How Dams Affect Salmon Migration

The 1,000 plus species of Salmon and Steelhead that live off the western coast of the United States and breed in the rivers and tributaries of California, Washington, and Oregon have greatly fallen in population. 106 species have become extinct and 314 more are at risk of extinction in the Columbia River Basin, the focus of this report. The causes of this are dams on the rivers stopping salmon from breeding and smolt from returning to the ocean, …

…Enhancement measures seem to be having little effect. In some cases, enhancement measures are actually harming the fish. Drawdown is, to me, the only practical and effective way of allowing juvenile salmon down the rivers, while also virtually unaffecting power supplies, agriculture, or other human requirements of the rivers. Also, drawdown will only occur when smolt are migrating downstream, since adult salmon don't need it going upriver and nearly all of them die after spawning.