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~ 1 Y VI. Recommendations Several important issues would have to be resolved to complete a wetlands connection to the river channel. Resolution of these issues may require: • An evaluation of the potential impact of the high selenium concentrations on the wetlands biology. • An analysis to determine if the high selenium concentration can be mitigated by dilution or removal with a inflow channel to the wetlands. • Selection of a preferred wetlands water surface elevation. • An analysis of sediment load in this reach of river and potential impacts of sediment deposition on the wetlands biology. An estimate of the long term potential sediment deposition in the wetlands for the proposed hydraulic design is suggested. Recommendations are presented for additional data collection that would assist in the assessment of the proposed hydraulic design. A. Future Cross Section Surveys. Annual cross section surveys in this reach will not be required fox the purpose of predicting water surface elevations unless future extremely high discharges and substantial changes in channel geometry or slope occur. The cross section geometry changes related to sand storage or scour at certain cross sections have been dramatic but do not significantly influence the prediction of water surface elevation. Future cross section surveys should be based on a specific objectives: • To determine if the cobble substrate at the spawning bar has been scoured of sand prior to the spring runoff. • To examine the inundation of the cobble substrate at the spawning bar area during the peak flows of future low, moderate or high flow years. • To conduct an investigation of channel changes after very high flow years. • To obtain further detail of the river channel around the wetlands inlet and return flow channels for design requirements. • To document any long term channel incision. 37