Decreased permeability leads to increased runoff which causes erosion and increased sedimentation into waterways. Roadway construction along riparian areas create soil destabilization and erosion. An aspect of erosion that contributes to increased sediment transport is mass wasting and slides. Mass wasting is the downhill transport of material primarily under the direct influence of gravity without substantial aid from flowing water or ice, or wind. Environmental factors such as water, can exacerbate this condition.
Mass wasting can increase the volume of sediment transported in disturbed areas.
Another aspect of erosion occurs superficially on roadways. Suspended sediments can be attributed to poor locations of roads, construction, and maintenance. The addition of suspended particulates makes its way into salmonid spawning gravel where it settles and chokes nests and developing fry. The problems are further compounded when roadways are located near streams and water. Concentrations of intragravel fine sediments can be attributed to mass soil movements and erosion.