Clark Fork

About

Clark Fork River, Montana Idaho — 1809 David Thompson, 2008 Milltown Dam Removal, Superfund Largest, 1880s Mining. The river's numbers tell part of the story. The Clark Fork runs 310 miles and drains 22,800 square miles of Montana and Idaho, flowing northwest to its confluence with Lake Pend Oreille in Idaho. Gauge 12340500 records an average flow around 5,400 CFS against a historic figure near 4,900, and paddlers find the sweet spot between roughly 2,000 and 10,000 CFS. The whitewater rates Class I–III, ranging from the urban float through Missoula, where Brennan's Wave draws surfers, to the 14-mile Alberton Gorge canyon at Class II–III, down to the milder Class I–II lower river between Superior and St. Regis.

Long before any of that, the Clark Fork valley was home to the Salish (Séliš) and Pend d'Oreilles peoples for thousands of years, with the Missoula valley serving as a major gathering place. Their name for the river was Nmesuletkʷ. The 1855 Hellgate Treaty forced the Salish to the Flathead Reservation, ending their occupation of the Missoula valley. Thompson's 1809 post opened the fur-trade chapter, and the knowledge he drew on likely came from the Kootenai people who had long inhabited the region.

Mining and timber then reshaped the watershed. From the 1880s through the 1940s, the Clark Fork basin was heavily logged to support the Anaconda Copper Mining Company — which operated from 1881 to 1980 and stood as the largest copper mine in the world for 90 years — and the Milwaukee Road railroad expansion of 1883–1950. The Missoula and Deer Lodge sawmills of 1890–1920, the Northern Pacific Railway's Clark Fork branch of 1907–1930, and copper smelter demand for fuel and mine timbers from 1910 through the 1940s drove the cutting. The 1860s–1890s mining era, centered on operations like the Bunker Hill Mine, left the upper Clark Fork one of the most polluted rivers in America after a century of copper mining in Butte and Anaconda.

Recovery defined the modern era. The Superfund designation of the upper Clark Fork ran from 1983 to 2008, and combined with 1990s timber sale reductions it ended the commercial logging era. The 2008 Milltown Dam removal ranked among the largest Superfund dam removals in U.S. history, and the EPA cleanup — described as the largest in the country — restored the river. Missoula's Brennan's Wave surf park now stands as a symbol of that turnaround. In 1976, the Montana Department of Fish, Wildlife and Parks and the U.S. Forest Service had studied 310 miles of the Clark Fork for Wild & Scenic designation, from its headwaters near Butte to its confluence with the Flathead River; that study recommended portions for designation but was superseded by the Superfund cleanup's focus on water quality.

Today the Clark Fork is prized as much for its waters as its history. It carries a Montana Blue-Ribbon Trout Stream designation on its lower reach and anchors the Alberton Gorge Recreation Corridor. Rainbow, cutthroat, and brown trout draw both bait and fly anglers to its currents, and the Clark Fork Coalition's 2020–2024 monitoring program continues to document the river's recovery. From a fur-trade outpost to a celebrated trout fishery, the river remains a defining artery of western Montana's landscape and livelihood, supporting the Missoula and Butte economies along its northwestern run toward the Pacific watershed.