River Restoration Must Include Development of In-Stream Complexity: A Historical Case Study of the Machias River, Maine.

Watson, Valerie*¹, Steven Koenig², ¹University of Maine Ecology and Environmental Sciences, Orono, Maine, ²Project SHARE, Eastport, Maine

Rivers in the northeastern USA have a long history of alteration for human use, particularly log drives. One aspect of that manipulation, connectivity and passage, is often the target of restoration funding and effort, but restoration of in-stream complexity is less commonly addressed. The centuries-long history and near universal spatial extent of river alterations may be part of the problem: it is easy to say that a dam is not a natural part of the river, but there is no modern baseline for “healthy” or unaltered in-stream complexity. In lieu of that baseline, we use oral histories, archival records, LiDAR data, and ground truthing to examine the history and extent of human manipulation of the Machias River, Maine. Our research demonstrates the near complete longitudinal alteration and removal of instream complexity since European colonization. The near universal use of rivers for log drives in the northeast makes it likely that most of the region’s rivers are similarly altered. In order to fully restore riverine systems, it is essential that restoration practitioners, researchers, and funders give needed attention to restoring in-stream complexity.