 1275 cms had occurred in March of 1995, some 617 individuals. approximately 3.3 percent of the individual Kanab ambersnails at Vaseys would have been lost. However, the figure could be 11.4 in June or as high as 18.7 based on September figures. Information on population estimates are seasonally variable (Table 1). f 6 t. j'f The total population estimate during March 1995 was approximately 18,600 individuals. In June of that same year, the total estimated population had increased to 20,024 individuals with 2,275 or 11.4 percent of the individuals below the 1275 cms line. By September 17,370 or 16.7 percent of the estimated 104,004 individual Kanab ambersnails inhabited the area below 1275 cms. Alternative population estimates for September put the total population at 92,764 or 18.7 percent of the population below 1275 cms. 1r;,- , ".)';. ~I:~ ~, J~; I How long the Kanab ambersnail can be inundated is not known. Individuals may possibly withstand short periods of inundation or be able to emerge if refuge exists. Up-ramp rates toward the peak of 1275 cms are scheduled to raise at a rate of 113 cms per hour. Estimates for the maximum 2Q-minute stage change at Lees Ferry for the modified low fluctuating now alternative is estimated at 0.03 m (U.S. Bureau of Reclamation 1995b). Nevertheless, whether the individuals will have the opportunity or ability to crawl out of harms way is not known. Individuals that merely climb up a piece of vegetation will be expected to perish since the high flows will last for 7 days. """ I Biological aod Conference Opinions Glen Canyon Beach/Habllal.Building Flows 2116196 19