By Shawn Prochazka
The Piedra River and most of Pagosa Country’s streams are low and warm. Streams in the lower elevations are low and warm. Hooking, fighting and releasing trout is often fatal to the fish in these conditions.
San Juan River in 2023
I did a study of the San Juan River flow and temps in 2023. That year we had decent snowpack followed by a bad monsoon. Flow dropped below 100cfs by the end of July and was 30-40cfs by the first week of September.
San Juan River temps in 2023 peaked late July into early September.
The highest temp for the San Juan River in Pagosa in 2023 was 78 degrees – occurred 2 Aug, 19 Aug, 25 Aug, and 30 Aug.
The average diurnal change between low temperature and high temperature was 15 degrees – example: 60 degrees, an hour or two after sunrise, and then 75 degrees shortly before sunset.
The average maximum temperature each day occurred 3pm to 6pm – quite a bit of variance. The average minimum temperature each day occurred 6am to 8am.
2025 is worse…
Our mountains had 50-60% of snowpack and our monsoon has been slow to start.
San Juan River flow in Pagosa dropped below 50cfs on 7 July. For perspective, that’s already well below the 25th percentile of 128cfs, but better than worst of 19cfs in 2002.
Water temps climbed into the trout danger zone starting the afternoon of June 18.
I’m a big fan of Montana’s “Hoot Owl” restrictions. In order to protect the trout, Montana does not allow fishing each day from 2pm to midnight on specified waters.
Colorado Parks and Wildlife – CPW – has a similar voluntary program, but I rarely hear much about it.
What can you do?
Fish early and be done by 1pm.
Fish up high – above 10,000 ft.
Thankfully our trout can move around in streams and find cooler water for refuge. A large die-off unlikely. But harassing the trout while they’re already stressed will often lead to dead trout.
Let’s protect our streams, and our trout!
Shawn Prochazka is part of the team at Pagosa Weather. Learn more at PagosaWeather.org