Coast Guard Aids to Navigation Team Astoria, Ore., crew members prepare the foundation for a navigation structure on a rock at the entrance to Cathlamet South Channel just off Tongue Point in Astoria, April 11, 2013. Construction of the navigation structure required careful planning and minus tides as the rock is usually submerged beneath the waters of the Columbia River. (U.S. Coast Guard photo by Chief Petty Officer Kevin Bentle)