Complex sentence: The two forks merge at Banks, elevation 2790 ft (850 m), forming the main Payette River, which flows south to Horseshoe Bend, then west into Black Canyon Reservoir past Emmett and Payette, emptying into the Snake River at the Oregon border.
Split into simpler sentences: The two forks merge at Banks, elevation 2790 ft (850 m), forming the main Payette River, which flows south to Horseshoe Bend, then west into Black Canyon Reservoir. Below the dam the river flows past Emmett and Payette, then empties into the Snake River at the Oregon border.