A mooring point on the Snake River near Ice Harbor Dam has been declared extremely hazardous.
The structure, Hard Rock Dolphin 4, has been declared unsafe after a routine inspection this week by the U.S. Army Corps of Engineers.
In a release, Corps officials said all commercial and recreational vessels are warned to avoid the location until the structure has been removed.
The structure is one of six mooring points upriver of Ice Harbor Dam. They are used for temporary moorage.
Dolphins 3, 4 and 5 were declared unsafe for use in February 2009 and are posted with warning signs. Dolphins 1, 2 and 6 are sound and remain in service.