At dawn, Penobscot Tribal members Butch Phillips, his son Scott Phillips and Scott's daughter, Sage Phillips, paddle a birch bark canoe past Indian Island on the Penobscot River in Maine.
Penobscot River: At dawn, Penobscot Tribal members Butch Phillips, his son Scott Phillips and Scott's daughter, Sage Phillips, paddle a birch bark canoe past Indian Island on the Penobscot River in Maine. © Bridget Besaw


A Great Day for Free-Flowing Streams

Army Corps Announces Support for Dam Removals as Mitigation for Stream Development

Today the U.S. Army Corps of Engineers announced new national guidance that is likely to accelerate the removal of obsolete dams to meet the goals of the Clean Water Act.

Federal requirements to offset impacts of development to streams provide more than $3 billion each year for projects that can improve the health of the nation’s rivers. Historically, the removal of dams and other barriers to free-flowing rivers was not a commonly used option to restore lost stream functions. The guidance issued this week affirms the ecological benefits of removing obsolete dams and provides a new level of clarity that will make it easier and more efficient to do so.

The announcement comes the same day many are celebrating the 50th anniversary of the National Wild and Scenic Rivers Act. The Act was created by Congress to balance the development of dams and other construction on rivers, with a policy for the preservation of certain rivers with “outstanding natural, cultural, and recreational values in free-flowing condition for the enjoyment of present and future generations.”

American waterways bear the effects of more than 100 years of heavy and widespread development. As a result, less than 2 percent of rivers in the U.S. are free-flowing—that is not constrained by dams, levees, culverts and other obstructions.

“Nationally, tens of thousands of dams are considered obsolete and can be hazards to people and nature. This guidance supports an approach to permanently restore river health, while also addressing a long-standing infrastructure problem,” said Tara Moberg, a senior freshwater advisor for The Nature Conservancy. 

“Compared to traditional mitigation, dam removal projects support highly durable outcomes that can permanently increase fish and wildlife habitat by allowing species to move freely up and downstream and by improving river flows and stream temperatures,” Moberg added.

Moberg also pointed out that obsolete dams can pose serious threats to people and property. For instance, flooding in South Carolina in 2015 demonstrated how derelict or unmaintained dams are more likely to fail during floods, as 51 dams breached, exacerbating damages and putting thousands of people at risk. At least a dozen dams were breached as a result of Hurricane Florence last month. Also, since the 1960s, hundreds of people have drowned at small, “low head” dams, many of which are considered obsolete.

“This policy supports market-driven solutions for mitigation, which have been demonstrated to cut permitting times in half,” said Jessica Wilkinson, a senior policy advisor for The Nature Conservancy who specializes in mitigation. “The Nature Conservancy is pleased that the Corps recognizes the benefits that mitigation plays in supporting permitting efficiencies and conservation.”

Wilkinson was the lead author of the report published by the Conservancy in 2017 titled “Environmental Markets and Stream Barrier Removal: An Exploration of Opportunities to Restore Freshwater Connectivity Through Existing Mitigation Programs.” The Army Corps’ new guidance is supported by the recommendations outlined in the report.

The report includes a list of 38 cases where mitigation credits were provided when obsolete dams were removed. One case was the Lowell Mill Dam on the Little River in North Carolina, which was removed in 2005. Subsequent monitoring has shown that the dam’s removal improved water quality, helped the recovery of two endangered mussels, and improved access for migrating American shad, which are important forage species for sportfish like striped bass.

The announcement also comes as a dam in Maine is being removed—in part through funding from mitigation credits—that will restore a saltmarsh at Frenchman Bay near Bangor. The removal will provide critical habitat for smelt, a small fish that is an important source of food for Atlantic salmon and other important species. 

The Nature Conservancy is a global conservation organization dedicated to conserving the lands and waters on which all life depends. Guided by science, we create innovative, on-the-ground solutions to our world's toughest challenges so that nature and people can thrive together. We are tackling climate change, conserving lands, waters and oceans at an unprecedented scale, providing food and water sustainably and helping make cities more sustainable. Working in 79 countries and territories, we use a collaborative approach that engages local communities, governments, the private sector, and other partners. To learn more, visit or follow @nature_press on Twitter.