The Coos Bay estuary is located on the Oregon coast at Coos Bay and North Bend. The estuary is approximately 13348 acres in area and has a watershed of approximately 1058 square miles.

The Coos Bay estuary is designated as a Deep Draft Development estuary under the Oregon Estuary Classification system. The geomorphology of the area is that of a Drowned River Mouth estuary.

The Coos Bay estuary is located in Coos County. Timber and fishing are the foundation of the county's economy. The area also produces large quantities of shell fish. In addition vacation and recreational possibilities, such as the National Dunes Recreation Area and many state parks, attract tourists to the area and provide an additional economic stimulus. There are several port districts in the county: Port of Coos Bay founded in 1909, Port of Coquille River founded in 1912, and Port of Bandon founded in 1913. Coos Bay is considered the best natural harbor between San Francisco Bay and the Puget Sound and the Port of Coos Bay is the largest forest products shipper in world. The first census in 1860 showed a population in Coos County of 445. The 1997 population of 61,400 represented a 1.9% increase over the 1990 population.

Ride the tide up a sinuous arm of Coos Bay on a designated canoe route through the federally protected South Slough National Estuarine Research Reserve. Oystercatchers, egrets, herons, and many other birds stalk the mudflats of this estuary. The nation's first Estuarine Research Reserve was established here in 1974 on seven square miles of abandoned farmland and cut-over forest bordering Coos Bay's South Slough. Today there are 27 estuarine research reserves nationwide. Many are watching the reclamation experiments taking place at SSNERR to see how wildlife and plants flourish when estuary dikes are breached and upland forests allowed to regrow. Displays in a modern interpretive center help explain the research, but the canoe route and a network of easy trails nearby allow you to investigate the reserve first hand.