2020 Lower Snake River Dam Breach Mitigation Plan and Cost

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Our Mitigation Plan 2020 report shows dam breaching plus mitigation can be done for approximately $500-750 million.

This report outlines various mitigation features that will or could be required upon breaching the four lower Snake River dams (LSRDs). Mitigation is based on the assumption that all four dams are breached by removing their earthen berms and, with two of the dams, part of the earthen abutment to the berms.

This is the well-developed plan put forth by the Corps of Engineers in the 2002 LSRD Feasibility Study and EIS (02 EIS) to improve juvenile salmon passage over the 4LSRDs. The 02 EIS laid out various mitigation measures and costs. Additional mitigation found to be appropriate was identified by a small group of Corps retirees and volunteers who in 2016 developed a Reevaluation (REval) of the 02 EIS Breach Plan (Appendix D Natural River Drawdown Engineering). The report included added and corrected mitigation costs.

As you will see in the report, the team here further corrected/updated the plan and costs for mitigation in 2020. Note that the 2020 EIS for the Columbia River System did not utilize the updated information in these reports. Instead, the 2020 EIS took the original breach cost in the 02 EIS and converted it to 2020 dollars, which increased the overall cost of the breach alternative, (identified in the 2020 EIS as Multiple Objective 3). This perpetuates faulty assumptions and unnecessary cost.

Corrected breach costs plus predicted mitigation costs intended to keep everyone whole, were found to be much less than the overall costs stated in the 02 EIS, and thus the 2020 EIS estimate. Further savings can be anticipated, and $500 million is an approximate price tag that will vary based on agency decision making and field conditions.