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<br />KAS occurs on cattail (~ sp.) at Three Lakes, near Kanab, Utah, and <br />cattail is the dominant macrophyte at that locality. In contrast, Vaseys <br />Paradise is a fast-flowing, cool, dolomiticwtype spring, with abundant wetland <br />and phreatophyte vegetation, including native crimson monkey-flower, poison <br />ivy and non-native water-cress. Crimson monkey-flower and non-native water- <br />cress are perennial aquatic wetland or hydrophytes (Kearney and Peebles 1960), <br />and KAS was almost completely restricted to those two species along the edges <br />of the Vaseys Paradise stream (Stevens et al., 1995). KAS was rare to absent <br />on other plant species and substrata in 1995. Introduction of water-cress <br />provided KAS with an alternate host plant, and completion of Glen Canyon Dam <br />increased overall primary habitat area at Vaseys Paradise by approximately <br />40"'. <br /> <br />Demographic analyses based on size class distribution indicated that KAS is <br />essentially an annual species, with much of the population maturing and <br />reproducing in mid-summer (July and August), and most snails over-wintering as <br />small size classes (Stevens et al., 1995). Loose, gelatinous egg masses were <br />observed on the undersides of moist to wet live stems, on the roots of water- <br />cress, and on dead or decadent stems of crimson monkey-flower in August, 1995. <br />No data on egg development or emergence success are available. <br /> <br />KAS at vaseys Paradise were parasitized by a trematode, tentatively identified <br />as Leucochloridium sp., with 8.3 to 9.5'" of the mature snails expressing <br />sporocysts in August, 1995 (Stevens et al., 1995). Potential vertebrate <br />predators of KAS at Vaseys Paradise include rainbow trout (oncorhvnchus <br />mvkiss) in the stream mouth, summer breeding Says and black phoebe (Savornis <br />~ and a. niari~anR), canyon wren (Catheroes mexicanus), and winter resident <br />American dipper (CincluR mexicanus) . <br /> <br />Impacts of the test flow <br /> <br />In a December 21, 1994, Final Biological Opinion (BO) the Service evaluated <br />impacts to KAS from the operation of Glen Canyon Dam according to operating <br />and other criteria of the MLFF contained in the GCD-EIS. They determined <br />implementation of the MLFF would not jeopardize the continued existence of the <br />KAS. This opinion also supported the concept of a beach/habitat building flow <br />of 40,000 to 45,000 cfs, which is part of MLFF. However, the opinion c~early <br />articulates that incidental take of KAS will be exceeded if more than 10'" of <br />the occupied habitat in Grand Canyon will be inundated by high flows or a <br />controlled flood. Considering the Service previously determined the MLFF <br />(including the beach/habitat-building flow) would not jeopardize the KAS, this <br />assessment examines the probability of exceeding the incidental take level <br />during the test flow. <br /> <br />Introduction of non-native water-cress and construction and operation of Glen <br />Canyon Dam increased the primary KAS habitat area by more than 40"', and <br />resulted in an increase in the snail population. The KAS population at Vaseys <br />Paradise survived and recovered from innumerable similar and higher flows <br />during the pre-dam era, and has survived six flows in excess of 45,000 cfs <br />during the post-dam era (i.e., 1965, 1980, and 1983-1986). Short-term <br />reduction in primary habitat area by scouring flows does not appear to affect <br /> <br />5 <br />