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rationale for excluding a species.. ~f suitable but unoccupied habitat is present, then potential effects to habitat are evaluated.. Suitable l~abitat is present for Colorado River cutthroat trout CRCT} within both Two Elk Creek as well as the Eagle River, so potential effects to this species are analyzed in detail. Suitable habitat is not found within tl~e project area for bluel~ead, flannelmouth, and mountain suckers, as well as for roundtail chub, but all three may be present in the Colorado River downstream. Dewatering of habitat is given as a primary threat to all three species Rees et al.. 2005a, 2005b~ ~taeek et al. 2005}. However tl~e relatively miniscule amount of water lass, relative to the water yield in the basin, which would be expected as a result of tl~e Tea Cup snowmaking well pr~oj ect, would not have any measurable impacts on these species' habitat in tl~e Colorado River downstrea~n of the prof ect area„ In addition, water quality would not be expected to be affected within the project area or~ downstr~eam~. Therefore, N~ IMPACTS would be expected to flannelmoutl~ sucker, mountain sucker, roundtail chub, or bluehead sucker, as a result of the Vail Mountain Summer Construction projects. Table 3.. Forest Service Sensitive species listed as occurring on tl~e white River National Forest, Suitable Rationale if not Common Name Scientific Name Status Knownlsus ected p habitat carried forward for ,~ to be present. ~ resent. anal sis Colorado River dfzco~^liy~zchus Sensitive Yes Yes Analyzed in detail Cutthroat Trout clar~ki pleuriticus Bluehead sucker Catastorazus Sensitive Na No No suitable habitat discobolus present Flannelmouth Catostornus Sensitive No No No suitable habitat sucker p lati, i~~~iis resent p Mountain sucker Catastomus Sensitive No No No suitable habitat platyr•lzynclius present No suitable habitat Roundtail chub Gira r•obusta Sensitive No No present VI. SENSITISE SPECIES YNE~RMATI~N Co~ora~o ~.lver C~t~~~roat Trout arzcal~livriclius clarki pleur~iticus Colorado River cutthroat trout CRCT} are found only within limited areas across their historic range, mainly within headwater streams or lakes isolated from lower reaches by impassable barriers to upstream ash movement. This isolation, particularly in small areas of watersheds, decreases the probability that native cutthr~aat populations will persist over time previewed in Fausch et al. X006}, A recently completed status assessment for CRCT ~Hir~sch et al. 2006} suggests that CRCT occupy only 1.4% of their former range, while only 8% of its former range is currently occupied with "conservation populations" of CRCT, These conservation populations listed in the CRCT Conservation Assessment and Strategy CRCT Recovery Team 200 ~ }are those that are a naturally reproducing and recruiting populatians with genetic material which is less than 1 a% hybridized with other species or sub-species.. Care conservation populations are assigned to CRCT populations believed to be gr~eater~ than 99% pure. Stacking of nonwnative trout species, historic over-fishing, and impacts to physical stream habitat, such as sedimentation of streams and water withdrawals, have resulted in fragmentation of habitat and the extirpatiota of Colorado River cutthroat trout from much of its former range,.