In the third episode of the 11-part series, “How to Read Water,” from Jensen Fly Fishing, Dave explains how fallen timber affects current flow and depth and then shows where you should look for trout. Fly-fishing around fallen trees and other woody debris can be extremely productive.

https://www.orvis.com/fly-fishing
https://news.orvis.com/fly-fishing
http://flyfishalberta.com/jensenflyfishing/

Also look at:
https://flyfishing-blog.com/flyfishing-blog.com/2020/05/07/orvis-how-to-read-water-2-grassy-undercuts/
https://flyfishing-blog.com/flyfishing-blog.com/2020/05/06/orvis-casting-sinking-fly-lines-how-to/
https://flyfishing-blog.com/flyfishing-blog.com/2020/05/06/orvis-striped-bass-on-a-fly/