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' CHAPTER III AFFECTED ENVIRONMENT G. Candidate Species r A number of species that are being considered for listing status (candidate species) occur within the Upper Basin. Most of these species are associated with upland habitat and therefore would not be affected by the alternatives considered here. The exceptions are: The southwestern otter (Lutra canadensis sonorae) is primarily associated with the Lower Colorado River Basin. Southern Utah apparently represented the northern limit of its range. There appear to be no recent records of this subspecies within the Upper Basin. The long-billed curlew (Numenius americanus) utilizes open grazing lands, cultivated fields and irrigated pastures. The limiting factor for this species appears to be the loss of short-grass prairie. The western snowy plover (Charadrius alexandrinus nivosus) is primarily associated with wetlands, alkali ponds, and riverine sandflats. In Colorado, populations apparently occurred in the San Luis Valley, on the South Platte, Republican, and Arikaree Rivers. Extant populations may remain along the ' Arkansas River west of the Kansas border. There is no current information of its occurrence in Utah, although it is considered a possible summer resident and spring/fall migrant. The western yellow-billed cuckoo (Coccyzus americanus occidentalis) is associated with deciduous woodland habitat along riparian corridors; however, there have been only sporadic reports of the subspecies in Colorado and Utah. 1 Two breeding areas are known from eastern Utah, but no birds have been seen in these areas in over 6 years. It is not known whether the subspecies currently occurs in Colorado. A member of the orchid family, the plant Spiranthes diluvialis exhibits a discontinuous distribution. Populations are limited to relatively low elevations in mesic or wet meadows along permanent streams and around springs ' and major desert lakes. These sites are commonly subject to intermittent and unpredictable inundation and the plants often emerge from shallow water. The species has been collected from only about 10 sites. Three occur within the ' Upper Basin; however, two of these are located along small tributaries which eventually drain into Lake Powell near the most downstream portions of the Upper Basin. A third population is known to occur in Daggett County in the Browns Park area. It is associated with moist alluvial meadows adjacent to the Green River. The Colorado River cutthroat trout (Salmo clarki pleuriticus) is found within the Upper Basin drainage, but is currently limited to a few small headwater streams and lakes in northwestern Colorado and southwestern Wyoming. In 1981, approximately seven streams and a lake in Wyoming contained pure populations (Hickman and Benton 1981). In Colorado, approximately six streams and two lakes are believed to maintain pure populations. Most of these populations are located in headwater streams. III-23