The Bonneville Dam (541/374-8820, www.nwp.usace.army.mil/op/b/home.asp ) can be reached via Exit 40 off I-84. The signs lead you under the interstate through a tunnel to the site of the complex, Bradford Island. En route to the visitor center you drive over a retractable bridge above the modern shipping locks. On the other side are the powerhouse and turbine room.
Downriver on the Washington side is the second-largest exposed monolith in the world (Gibraltar is first). This 848-foot lava promontory abutting the shoreline is known as Beacon Rock , a moniker bestowed by Lewis and Clark.
Beyond the generating facilities is a bridge, underneath which is the fish-diversion canal. These fish-ways cause back eddies and guide the salmon, shad, steelhead, and other species past turbine blades. You’ll want to stop for a brief look at the spillways of the 500-foot-wide Bonneville Dam, especially if they’re open.
While it isn’t anywhere near the largest or the most powerful dam on the river, Bonneville Dam was one of the largest and most ambitious of the Depression-era New Deal projects. Completed in 1937, it was the first major dam on the Columbia River. The building of the dam brought Oregon  thousands of jobs on construction crews, and the cheap electricity that it produced promised future industrial employment.
President Franklin Roosevelt officiated at the dam’s opening in 1938, attended by a cheering throng of thousands. The two hydroelectric powerhouses together produce over 1 million kilowatts of power, and they back up the Columbia River for 15 miles.
At the visitors center (503/374-8820, 9 a.m.–5 p.m. daily year-round), ask the Army Corps of Engineers personnel at the reception desk about tours of the power-generating facilities and about public campgrounds , boat ramps, swimming, and picnic areas. Be aware that the dam may be closed to visits without warning due to security alerts.
The reception area has exhibits on dam operations, pioneer and navigation history on the Columbia, and fish migration. A long elevator ride takes you down to the fish-viewing windows, where the sight of lamprey eels—which accompany the mid-May and mid-September salmon runs—are particularly fascinating. Outside the facility there’s access to an overlook above the fish ladders. A walkway back to the parking lot is decorated with gorgeous roses spring–fall.
Retrace your route back to the mainland from Bradford Island and turn right, following the signs to the fish hatchery (7:30 a.m.–5 p.m. daily, free). Visit during spawning season (May and Sept.) to see the salmon make their way upriver. During spawning season, head to the west end of the hatchery, where steps lead down to a series of canals and holding pens. So great is the zeal of these fish to spawn that they occasionally leap more than three feet out of the water.
Inside the building, you can see the beginnings of a process that produces the largest number of salmon fry in the state. Fish culturists sort the fish and extract the bright-red salmon roe from the females. These eggs are taken to the windowed incubation building, where you can view trays holding millions of eggs that will eventually hatch into salmon.
Once these fry grow into fingerlings, they are moved to outdoor pools where they live until being released into the Columbia River by way of the Tanner Creek canal. The whole process is annotated by placards above the windows inside the incubation building.
The salmon and trout ponds and the floral displays are worth your attention at certain times of the year, but the sturgeon pools to the rear of the visitors center are always something to see. Bonneville is the nation’s only white sturgeon hatchery, and the government has made this facility user-friendly. Biologists claim that the Columbia River white sturgeon, with bony plates instead of scales, has remained unchanged for 200 million years.