Tillamook Bay Drainage Basin Erosion and Sediment Study, Oregon

Excerpts from the report: The Tillamook Bay Drainage Basin is located in northwestern Oregon. It is bounded on the east by the crest of the Coast Mountain Range and on the west by the Pacific Ocean. The three resource areas considered in this study cover a total of 363,520 acres of which 323,050 acres are brush, cutover, and forested land on moderate to steep slopes and deeply incised canyons; 29,490 acres are non-forest and flat to gently sloping urban, agricultural and miscellaneous land; and 10,980 acres include the rivers and bay area. our large rivers, the Wilson, Trask, Kilchis and Tillamook enter the bay from the southeast while a fifth large river, the Miami, enters from the north and just opposite the entrance to the bay from the Pacific Ocean. Sediment in Tillamook Bay is a major problem. The continual deposition of sediment in the bay has caused adverse effects on shipping and navigation, commercial and sports fishing, oyster production and clamming, and on environmental and aesthetic qualities of the basin. The objectives of the study are to: (1) Inventory the gross erosion rates by suitable categories under present conditions, (2) Estimate the sediment yield under existing use and management. (3) Develop and evaluate alternative measures and land use management plans, (4) Estimate future sediment yields for various alternative land use management plans, (5) Assess economic effects of soil erosion and sedimentation, and evaluate economic consequences of proposed alternative solutions or plans. (6) Recommend opportunities for implementation of erosion and sedimentation control measures.