Shoshone-Bannock Tribes - Idaho Power

Idaho Power CompanyResponses to CommentsRESPONSE TO COMMENT SBT1-181Studies that IPC has performed with respect to sand beaches in Hells Canyon indicate that whilesandbars have declined in size and number since the HCC was constructed (see Appendix 4,section 6), it is clear that there was erosion in the canyon before the HCC was constructed andthat there are many potential causes for this decline other than the construction of the HCC (seeAppendix 4, section 10). Geotechnical analyses indicate that load following does not increase theerosion of sandbars (see Appendix 4, section 7) but that flood flows (not controlled by IPC) maydestabilize terraces. In addition, a comparison of sediment trapped in Brownlee Reservoir withsamples taken at sandbars in Hells Canyon indicate that the sediments trapped in BrownleeReservoir are generally too small to have contributed to sandbar construction and maintenance.An analysis of aerial photographs (see Appendix 4, section 6) indicates that sand features inHells Canyon do not show a continuing declining trend and that they may be reaching a newequilibrium level, having adjusted for significant changes in sediment supplies over the last200 years or so. Therefore, while the HCC has likely had some effect on sediment features inHells Canyon, it clearly is not responsible for all observed effects and may not be responsible forvery much of the observed change at all.RESPONSE TO COMMENT SBT1-182For the sake of clarity, IPC will change the sentence to read: “The effect of project operationsdownstream is yet to be empirically distinguished from the effects of natural river flows, theaction of ground water, and other phenomena (see Response to Comment USFS3-261).RESPONSE TO COMMENT SBT1-183Comments and IPC responses to comments will be included in the FLA.RESPONSE TO COMMENT SBT1-184The tribes involved in the ethnographic studies include the Burns Paiute Tribe, the ConfederatedTribes of the Warm Springs Reservation, and the Confederated Tribes of the Umatilla IndianReservation. The Shoshone-Bannock Tribes were invited to participate but declined theinvitation.RESPONSE TO COMMENT SBT1-185The tribes involved in the ethnographic studies include the Burns Paiute Tribe, the ConfederatedTribes of the Warm Springs Reservation, and the Confederated Tribes of the Umatilla IndianReservation. The Shoshone-Bannock Tribes were invited to participate but declined theinvitation.RESPONSE TO COMMENT SBT1-186The tribes involved in the oral history studies include the Burns Paiute Tribe, the ConfederatedTribes of the Warm Springs Reservation, and the Confederated Tribes of the Umatilla IndianReservation. The participants were mostly tribal elders from those tribes. TheHells Canyon Complex Page 75