Bighorn River

About

Bighorn Canyon NRA — 1966 Designation, Crow Indian Country. The Bighorn is a 461-mile tributary of the Yellowstone-Bighorn system. It rises in Wyoming's Absaroka Range, gathers itself at the Wedding of the Waters where the Wind River becomes the Bighorn, and eventually crosses the Montana border to join the Little Bighorn near Hardin, Montana. The featured Wyoming reach runs 112 miles through Fremont, Hot Springs, Washakie, and Big Horn counties. USGS gauge 06274300 records an average flow of 1,685 cubic feet per second, with an optimal boating window between 850 and 2,550 CFS.

Long before dams or gauges, this was Crow country. The Crow people arrived in the Bighorn region in the early 1700s and were promised reservation lands in the 1851 Fort Laramie Treaty. The river flowed through ancestral Indigenous territory as a primary travel corridor, hunting ground, and gathering place, though the 1800s-era treaties, the 1830 Indian Removal Act, and the 1840s–1890s allotment era established the cession framework that dismantled that tenure. In 1876 the Battle of the Little Bighorn — Custer's Last Stand — was fought on the Greasy Grass River, the Little Bighorn, a Bighorn tributary.

The watershed's industrial century came next. From the 1830s through the 1920s the Bighorn watershed was logged to feed the 1850–1910s regional timber industry and the 1860–1910s railroad expansion. Local sawmills, logging drives, and downstream lumber operations were the major operators. Three forces ended large-scale cutting: the 1910 exhaustion of the old-growth stands, the 1915 start of state forestry conservation, and the 1930s establishment of state forests. Meanwhile the first hydrological studies took shape — the 1870s–1890s USGS survey, the 1880s–1910s establishment of USGS gauging stations, and the 1910s–1930s state geological survey streamflow assessments.

The defining transformation came in 1966. Congress authorized the Bighorn Canyon National Recreation Area, incorporating lands acquired from the Crow Indian Reservation by the Bureau of Reclamation. In the same year engineers completed Yellowtail Dam, a concrete structure rising 525 feet above the riverbed, which impounded the water into Bighorn Lake. The reservoir carries the name of Robert Yellowtail, the first Crow tribal member to head the Bureau of Indian Affairs. The Recreation Area preserves a 60-mile stretch of the canyon along with 120,000 acres of prairie, canyon, and badlands — a landscape where geology and engineering sit visibly side by side.

The river's modern chapter is one of repair. Since 2010 the Wyoming DNR, working with local watershed partnerships, has addressed more than a hundred years of logging, agricultural, and industrial impacts. Streambank stabilization ran from 2015 to 2024, native fish restocking from 2017 to 2024, nutrient-reduction strategy implementation from 2018 to 2024, and broader water-quality improvements from 2020 to 2024. The Bighorn today is designated a Water Trail managed by the Bureau of Land Management, its cold tailwaters and red-rock canyon drawing anglers and boaters to a landscape where the slow patience of moving water remains entwined with the human hand that reshaped it.