I've saved this article for years. Reading Water Tutorial:
There are 3 things you got to ask yourself before you decide if the section of river you are fishing is "Steelhead water" and will you have a chance of catching these magnificent fish.
1.) Adequate depth to protect the fish from predators, boaters, and anglers. Rarely will you find a fish in water less than 2 1/2 feet, try focusing on water that is in the 3-15 foot range.
2.) Current Velocity, the best speed would is anywhere from a slow walking pace, to a slow jogging speed. Remember Steelhead want to get from point A to point B using the least amount of energy required. They don't want to be battling rapids, but they like a little water disturbance.
3.) River bottom structure, Steelhead DO NOT like sand..Sand irritates a Steelhead's gills. They will rarely hold in sandy bottoms. Instead look for structure that consists of small to medium sized boulders. These could be the size of a baseball, basketball, or bigger.
Pocket water: Pocket water is associated with swift water and structure. In a boulder-strewn rapid, there are areas of slower/slack water that may be found in front of, behind, or beside large rocks. Float fishing is a very effective technique for fishing boulder strewn water, and pocket water. Spoon fishing is also a very effective technique, especially during the winter months when Steelhead are lethargic.
Side Channel: A well defined narrow band of deep water that is surrounded/bounded by shallower water. These are often by the rivers edge and are darker than the rest of the water surrounding it. Think of these as a fish highway, migrating fish will move up this stretch of water when they can find depth/structure to make them feel secure.
Tailouts: The smooth/slower water upstream from a rapid/faster flowing section of water is a tailout. Tailouts are usually anywhere from 1-5 feet deep, and 20 to 100+ feet long. Tailouts have flat unriffled surfaces, and is the shallowest holding water. Fish are more exposed in a tailout and are on the alert more than a fish in a pool or back eddy.
Pools: These are anywhere from 5-20 feet deep, and at times are a good bet to find Steelhead. I start at the top section of the pool, and work my way downstream covering this water thoroughly. Work through the water column covering all aspects of it. However: Just like in Bill Herzogs book he stated that fish in deep pools are suspended, so your offering doesn't necessarily have to be near the bottom. Unfortunatly I can't get the pics to post with this article.