The 2nd Power Station at Bonneville Lock and Dam. Bonneville Dam consists of several structures that together complete a span of the Columbia River on the Oregon/Washington border 146 miles from the Pacific Ocean. The facility's primary functions are electrical power generation and river navigation. The first powerhouse was built in with 10 generators and has a capacity of 526 megawatts. The second powerhouse was built with 8 generators (plus 2 at the fish ladders) which have a capacity of 558 megawatts. The dam was declared a National Historic Landmark in 1987. Image 1 of 2.