Letting A River Run

An innovative easement is allowing the Yellowstone River to move more like a natural river. Channel migration easements forbid impediments that keep the river from meandering and spreading over its natural floodplain.

August 01, 2017

The Yellowstone is called the last, free-flowing river remaining in the continental U.S. It’s true that there are no major dams on the waterway, but there are constraints. For decades, landowners along the Yellowstone have armored its banks with tons of rock and other materials, hemming the river into a set channel rather than allowing it to meander and flow across its natural floodplain. A new type of easement, secured by The Nature Conservancy in Montana and Montana Aquatic Resources (MARS), will free a section of the river to, once again, act like a river. 

Conceived within the last decade, channel migration easements (CMEs)are a special kind of conservation easement that provide an alternative to riverbank stabilization and allow rivers to flow naturally. A free-flowing river will move sediment, woody debris, and vegetation downstream, where it will generate new streamside forests and create gravel bars that provide bird nesting habitat. In the lower Yellowstone, sediment-rich water offers vital habitat for iconic native fishes, including the endangered pallid sturgeon, paddlefish, and blue sucker. Forty-five bird species also have been observed on the property, including bobolink, western screech owl and great blue heron. 

“We believe it’s time to pick up the pace on protecting the Yellowstone River,” says Larry Rau, whose land is under the easement. “We’ve been coasting along but the perils are increasing with more and more demands on the river. My wife and I feel this is a way we can do our part in the efforts of The Nature Conservancy and MARS to have better management of the river.” 

CMEs are purchased from willing landowners who are compensated for land value that is eventually lost through erosion or channel movement – land that might have been washed away by the river anyway. By accepting prohibitions on bank armoring that prevents the river from naturally moving across its floodplain, CMEs can help improve water quality, replenish groundwater and protect against flooding farther downstream. 

Sierra Harris, Freshwater Conservation Program Manager for The Nature Conservancy in Montana, says it’s an exciting project, “The Yellowstone River is a great place to explore channel migration easements as a restoration tool. Over the past 15 years, multiple partners have conducted a massive cumulative effects analysis on the river. There’s a lot of data to support where the channel migration zones are along the Yellowstone.” 

This easement is a pilot project with an ultimate vision of piecing together another twenty migration zones between Laurel and the North Dakota border.   

The property placed in the 190-acre easement is situated in a dynamic location immediately downstream of the Sand Creek and Yellowstone River confluence. It includes both wetland and non-wetland habitat, forming an important link along the continuous Yellowstone River corridor. 

Pallid sturgeon, an endangered species, is known to occur in the adjacent river channel and more than

The Conservancy also hopes to use this restoration tool elsewhere in the state, especially in the Upper Missouri Headwaters Basin.



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 72 countries, we use a collaborative approach that engages local communities, governments, the private sector, and other partners. To learn more, visit www.nature.org or follow @nature_press on Twitter.

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Bebe Crouse

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