The Snake River at Flagg Ranch, Wyoming

The Snake River monitoring site

NPS

The Snake River is the largest tributary of the Columbia River. It originates in western Wyoming and flows through Idaho and Oregon before converging with the Columbia River in Washington state. Its drainage basin also includes parts of Utah and Nevada. The Greater Yellowstone Network samples the Snake River in Wyoming above and below Jackson Lake. Here, we focus on the Snake River monitoring site above Jackson Lake, at Flagg Ranch, WY. At this location, the Snake River has a drainage area of 486 mi² (1259 km²) and runs west and then south for 47 miles (76 km) from its source on the Two Ocean Plateau to Jackson Lake. Its headwaters rise over Yellowstone National Park, meander in and out of Bridger-Teton National Forest for 10 miles (16 km), and then into the John D. Rockefeller, Jr. Memorial Parkway, which is co-managed with Grand Teton National Park.

This segment of the Snake River has been designated "wild" under the Craig Thomas Snake Headwaters Legacy Act of 2008 (JPL 111-11), an amendment to the 1968 Wild and Scenic Rivers Act. Tributaries include Heart River and Lewis River, both of which originate in Yellowstone National Park from lakes bearing the same names. The entirety of the watershed for this river section is located within National Park Service and U.S. Forest Service lands.

Map of the watersheds associated with the Snake River segment monitored at Flagg Ranch, WY.

NPS

An overview of the Snake River at Flagg Ranch, WY, sampling site (denoted by the yellow star) located below the confluence of the Snake River and Lewis River.

NPS