Beaver dams and their effects on urban streams in the Tualatin River Basin, northwestern Oregon

Introduction

In response to growing interest in beaver-assisted restoration in the Tualatin River Basin of northwestern Oregon, the U.S. Geological Survey (USGS), in partnership with Clean Water Services, collected data from 2016–17 and completed a series of studies to: (1) inventory known locations of beaver dams and activity in the Tualatin River Basin, (2) estimate the number of beaver dams in the Tualatin River Basin as of 2017 and the potential number of beaver dams that could be supported with riparian vegetation improvements, and (3) assess the effects of beaver dams and ponds on storm hydrology, hydraulics, and floodplain inundation, suspended-sediment transport and deposition, and water quality along two urban stream reaches (Fanno Creek at Greenway Park and Bronson Creek between Kaiser and Saltzman Roads). This fact sheet summarizes the results of these studies and implications for beaver-assisted restoration in the Tualatin River Basin.