Reclamation Information Sharing Environment (RISE)

The Bureau of Reclamation deployed 600 tracer clasts labeled with Passive Integrated Transponder (PIT) tags on gravel bars in the Methow River in the vicinity of the Sugar Levee near Twisp, WA in October 2018. The purpose of the experiment was to test a hypothesis that the Sugar Levee is disrupting sediment transport dynamics through the study reach and causing ‘excess’ deposition on a gravel bar downstream of the levee, resulting in bank erosion and property loss on the opposite bank. Searches for the tracers in 2020 and 2021 recovered and surveyed the locations of 448 (75%) and 356 (59%) of the rocks installed. Many rocks remain on the bar where they were installed, but a few have traveled more than a mile. Rocks installed on two bars adjacent to the levee are much more mobile than tracers installed further upstream. This is likely due to an increase in channel slope caused by incision adjacent to the levee.