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238 atures (Martinez unpublished data). Unless stocked, channel catfish should not increase in abundance in Kenney Reservoir or in the White River above the reservoir. Green sunfish were considered rare in the White River and restricted largely to Utah (Tyus et al. 1982). Adult and young-of-year green sunfish were collected below the dam in 1989-1990 suggesting this species could spread throughout in the lower White River. Conditions in Kenney Reservoir proved favorable for black crappie; this species re- produced successfully in the reservoir and may re- produce in the river immediately below the dam (Trammell 1991). Reports of black crappie in the White and Green rivers near their confluence in Utah in 1989 (S. Cranney personal communication) confirmed that its distribution increased greatly be- yond that reported by Tyus et al. (1982). Other warmwater sport fish collected, black bullhead, blueg,ill and largemouth bass, are not expected to increase dramatically, but the reservoir provides more favorable habitat for them than occurred in the unimpounded White River. Large numbers of trout stocked in Kenney Res- ervoir moved over the dam resulting in as many trout being harvested in the plunge pool and chan- nels immediately below the dam as in the reservoir itself. While trout were reported in the White River as much as 50 km below the dam. few were reported after springtime suggesting that trout moving downstream out of the reservoir were caught, had dispersed widely, or had died. Trout escapement from the reservoir was presumed innocuous, how- ever. large numbers of trout in the river increased angling activity that may have increased incidental catch of Colorado squawfish. Construction of large main stem dams on the up- per Colorado River and its tributaries have contrib- uted to highly altered flow, water temperature, and sediment transport at the expense of native fishes (Wydoski & Hammill 1991). Aside from the result- ing loss of stream habitat through inundation and blockage of migration routes due to impoundment (Wydoski & Hammil 1991), Taylor Draw Dam and Kenney Reservoir imparted comparatively subtle physical changes to the White River (Wullschleger 1990. Chart & Bergersen 1992). Despite this, our in- vestigation indicates smaller-scale, main stem im- poundments pose a substantial threat to native ich- thyofauna by facilitating establishment and prolif- eration of non-native fishes. Probably the greatest boon to non-native species resulting from Kenney Reservoir is that it provides suitable habitat for their recruitment. It is this ecological benefit to non-native species that will facilitate their contin- ued proliferation in the White River. Acknowledgements Water User's Association Number 1 provided fund- ing for the early portion of this study and their per- sonnel, G. Trainor. J. Geyler and J. 'Hoot' Gibson, provided valuable support. W. Burkhard and R. VanBuren, Colorado Division of Wildlife, initiated this study. A. Martinez identified fish larvae during the early portion of this study. U.S. Fish and Wildlife Service, Colorado River Fishery Project, provided funding. equipment, and assistance in various as- pects of these projects. We especially thank USFWS biologists L. Kaeding. B. Burdick and H. Tyus. S. Cranney. Utah Division of Wildlife Re- sources, provided fish distribution and access infor- mation during the early portion of this project. We thank W. Wiltzius. T. Powell. T. Nesler, R. Behnke and an anonymous reviewer for reviewing drafts of this paper. References cited Baxter, G.T. & J.R. Simon. 1970. Wyoming fishes. Wyoming Game and Fish Department Bulletin 4. Cheyenne. 168 pp. Chart, T.E. 1987. The initial effect of impoundment on the fish community of the White River, Colorado. M. Sc. Thesis. Col- orado State University. Fort Collins. 112 pp. Chart, T.E. & E.P. Bergersen. 1992. Impact of mainstream im- poundment on the distribution and movements of the resident flannelmouth sucker (Catostomidae: Catostomus latipinnis) population in the White River, Colorado. Southw. Nat. 37: 9- 15. Hickman. T.J. 1983. Effects of habitat alteration by energy re- source developments in the Upper Colorado River Basin on endangered fishes. pp. 537-550. /n: V.D. Adams & V.A. La- marra (ed.) Aquatic Resources Management of the Colorado River Ecosystem. Ann Arbor Science Publishers, Ann Arbor.