This installment of reading water deals with details for the fast water types described in part 3. I suggest that you print them or save them to your machine for reading off line at your leisure. Rapids, riffles, pools, pocket water, slicks, eddies, these are the types of water you fish in a river or stream. In the last installment I glossed over each type of water to give you a way to go to the stream and try out your new knowledge. Now it is time to get into details.
Rapids are the fastest water flows in a stream.
They are at least three feet deep and usually have shallow areas and deep pockets that the current has dug out of the streambed. In order to be able to find these different areas, a little information on hydraulic action of water currents is needed. To begin we will look at the effect the streambed has on current flow. You can check this in an area with a weighted nymph on a long, fine leader, in clear water. Cast up stream and watch the speed of the nymph as it sinks, you will be able to discern several different flow rates as the nymph sinks and you might even see a change in direction of the drift.