I sense a renewed interest in salmon and the four Lower Snake River dams.
Here are but two, of many readily available, published references that provide historic insight on salmon numbers:
1. Chapman, D.W. (1986). "Salmon and Steelhead Abundance in the Columbia River in the Nineteenth Century." Transactions of the American Fisheries Society, 115:662-670.
2. McDonald, Marshall (1894). Report of the United States Commissioner of Fish and fisheries on investigations in the Columbia River Basin in Regard to the Salmon fisheries, Government Printing Office, Washington D.C.
Chapman's article contains an interesting graph of "Salmon Catch (Harvest) vs time (from about 1870 to 1970) as well as a listing of numerous other interesting references related to salmon.
Marshall McDonald's 1894 report states that "the investigations made by Professor Evermann and the parties under his direction establish conclusively the fact that there has been a very great reduction in the number of salmon frequenting the head waters of the Columbia River and its tributaries. This decrease is more notable in the main river."
McDonald's 1894 report also states that "they were abundant in the Columbia River at Kettle Falls as late as 1878. Since then there has been a great decrease. They have been scarce since 1882. Since 1890 there have been scarcely any at Kettle Falls."
This 1894 report also states that "there is no reason to doubt -- indeed the fact is beyond question -- that the number of salmon now reaching the head waters of streams in the Columbia River Basin is insignificant in comparison with the number which some years ago annually visited and spawned in these waters. It is further apparent that this decrease is not to be attributed either to the contraction of the area accessible to them or to changed conditions in the waters which would deter the salmon from entering them."
I believe one pertinent question to ask is this:
How will the removal of dams solve a problem (that of declining fisheries) that was noted decades before their construction?
To give some perspective, the problem was noted prior to 1900 and the first Lower Snake River project was completed in the early 1960s, more than 60 years later.