A federal study of the economic impact of breaching four dams on the lower Snake River in Washington state overestimated potential negative effects and underestimated the positive, according to a new report by an economist working for environmental groups concerned about salmon restoration. The report found that a draft study by the U.S. Army Corps of Engineers failed to count benefits to Indian tribes and the creation of jobs in commercial fishing and recreation. The draft study also appears to have attributed to possible dam breaching the loss of jobs in industries that are already on the decline in the region, such as seasonal agricultural work. The new study comes out as controversy over possible dam breaching is heating up. Alaska Gov. Tony Knowles (D) recently blamed the dams for helping to kill salmon that the Alaska fishing industry depends on, and enviros have been running full-page ads in the New York Times urging that the dams be breached.