Hells Canyon is the deepest river canyon in the United States. Now scientists have solved the mystery of when it formed.

Smolt releases resumed at Hells Canyon Dam in 2021, so this year’s season is more typical, with a start in late April rather than mid-May, and the 2024 season should be as well. You Might Like ...

That’s according to a new study that looked at ancient river sediments that have long been hidden away inside the canyon’s caves, which now lie high above today’s Snake River. This new work ...