Lake survey charts are constantly updated to provide accurate information to ship captains. Note the location of dry docks, the bearing and distance between various points, and the opening and closing dates of many of the lakeside harbors.
Nautical charts contain information about the nature and form of the coast, the depths of the water, and general character and configuration of the sea bottom, locations of dangers to navigation, the rise and fall of the tides, locations of navigation aids, and characteristics of the earth’s magnetism.
The mandate to create nautical charts of the nation’s coasts dates back to 1807, when President Thomas Jefferson ordered a survey of the young nation’s coasts. The Organic Act of 1807 authorized the newly formed coastal survey agency to construct and maintain the nation’s nautical charts. This agency, the Office of Coast Survey, is the oldest scientific organization in the U.S. It has been a part of National Ocean Service since 1970, when the National Oceanic and Atmospheric Administration was created.