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Contour Map Reading
Greg Myers

You wouldn't think about driving through several states without a highway map. Neither should you go fishing without a lake map, especially if it is your first time on the lake. For safety reasons, it will show you where there are shallow parts in the middle of the lake. For fishing reasons, it will show you where the structure is on the lake that is away from the shoreline. With an accurate contour map of the lake you will be able to determine productive fishing areas before you reach the lake to put your boat in the water.

Contour lines draw the shape of the bottom by revealing a specific depth throughout the lake. Try to purchase maps that have contour lines no more than ten feet apart. A first hand inspection with a depthfinder and fishing lures is necessary before you can visualize the bottom accurately. Reservoir maps tend to be more detailed, because they are usually made before impoundment while the eventual lake bottom is visible to the naked eye. Maps of natural lakes are less detailed and often overlook major structural elements, such as humps. Nevertheless, contour maps provide a good feel for the lake and get you started in the right direction.

Contour maps are usually available at bait and tackle shops near popular lakes and impoundments. Many lake maps point out navigation markers, roads, and trails around the lake, as well as the locations of marinas, resorts, restaurants, and campgrounds. Some reservoir maps may also show submerged buildings, roads, railroad tracks, bridges, stumps, trees, ponds, and other structures. If you plan to visit a lake for a vacation, call or write the local chamber of commerce or a local bait and tackle shop and see if they can provide you with maps before you go. The state’s department of natural resources may be another source for maps.

In many cases, the best maps are those published by the U. S. Army Corps of Engineers or the Department of the Interior, Geological Survey. These topographic maps, as they are called, may not show the depth contours of some natural lakes, so check before buying them. If the lake you’re interested in is within the jurisdiction of the U. S. Army Corps of Engineers, they may have a map. I buy my maps at Ridgeways on 41st St. in Tulsa.

When dealing with reservoirs, dated maps that were printed before the lake was impounded are often the best. If you get a map that was made before impoundment, outline the shoreline with a felt pen. You must first determine the normal pool elevation of the lake, which is usually listed in the margin of the map in “feet above sea level”. You may also get this information from the U. S. Army Corps of Engineers. Simply find the contour that coincides with the lake’s normal pool elevation, and follow the contour with a marking pen. This is what that I had to do with my McGee Creek map.

Along with contour lines, the may have other marks and symbols showing foundations, roads, and many other bottom features that may hold bass. A publication entitled Standard Symbols, available from the Geological Survey, will make it easier to identify such features on the map.

Your ability to read contour lines, more than anything else, will determine how well you interpret the shape of the bottom and locate underwater hot spots. A submerged point, one of the most prominent structures, appears as a series of contour lines pointing away from the shoreline like a finger. The photo to the right shows a point. A drop-off exists where the contour lines come close together. A reef, hump, or submerged island appears a s a contour line in an irregular circle surrounded by deeper circles. The more you learn about map reading, the better you will become at finding these and other structures.

When looking for structural elements, keep in mind the season of the year. Pick out several spots on your map that appear to have potential, then find them on the water. Say that you want to check out a submerged point that reaches far out from the bank before dropping into deeper water. Your map will get you to the general vicinity of the point. Then you must use your depthfinder to determine the exact location and shape of the point.

Begin by crisscrossing the point a few times to get a general feel for it. Then follow the outline of the point at a specific depth, such as ten feet deep. Drop marker buoys at intervals as you follow the point's ten-foot contour. When you’re finished, the markers will outline the point, making it much easier to visualize the point's shape. Remember, bass are edge oriented, whether they are using shallow cover or a deep structure. Should your depthfinder reveal an especially promising feature, such as a stump or rock pile, mark it with a buoy.

After marking any promising structure with buoys, fish it with a bottom-bumping lure, such as a Texas-rigged plastic worm. Doing this, you can feel the bottom through your rod tip. This is an important part it will help you determine whether the bottom consists of mud, gravel, rock, or some other substance, and will let you know if the structure has weeds, boulders, stumps, or other features that attract bass. Very often a single stump or small patch of weeds may hold an entire school of fish. Note the spot’s location even if it fails to produce, because it may hold bass at another time.

Before retrieving your markers, locate landmarks so you can quickly find the place at a later time. First find an obvious object on the shoreline, such as a dock. Then line up another object directly behind the dock, perhaps a house. Find another shoreline object at right angles to the dock and line it up with another that is directly behind it. Record these landmarks on the topo map or in a notebook. When you return, position your boat so that the landmarks line up and you will be directly over the structure.

By using a lake map and a depthfinder, you can learn more about the bottom of a lake in a few days than you could in years of fishing the lake without these tools.