Topographic maps, or topo maps for short, are an incredible resource for anglers. Today, nearly every lake has a detailed map with one-foot contours available for free on the internet, giving anglers easy access to the layout of their home water, or any other water they choose.
How do I read a topographic map?
A topo map uses lines known as contours to display the elevation of land, or the depth of a body of water, in an easy to read two-dimensional format. Contours represent a change in depth at whatever interval your specific map uses. Most common in one foot, meaning the depth changes by one feet between two contours. This means the closer the contours are together, the steeper the grade.
Note: Usually the contours will be labeled with a number, Indicating it is that many feet deep at that specific spot.
Many of the tools available today that provide topographic map data also employ shading to show a high-level overview of general depth, as shown below. The darker the color, the deeper the water.
Here are some very poor drawings of how topographic contours look in reality
There are a number of different sources of topo maps that are available to anglers, and many of them are free. Navionics (link to card) is available online for free at webapp.navionics.com and map cards are available for purchase for your fishfinders. Lakemaster (link to card) is available exclusively for Humminbird electronics. You can purchase the maps for individual lakes online or on their app. Both of these sets of maps are created by the companies that own them. C-MAP (www.genesismaps.com/socialmap/) is an open-source mapping site where anybody with a boat can record mapping data and upload to a public (or private if you have a paid account) database. The unique feature here is that small bodies of water like ponds often have maps for you to use, which is not the case with other options. It’s also the most accurate, but large bodies of water are often incomplete.