In this great video from Jensen Fly Fishing, Dave explains how to fish a streamer through a riffle that flows over a shelf into a deeper pool. The keys are using the proper fly and leaver to get the pattern down quickly and working from the bottom of the riffle up into the prime lie right below the drop-off.

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

Also look at:
http://flyfishing-blog.com/flyfishing-blog.com/2020/09/12/orvis-pro-wader-fabric-and-construction/
http://flyfishing-blog.com/flyfishing-blog.com/2020/08/11/orvis-how-to-fish-woolly-buggers-in-rivers-part-iii/
http://flyfishing-blog.com/flyfishing-blog.com/2020/08/04/orvis-how-to-fish-woolly-buggers-in-rivers-part-ii-the-dead-drift/