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Arizona Game and Fish Department Biological Evaluation: Kanab Ambersnail July 1998 Page 2 meadows may provide crucial vegetative cover and food resources for the snails (Clarke 1991). This site experienced some habitat loss in 1990-91 from wetland destruction and livestock trampling, and in 1994 from floods. The 3L population may experience further habitat loss and an uncertain fate as the landowner plans to commercially develop the area (USFWS 1995). In 1991, a third population was identified at Vaseys Paradise (VP), the site of a large, perennial spring in Grand Canyon National Park (Blinn et al. 1992; Spamer and Bogan 1993). This site is located along the Colorado River at 31.8 mi river right (51.2 km downstream of Lee's Ferry, Coconino County), and is relatively secure from impacts by livestock and commercial development (Spamer and Bogan 1993). Kanab ambersnail habitat at VP is characterized by dense patches of cardinal monkeyflower (~mulus cardinalis), watercress (Nasturtium officinale), water sedge (Carex aquatilis), and smartweed (Polygonum amphibium) . Lush riparian vegetation and spring water make VP a popular site for river runners and hikers in Grand Canyon. Recreational impacts to KASs and their habitat at VP are limited by dense poison ivy (Toxicodendron rydbergii) patches which discourage most intrusion into vegetated areas. High releases from Glen Canyon Dam (75.3 km upstream of VP) may pose a greater threat to the VP site by inundating, degrading, and scouring KAS habitat (Spamer and Bogan 1995; USFWS 1995; Stevens et al. 1997a, 1997b). The VP population experienced habitat loss (ca. 16% of total habitat) and incidental take during an experimental 45,000 cfs (1275 m3/s) stage flow in March 1996 (Stevens et al. 1997a). The extant Arizona and Utah KAS populations are geographically isolated (92.9 km distant) and occur in different watersheds. Both populations are believed to be relict from the last glaciation (Late Pleistocene Epoch) when the regional climate supported more wetland habitat (Spamer 1993, Spamer and Bogan 1993, Stevens et al. 1997b). The fossil record of Oxyloma is represented only by shells collected in Late Pleistocene deposits of the San Pedro Valley, Arizona (Bequaert and Miller 1973) and in 9,200 year-old sediments near Lake Powell in southeastern Utah (Kerns 1993). Desertification of the American Southwest over the last 10,000 years has reduced the number and size of available habitats that could have sustained KAS populations. However, the presence of Glen Canyon Dam, and the consequent absence of pre-dam floods, have allowed the vegetation at VP to expand.