Practical guides to reading lake depth maps, finding public access, and using state survey data to plan a day on the water.
What contour lines, intervals, and spot soundings on a bathymetric map actually tell you about structure, and where the map stops being trustworthy.
Where Wisconsin DNR depth charts come from, how to tell a 1940s survey from a sonar-era one, and how to read the survey date before you trust a contour.