The effects of unpaved roads on instream sediment: Patterns and challenges for monitoring

Journal of the American Water Resources Association
By: , and 

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Abstract

Despite > 700,000 km of unpaved roads in the western United States, our knowledge of how roads impact instream sediment is unclear. We combined two studies, including (1) a regional analysis linking stream habitat data from a large-scale monitoring program with road density data to identify generalizable relationships between roads and streambed sediment distributions and (2) a targeted field study to evaluate the responses of streambed and suspended sediment collected at locations above and below road–stream connection points to better understand the consistency of responses. Regional analyses indicated a significant positive relationship between road density and fine sediment in pool tails and a significant negative relationship between road density and median particle size. We also found significant relationships between landscape, climate, and local covariates and streambed sediment metrics, where most of the parameter estimates of the covariates were equal to or stronger than those for road density. Field studies suggested higher suspended sediment levels across the seasonal hydrologic regime where roads were open to travel year-round. However, sediment responses to road–stream connection points varied by metric and site. Together, our results indicated negative relationships between increasing road densities and sediment size distributions, but detecting road effects at site scales will be challenging given the effects of covariates that can overwhelm sediment signals.

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Publication type Article
Publication Subtype Journal Article
Title The effects of unpaved roads on instream sediment: Patterns and challenges for monitoring
Series title Journal of the American Water Resources Association
DOI 10.1111/1752-1688.70006
Volume 61
Issue 2
Publication Date March 02, 2025
Year Published 2025
Language English
Publisher Wiley
Contributing office(s) Northern Rocky Mountain Science Center
Description e70006, 15 p.
Country United States
State Montana
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