Pend Oreille River 1920s, there was a proposal to divert the Pend Oreille through a gravity canal to irrigate the Grand Coulee and surrounding lands in eastern Washington as part of the tentative Columbia Basin Project. These plans were later dropped with the construction of Grand Coulee Dam and a pumping plant on the Columbia River. Variant names, according to the USGS, include: Bitter Root River, Bitterroot River, Clark Fork, Clarke Fork, Clarkes Fork, Clarks Fork, Deer Lodge River, Hell Gate River, Missoula River, Pend d'Oreille River, Silver Bow River, Clark's Fork, and Pend-d'Oreille River. Pend Oreille River The Pend Oreille River (
Columbia River known as the Grand Coulee. After the floods, the river found its present course, and the Grand Coulee was left dry. The construction of the Grand Coulee Dam in the mid-20th century impounded the river, forming Lake Roosevelt, from which water was pumped into the dry coulee, forming the reservoir of Banks Lake. The river flows past The Gorge Amphitheatre, a prominent concert venue in the Northwest, then through Priest Rapids Dam, and then through the Hanford Nuclear Reservation. Entirely within the reservation is Hanford Reach, the only US stretch of the river that is completely free-flowing, unimpeded by dams