Siletz Bay National Wildlife Refuge, National wildlife refuge in Lincoln County, Oregon, United States

Siletz Bay National Wildlife Refuge is a set of discontinuous tracts north and south of the Siletz River where it enters Siletz Bay, south of Lincoln City. It is one of six refuges in the Oregon Coast National Wildlife Refuge Complex. Its diked former pastureland holds tidal marsh, and U.S. Route 101 runs through the refuge.

Siletz Bay National Wildlife Refuge was established in 1991 to return diked and ditched salt marsh to its natural state; the land had been pasture for dairy cows. Near Millport Slough, the U.S. Fish and Wildlife Service, Ducks Unlimited and the Confederated Tribes of Siletz restored a 100-acre tidal marsh, breaching 220 feet of dikes, removing 9,300 feet of dikes and filling 1,200 feet of ditches.

The Confederated Tribes of Siletz joined the U.S. Fish and Wildlife Service and Ducks Unlimited to restore 100 acres of tidal marsh at Millport Slough, an arm of the lower Siletz River. Their crews breached 220 feet of dikes, removed 9,300 feet of dike and filled 1,200 feet of ditch, adding woody debris for fish habitat.

The Alder Island Nature Trail, opened in 2017, is a 0.85-mile (1.37 km) round trip for visitors on foot. A boat launch gives access to non-motorized craft. U.S. Route 101 runs through the refuge, which lies just south of Lincoln City.

The bleached snags along U.S. Route 101 date from the era when the salt marsh was diked and ditched for dairy pasture. Salt killed the trees, and their bare trunks now give red-tailed hawks and bald eagles open perches over the marsh. The dikes themselves were later removed: 9,300 feet of them, plus 220 feet breached at Millport Slough.