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	Sedimentation and Erosion High rates of sediment input and accumulation negatively impact the human and natural environment. Excess erosion and sedimentation can be harmful to freshwater and saltwater habitats, cause changes in bay depths and water circulation patterns, degrade water quality, and lead to increased flooding. In the Tillamook Bay Watershed, logging roads, forest fires, agriculture, and development have contributed to sediment problems by reducing vegetative cover and compacting soils. Vegetative cover encourages rainwater to penetrate the soil by slowing water in its foliage and by offering root pathways as routes for rainwater to penetrate the soil. Areas without vegetation experience increased runoff and erosion. Forestry practices have improved dramatically during recent years, but past logging practices and old logging roads still cause landslides that can quickly deliver excess sediment to streams and the bay. While landslides are natural events that may occur on steep slopes during prolonged and heavy rains in Tillamook, the removal of vegetation has likely changed the timing, size, and composition of these events. Chronic sediment inputs include roads that were built prior to current design standards with surfaces, cut and fill slopes, and ditches that are constant sediment sources. Livestock may also contribute to erosion and sedimentation by trampling streamside vegetation. Development, too, creates impervious surfaces where rainwater cannot soak in and disturbed or barren areas where runoff and erosion increase. Image and Data Credits What's Next? See what we're doing to reduce sedimentation and erosion.