Lochsa River

About

Lochsa River, Idaho — 1805 Lewis & Clark Lolo Trail. Long before any American or European expedition arrived, the Lochsa corridor flowed through the ancestral territory of Indigenous peoples, serving as a primary travel corridor, hunting ground, and gathering place. The trail system along the river that Lewis and Clark would later follow was already worn into the mountains by generations of movement across the Bitterroot range. That deeper history sits beneath every later chapter — the treaties of the 1800s, the 1830 Indian Removal Act, and the allotment era that stretched from the 1840s into the 1890s established the cession framework that reshaped the region.

In 1805, the Lewis and Clark expedition descended the Lolo Trail through the Lochsa corridor, completing the first recorded U.S. overland crossing of the northern Rockies; they returned the same way in 1806. It stands as the first U.S. exploration of the drainage. In 1809, David Thompson reached the Lochsa's headwaters and established the first trading post in the watershed — the region's first European settlement. The 1805–1806 route is now part of the Lewis and Clark National Historic Trail, and the Lochsa corridor runs through it.

Between 1880 and 1920, the Lochsa's watershed gave up its old-growth white pine, cedar, and fir to decades of commercial logging. Logging drives moved timber downstream, local sawmills processed it for a regional timber industry and the era's railroad expansion, and by 1910 the old-growth stands were largely exhausted. State forestry conservation began in 1915, and the establishment of state forests in the 1930s ended large-scale cutting. The hydrological record took shape in the same window: USGS gauging stations went in between the 1880s and 1910s, laying the foundation for the record that now runs under station 13337000 and shows an average flow of 2,200 CFS.

The construction of three Hells Canyon dams on the Snake River between 1955 and 1967 was the watershed's most consequential modern disruption, blocking the anadromous runs of steelhead and salmon that had historically moved through the Clearwater basin. Recovery has been slow and legally scaffolded. The 1968 Wild and Scenic designation covered both the Lochsa and the Selway, and the 1980 designation of the Frank Church–River of No Return Wilderness protects 30 miles of the river. Since 2010, the Lochsa Conservation effort — carried by the regional DNR and local watershed partnerships — has brought 99 percent of the watershed under protection from development, with streambank stabilization, native fish restocking, nutrient reduction, and water-quality improvements following through 2024. The Lochsa remains a premier steelhead, salmon, and trout fishery and one of the cleanest large rivers in the United States.

Paddlers meet this history on continuous, heart-pounding whitewater. The Lochsa averages 2,200 CFS, with an optimal window between 1,500 and 5,000 CFS, and it divides into three distinct sections. The Upper Lochsa runs Class III–IV from Milepost 115 to 109, a warm-up stretch. The Middle Lochsa, from Milepost 109 to 90, holds the best whitewater on the river — Class III–V water building toward the Whirlwind rapids. Below that, the Lower Lochsa carries a continuous Class III runout from Milepost 90 down to Milepost 66, where the corridor eases toward Lowell.