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Implementation Strategy The overall strategy for tlus program is to remove levees from selected floodplain wetlands on a sequential temporal and spatial scale so native fish population response can be carefully evaluated. The design is based on selecting sites over a large spatial scale with the following criteria: I) Geographic location (above and below Desolation/Gray Canyons), 2) High versus low nonnative densities, 3) Depression versus terrace floodplain wetlands, and 4).Natural (sites that naturally inundate during high water years) versus application sites (sites where levees will be removed or breached). These criteria were used to develop a block design selection process for analysis purposes. In addition to these criteria we based the strategy on the following assumptions: 1) Initial efforts would occur in the Green River system, 2) A period of two to three years would be required to evaluate each application activity, and 3) Adjustments to the strategy would occur as warranted based on new information. Specific activities for levee removal in the first year (1996) are identified below. These activities are followed by two additional years (1997-1998) of evaluation. Additional levees for breaching or removal in out years (i 998 and beyond) will be identified after the first full year of evaluation (1997) and analysis ofinforrnation collected during the first two field seasons (i 996 and 1997) is complete. Leve~ Removal Activities Green River The 1996 levee removal block design consists of selection of 10 application sites and iO natural siles, above versus below Desolation/Gray Canyons (Table i). Two treatments will occur within each block. These are nonnative density and floodplain wetland type. Each treatment has two levels: high versus low normative densities and depression versus terrace habitats. Naturally flooded areas will be used to contrast responses in application sites. That is, for each treatment combination of the values observed in the natural sites will used as a simple contrast to application sites. We have identified approximately 30 potential candidate sites to fill in this strategic design plan for levee removal in 1996. These sites are listed in appropriate block (Blocks 2 and 3). The selection of final sites for levee removal or breaching from this list will be based on the following factors: 1) relative flood-ability and drain-ability, 2) landowner willingness to participate, and 3) contaminants. Colorado River Initial efforts will focus on the Green River system, however, future efforts will be directed toward both the Green and Colorado River systems. A potential levee removal block design for the Colorado River system consists of selection of2 application sites and 2 natural sites (Table 1). Two treatments will occur within each block. We have identified 13 potential candidate sites to fill the strategic design plan. These sites are listed in Block 3. s