Oregon & Northern California Coastal is a freshwater ecoregion in western North America. It includes the coastal rivers of Oregon and Northern California, from the Columbia River mouth in northwestern Oregon to northern Monterey Bay in Central California. It includes the Umpqua, Rogue, Smith River, Klamath, Mad, Eel, and lower Russian rivers, and many smaller coastal rivers and streams, including those on the coast side of the Marin and San Francisco peninsulas.