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f The fourth option would destroy by electrocution all species, sizes, and life stages (including eggs and larvae) that have bypassed the HPP. The electric barrier would be installed somewhere in the discharge pipe. Experience dictates that it would require approximately 500 microwatts/cm3 to assure destruction of all life forms. Total electric power required is calculated based on the distance over which the power would need to be applied given the 3,000 cfs design flow. For this application, the total power needed would be approximately 13 M Electrocuted fish would wash down the canal with debris and would be allowed to decompose in the canal system. There were no costs estimated for this option. The final option is a combination of a fish screen facility and an electric barrier. This option would save the larger life forms from destruction but would destroy all life forms that bypass HPP. A larger screen opening would be used to exclude large fish from entrainment. The screen could be installed in the intake channel or on the trashracks. No fish bypass would be necessary. Several other options were studied, but not recommended for consideration. These included barrier nets, underwater sound and/or lights, hanging chains, induced gas bubble disease in the Buckskin Tunnel, predator enhancement in the first reach of the Hayden-Rhodes Aqueduct, and placing fish screens/barriers in the aqueduct at an alternate location. The two alternatives, of the five that were considered, that could possibly exclude all life stages from the CAP, was the electric barrier placed in the discharge pipe, or the combination of the electric barrier and the placement of a screen upstream of HPP. 1.4 Conclusion It can be concluded from the two preceding example projects which have close control over water flow rates that species separation with 100 percent certainty is not possible and that even at the very high rates of exclusion achieved, the costs involved are prohibitive. This is demonstrated by the fact that neither of these very restrictive fish passage limitation projects have been implemented. The feasibility of restructuring downstream passage within a natural drainage basin where flow rates are not easily controlled and where a natural connection exists or existed, is even less achievable. This project has several features which make the selection of feasible control options unique. The current technology includes both physical and behavioral techniques to control fish passage. In this case, the behavioral techniques will not stop the passive life stages that may be present and are only marginally effective on controlling active life stages. For these reasons, behavioral techniques were not considered feasible control options at either Elkhead or Highline reservoirs. Physical control devices include several types of screening devices. Since the objective of this study is to control escapement, the best location for controlling the fish is within the reservoir. Any device placed downstream of the reservoir would require construction of a stream channel and physical screening facility large enough to protect to the maximum flow event. Further, the facility would need to be designed to function at the current industry standard for the full range of flows. The wide range of flows from flood flows to near zero would be very difficult to protect with one facility. This may require one facility designed to work at high flows and another to work at the low flows. Further, any fish that get to the downstream facility are already moving toward habitat occupied by r the endangered fish species. Any facility downstream of the reservoirs also would require a fish Control Structure Feasibility Evaluation 1-33 Miller Ecological Consultants, Inc., February 18, 1997