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The concepts of the river continuum (Vannote et al. 1980) and flood pulse (Junk et al. 1989) apply to the Upper Colorado River Basin. The river continuum concept applies to the headwaters and high gradient, restricted meander canyon reaches whereas the flood pulse concept applies to low gradient, unrestricted reaches that form floodplains in the broad valley reaches. Lotic systems not only transfer organic matter from upstream reaches in arid or semi-arid regions (i. e., continuum concept) but also deposit this material in floodplains where high productivity of invertebrates periodically enters the river (i. e., flood pulse concept). Shallow floodplain habitats become much warmer than the adjacent river, increasing the productivity for phytoplankton and development of a food web (Welcomme 1979). Slow growth and higher mortality of endangered Colorado River fishes has been attributed to lower water temperatures in the Upper Colorado River Basin (Kaeding and Osmundson 1988). Floods and floodplains are now understood to be essential components of river systems (Bayley 1991; Petts and Maddock 1994; Sedell et al. 1989). The energy dynamics of large rivers is strongly influenced by floodplain habitats (Sedell et al. 1989) where productivity is higher than habitats in river channels (Hynes 1970; Welcomme 1985; Welcomme 1989). The spawning strategies of fishes in many tropical and some temperate areas are correlated with the flood pulse that is associated with high productivity in shallow, flooded areas where organic matter is retained (Junk et al. 1989). Welcomme (1985) stated that the shallow littoral zone of floodplain habitats produce higher densities of zooplankton when compared with the entire floodplain area. STRATEGIES TO ENHANCE OR RESTORE FLOODED BOTTOMLAND HABITATS IN THE UPPER COLORADO RIVER BASIN The use of floodplains for agriculture, housing, and industrial use has increased in demand and these uses have increased river pollution (Welcomme 1985). Fish assemblages in large rivers vary considerably and are often related to the connectivity of the floodplain with the main channel (Copp 1989). Many riverine fish species exhibit seasonal movements into inundated floodplain habitats for spawning, rearing, and foraging (Finger and Stewart 1987; Lambou 1963; Ross and Baker 1983). Seasonal flooding of bottomlands are important in sustaining various fish species that are characteristic of river channels (Baker and Killgore 1994). Baker and Killgore emphasize that the pattern of flooding appears to be of paramount importance in structuring wetland fish communities and that fish may spread over large areas of the floodplain during high streamflows. The lateral movement of fish on the floodplain decreases exponentially with reductions in streamflow (Kwak 1988) and recruitment may not occur if water levels remain low (Starrett 1951). During low streamflows, backwater habitats become important in sustaining fish populations. Some fish species have modified their behavior to use backwaters and secondary channels of large rivers as substitutes for floodplain habitats as nurseries (Welcomme 1985). Species that cannot adapt to the riverine environment when floodplain habitats are no longer available will perish. The restoration of large floodplain rivers will require at least partial recovery of the natural hydrograph based on the current knowledge of such systems (Bayley 1991; Hesse 1995; Ward and Stanford 1995). But, because of other demands on the use of Colorado River water, extensive flooding of bottomland habitats 22