READING AND MAPPING STILLWATERS
Reading and mapping a lake or pond should be the angler's first step toward successful stillwater fishing. Determine all you can about the physical characteristics of the stillwater, such as shape and surrounding habitat, and note these items on a map of the stillwater. Then the successful stillwater angler will chart in the structures of the lake or pond in question. The following is a basic list of structures that one should look for:
1. Inlets
2. Outlets
3. Old streambed channels
4. Shoals
5. Cliffs
6. Shoreline trees or other overhanging vegetation
7. Boulder Fields
8. Flooded Timber
9. Sunken Logs
10. Submerged weed beds & depth
11. Areas of floating weed beds
12. Springs
13. Shallows with steep drop-offs
14. Shallows or flats
Not all stillwaters will have all of these items. After the angler has charted the needed items into the map, additional notes are added about areas where certain angling methods or trout behavior has been noted. Compiling this information will often take the angler a few seasons to complete, but the rewards are well worth it as the more knowledge you have about the stillwater you are fishing, the more effective you will be when you fish it.
Also remember that not all of the weed beds or other aspects will be important throughout the entire year. Often, like the food forms, certain structures are important during certain time periods. These factors must also be noted. The angler should also note areas where trout are spooky and hard to approach. The effects of wind and how it affects the trout and the fishing should be noted. Note places such as cliffs and other areas which may be used for observation.
LAKE TYPES
Natural lakes are often times categorized by their age. There are oligotrophic (young) lakes, mesotrophic (middle-aged) lakes, and eutrophic (old) lakes. Many of the high mountain lakes in this area [Montana] are classed as oligotrophic and the rest are classed as mesotrophic. We have few, if any, natural eutrophic lakes in this area.
We also have many man‑made impoundments such as Holter and Canyon Ferry. Often impoundments have many of the features of eutrophic (old) lakes. An excellent example would be Ennis Lake, which is shallow, weedy, has a gradual shoreline taper and muck bottom with extensive sedimentation. In fact, this lake is less than 100 years old.
There are also strip mine pits and farm ponds. You will find that Montana is dotted with all kinds of stillwaters which offer the angler excellent fishing for both warm and cold water species.