Water column is fancy fly fishing lingo for depth. But the concept of water columns may help illustrate when discussing levels of depth that trout may be holding at. That is if one can overlook the fact that in fly fishing we talk about top column, middle column, and bottom column, which seems to imply the columns runs horizontal instead of vertical. (Environmental studies are given credit for this term where it seems to reference a vertical column, so to be correct we should refer to the top, middle and bottom sections of the column.) Now that we have that out of the way, or perhaps placed it in the way, let’s get on to talking fishing. Trout typically consume the vast majority of their caloric intake below the surface. And figuring out the water column trout are working is key to fishing success. Visual observation is the simplest way to determine this. The top column is the portion of water right below the surface, and fish in this area are obviously the easiest to spot, they also tend to be the most wary and stealth is vital. The fish in this depth tend to be feeding on emergers, cripples, spent wing spinners or duns that have fallen back in. As a fly fisher you must devise a strategy to approach and cast to these fish without spooking them, once spooked the game will be off for awhile. The middle column is the most likely area for trout as they can feed easily from the top to bottom, fishing a dropper system is ideal when trying to locate fish in this area, as it allows you to fish and two columns at once. The bottom column is the hardest to fish and visually, hard to pinpoint fish, but it tends to hold the larger fish, although they might not be actually feeding. It is also the hardest to control your fly’s drift and to detect strikes, as multiple currents detach your ability to ‘feel’ your fly. Strike indicators are of great value, when searching water columns and detecting strikes. Move them up or down on your leader as an aid in controlling the depth of your drift. A Palsa indicator will go into the water giving you a visual aid as to the underwater drift of your fly. Xink or split shots help you get your fly down. Xink is especially useful where split shot is illegal or if you want just a small amount of sink. Casting placement effects your depth as well, further upstream you cast gives your fly more time to sink before hitting the portion of the drift you are working. Fly weight is important as well. Beadheads obviously add weight to standard nymphs and streamers. And certain pattern like Copper John or others made of wire are heavier. And finally fishing sinking line will greatly reduce sink time as well. Although for many nymphing situations floating line will work just fine. Adjustments can be made throughout the day as needed or through different sections of water, to move your fly up or down through the water column as you see fit. If you have nothing to go on, try starting with the dropper system through the middle column and gradually go deeper until you find fish or until your visual cues tell you something different..