by Kevin Schofield
This weekend’s read is a draft report from the State of Washington on the future of four controversial dams on the lower Snake River in eastern Washington. The dams are co-managed by the Army Corps of Engineers and the Bonneville Power Administration, which harvests hydroelectric power generating facilities there. Together the four dams generate about one gigawatt of electricity, up to three gigawatts at peak times.
But the impact of the dams goes far beyond the power generation: they have dramatically changed the Snake River ecosystem over the last fifty years. Behind each dam sits a large reservoir, and collectively they have shifted the river from an active, running one to a “still”, slow-flowing one. That makes a large difference, particularly for salmon swimming out to the ocean and back upstream to spawn: between the dams (which have fish ladders) and the reservoirs, it changes the flow and difficulty for salmon to navigate the river, and it creates easy opportunities for predators who feed on salmon to catch them in the waters behind the dams. There is substantial evidence that the Snake River dams have created barriers to native salmon and have contributed to reductions in salmon populations to the point where many are now at or below the “quasi-extinction threshold;”; they are not expected to survive in the long-term without intervention. The dams have had similar effects on steelhead and lamprey populations.Continue reading Weekend Reads: The Snake River Dams