Effects of beaver dams and ponds on water quality in urban streams of the Tualatin River Basin, northwestern Oregon
Year: 2025
Type: report
Abstract: This is the fourth of four reports in a multichapter volume assessing the capacity of the stream network to support beaver dams and evaluating the effects of beaver dams and ponds on urban streams.These reports document the data collection from 2016-17 and the findings of these studies, which were done in partnership with Clean Water Services.Chapter A (White and others, 2025a) documents the locations of beaver dams in the Tualatin River Basin and how many beaver dams the stream network could support with existing and improved riparian vegetation.Beaver dam capacity was estimated by modifying existing tools to account for the low gradient of many streams in the Tualatin River Basin.Chapter B (White and others, 2025b) describes the effects of beaver dams and ponds on hydrologic and hydraulic responses of storm flows.Hydrologic and hydraulic responses for two urban stream reaches were compared with and without beaver dams and ponds and for a range of streamflow conditions using two-dimensional hydraulic models.Chapter C (Doyle and others, 2025) characterizes the effects of beaver dams and ponds on the transport and deposition of suspended sediment.Continuous turbidity, discrete suspended-sediment samples, and streamflow measurements collected during storms and base-flow periods were used to assess: (1) suspended-sediment loads upstream and downstream from two beaver-affected reaches, and (2) seasonal and longitudinal turbidity patterns.Chapter D (this report) describes the effects of beaver dams and ponds on longitudinal, spatial, and seasonal water-quality patterns.Continuous and synoptic water-quality data were collected along urban stream reaches, and net ecosystem production was calculated for two beaver-affected reaches.The findings of these studies illustrate that the effects of beaver dams and ponds on hydrology, hydraulics, suspended-sediment transport and deposition, and water quality are dependent on the characteristics of a stream reach (for example, channel gradient, groundwater exchange, and riparian vegetation) and the characteristics of beaver dams and ponds along that reach.This information can be used to consider the implications of beaver-assisted restoration in the Tualatin River Basin and the effects of beaver dams and ponds in urban streams.Designing and implementing this study were large tasks, and the authors are thankful for the assistance of several people and organizations.James White and Micelis Doyle (retired) (part of the U.S. Geological Survey [USGS] beaver team) provided useful discussions and support for the data collection and analyses.Dave Piatt (USGS) assisted with site installations and Amy Brooks (USGS) helped with the processing of all time-series water-quality datasets.Field assistance was provided by USGS employees, including Alexandria Costello,
Source: Scientific investigations report
DOI: 10.3133/sir20255039d
Language: English
Subfield: Ecology
Field: Environmental Science
Domain: Physical Sciences
Open Access status: bronze
Funder: U.S. Geological Survey
OpenAlex ID: W4414645495