Hydrographic signal on the shores of the reservoir of Grand Coulee Dam.
Used as signal for navigation by three-point sextant fix.
Image ID: theb4330, NOAA's Historic Coast & Geodetic Survey (C&GS) Collection
Location: Washington, Grand Coulee Dam, Columbia River
Photo Date: 1948
Credit: Family of Captain David M. Whipp, C&GS
• High Resolution Photo Available