In the last few years, I’ve written periodically about the impact of hydrologic dams on rivers and ecosystems. Most recently I put together a piece for Oregon’s Agricultural Progress magazine about the removal of small dams on Calapooia River in Oregon’s Willamette Valley. An excerpt from the piece is below, to view the whole article, visit: The Long Memory of Small Dams.

The Brownsville Dam was soon joined by two more dams—Sodom and Shearer—built to divert water to a local grain mill. The dams became part of the region’s landscape where they helped develop commerce and community.

However, as the reality of a competitive world market set in, the mills eventually closed. The dams became maintenance liabilities, as well as barriers to fish passage and factors in the ongoing degradation of the river channel. The impact of the dams on water flow was so severe and the diversions so effective that the main channel of the Calapooia River was at risk of running dry. Something needed to be done.

Although the details of these three dams were specific to the Calapooia, the general problem of aging and failing dams was becoming a much larger issue. Across the United States, more than 2.5 million dams obstruct waterways. They range from small structures a few feet tall designed primarily for irrigation to 600-foot structures capable of powering cities. …