The article is an excellent introduction to the standard approach to reading the water. It is analyzing the hydraulics of the river and the needs of the trout to determine the likely holding areas for fish. It deals with the PHYSICAL characteristics of the river. He describes this as one of two fundamental skills, the other being presentation. "Successful fly-fishing is built around two fundamental skills: Reading water and presentation."
Allow me add a third fundamental skill. I think of reading the water as a process of 3 and not 2 parts/layers. The second layer and a third layer are reading the food and reading the approach (presentation)
It is well known that certain water types hold certain types of food. Riffles for example hold the clinging and crawler type of mayfly nymphs and some stoneflies. Faster water with a greater gradient hold stoneflies and clinging mayflies. Rapids/heavy riffles are too fast for crawlers. Slow water hold burrowing mayfly nymphs. Vegetation can hold scuds. Water near the shore or under trees have terrestrials.
What I am saying is that not all water types hold all types of food. You can read the physical characteristics
of the river to understand where trout are likely to be, but reading the biological characteristics
; the food in that location should be the next step to reading water. If we read the food correctly, we are more likely to be successful.
The third step is reading the approach and presentation. Where is the best location to stand and what cast(s) should be made. This is highly individual and is determined by your own personal wading and casting skills and how you want to fish the water.
As you read the physical
nature of the water, simultaneously read the biology (food)
which is present, and your possible forms of presentation
. If you think only about the narrow definition to reading the water, you would not think of fishing a beetle or ant downstream from overhanging trees.
I wrote an article for our TU chapter about the 5 major choices in fly fishing success that describes Norm Albiston's approach which goes a bit further.