Just got back from the San Juan River. I did not use the Tenkara rod, but did use a Euro Nymph rod to accomplish the same results.
I have used the Tenkara rod on the San Juan River. I have landed several 21 in. Rainbows with the Tenkara rod in shallow water that I could wade. However, I had several break off when they would run on me and I couldn't follow because of deep water.

See "Fishing San Juan River Sept 11 and 12, 2019" under Fishing Reports: