07/01/2020
“Messy rivers are healthy rivers” -Dr. Ellen Wohl
Dynamic, active river floodplains create some of the most biologically rich and economically important ecosystems in all of Montana. These broad, beautiful floodplains full of cottonwood galleries, willow thickets, and side channels are all the result of those rivers being free to move back and forth over time. What this basically means is that river banks need to erode because the river system desperately needs that sediment. A river can be thought of as a long, skinny, linear system. And from that perspective, erosion does not destroy land, it just moves it downstream. Sediment eroded from a bank along one part of the river is deposited along another, and willows, cottonwoods, and many other riparian plant species are entirely dependent on that freshly deposited sediment to germinate and grow. Not to mention the spawning fish, invertebrates, and shorebirds that enjoy freshly deposited sediment too!
A migrating river also topples trees and takes shortcuts across the floodplain, leading to side channels, backwaters, log jams, and floodplain pools. These are not only important habitat features for a huge number of wildlife species, they also force the river’s water to fill the floodplain. The water flows through a multitude of channels on the surface but is also pushed below the ground, where it is slowed down, cooled, and (at least temporarily) stored. Given the importance of water resources to all aspects of life in Montana, it is easy to see why maintaining messy rivers is vitally important to the future of humans and wildlife alike.