A Congressional study has found that the US Army Corps of Engineers (USACE) may have underestimated the impact on air quality in the northwest US if four dams on the Snake river are breached to restore salmon runs, and the electricity they generate replaced by power from coal or natural gas fired power stations. The General Accounting Office (GAO), the US Congress’ bipartisan investigative arm, also suggested that USACE may have underestimated the cost of replacing the transportation system of barges with trucks and trains to carry grain downstream.

The study was requested by two Republican senators, Slade Gorton of Washington and Gordon Smith of Oregon. However, they believe that USACE’s estimate of US$245M to replace the electricity from the dams if they are breached is correct.

USACE released an environmental impact study on dam breaching in December 1999 which looked at the possibility of breaching four dams: Ice Harbor, Lower Monumental, Little Goose and Lower Granite. The study also examined other alternatives to rebuild the salmon population, but it did not decide whether dam breaching was the best way to proceed.

GAO believes that air quality could also be affected by pollutants from trucks which would replace the barging system.