Yellowstone River

From Yellowstone National Park through Paradise Valley.

The Yellowstone runs roughly 671 miles, according to the NPS, from its headwaters in Wyoming's Absaroka range, through Yellowstone Lake, out of the park at Gardiner, and across Montana to its confluence with the Missouri in North Dakota. Montana FWP describes the upper river — more than 180 miles from the Wyoming line to the Clarks Fork — as free-flowing, with no dams or river-wide diversion structures.

Inside the park, the Yellowstone holds native Yellowstone cutthroat trout. The river is managed accordingly (a July 1 opener for the Yellowstone River under the 2026 park rules, with additional reach closures and native-fish release requirements). Check the NPS regulations for each specific reach before fishing.