Targeting Obsolete Dams and Trying to Restore Waterways: Many of the structures block fish migration and hurt river ecology.

In this article, the author talks about how alewives and blueback herring have left the ocean to swim up the Hudson River to any one of scores of tributaries to lay their eggs. Topics include being abandoned by long-shuttered factories and serving no purpose other than to thwart fish migration and harming river ecology; and how major dams were built throughout the West for hydroelectric power, many structures dating to the 1700s and 1800s in the East being built for mechanical power.