Taking the soft approach to river bank stabilization

By Michael Howell

Three landowners on the west side of Stevensville along the east bank of the Bitterroot River have banded together and with the help of grants and a plethora of local and out of state volunteers, have managed to design and implement a river bank stabilization project which could prevent their property from being washed downstream. If it works, it would also help prevent the river from cutting across the floodplain toward the Town of Stevensville’s sewer treatment plant which sits nestled in the floodplain to the north.

The Hunters, the Groves, and the Notaros were all facing a common problem. The river was eating away at their property at a fast pace. Tim Hunter estimates that he lost about 40,000 cubic yards of earth from his property alone. Like a growing number of landowners along the river, this neighborhood group decided to take a softer approach to bank stabilization and avoid the use of rock rip-rap as much as possible. What they found out is that the alternative is a lot of work. But they also found a lot of help.

They got help from organizations such as the Clark Fork Coalition, the Bitterroot Water Forum, and Bitterroot Audubon and the Bitterroot Conservation District and were successful in pulling down grants worth a total of $35,000.

They got volunteer help like you wouldn’t believe. The landowners, along with friends and neighbors and other local volunteers, have spent the last five weeks gathering willow cuttings to  be planted along the river bank. A team of student volunteers from Colorado Mountain College in Leadville, Colorado, showed up for some hands on experience in state of the art style riverbank stabilization.

Unlike traditional rip-rap where large angular stones form a rock blockade which speeds up the water flow and deflects it towards downstream banks, this alternative style slows the water and creates riparian habitat.

The bank is built up in layers, first by placing a row of bundled tree cuttings down. In this case that included a tree thinning expedition into the local forest and a Christmas tree collection campaign. Bundles of willows, called fascines, are laid on top of geo-textile fabrics made from coconut fiber that have been staked out along the bank. These are then covered with earth and another similar layer is developed on top of it. The final bank will be four layers thick. Willows will be planted and irrigated for a number of years. The 310 Permit from the Bitterroot Conservation District permitting the work calls for five years of maintenance and repairs if necessary.