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Irrigation Sector Economic Impacts on the Lower Snake River Benchmark Review for Dam Breaching and Mitigation Costs Executive Summary-March 2024
This benchmark review is already dated as it is being written , as it reaches into an unknown future , where decisions affecting dam breaching on the Lower Snake River ( LSR ) are far from being certain--particularly as they impact mainstem irrigation projects along Ice Harbor and Upper McNary pools .
The LSR EIS litigation settlement agreement , approved by the Plaintiffs and Defendants , defers significant physical changes to the LSR hydro projects by at least five to ten years . In real-world terms , decisions would have to be determined and reconstruction measures executed today , for irrigation systems to be operational by 2030 .
Nevertheless , the economic impacts can be placed in today ’ s context for executive and legislative considerations . Irrigation Impact Area :
• This review designates a well-specified impact area , taking into account the full effect of dam breaching and pool drawdowns on the LSR and Columbia River system . The primary impact area covers about 92,500 acres served by the Ice Harbor-LSR River and Upper McNary-Columbia River Pools .
Irrigation Pump Station Modifications :
• The breaching of Ice Harbor Dam would lower the water surface elevations making all of the existing irrigation pump stations located in the pool inoperable ; and changes to river topography and huge volumes of siltation would affect pumping stations below the existing Ice Harbor Dam tailrace to the confluence of the Walla Walla River and McNary Pool .
• Direct reconstruction costs are considered to be water pumping infrastructure costs associated with significant modifications or replacement of irrigation pump platforms and / or pumps , intakes and screens entering the river , manifolds from the pumps to the mainline piping systems , associated electrical connections , all excavation works , and drilling replacement wells .
o The direct station-by-station reconstruction costs are estimated to be between $ 92-184 million
( 2021 $). Future costs are expected to escalate significantly . o A main pipeline configuration is estimated to cost at least $ 500 million to $ 1 billion . o Reconstruction timelines from design to operations are estimated to be about 2-5 years . o Minimal disruption to irrigation water service is estimated to be about 1-2 years ( unavoidable ).
Risk Mitigation Cost Estimates :
• The risk mitigation assessment methodology accepts that national economic development ( NED ) impacts would manifest as “ distressed ” land values under dam breaching conditions . This value impact would be about $ 578 to $ 759 million .
o $ 578 to $ 759 million required mitigation payments to land-irrigation project owners . o Estimated shared debt ( financing ) obligations by Bonneville Power Administration and Washington
State would be about $ 35 to $ 47 million , annually .
Regional Household Income Impact Estimates :
• The potential regional economic development ( RED ) impacts are estimated as annual value of household income tied to the affected irrigation area , defined as the Irrigated Agriculture Industry , with direct , indirect , and induced impacts to regional income .
o Total regional income values ( impacts ) are estimated to range between $ 450 to $ 464 million . o It would be impossible to mitigate fully regional income impacts , if LSR dam breaching occurred .
Columbia- , March 2024