From Portland Hikers Field Guide
Bonneville Dam is one of the oldest dams on the Columbia, constructed between 1933 and 1937. The second powerhouse was added in 1982. The dam is somewhat unusual because it is made up of several dams on separate river channels with islands in between. From the north, the first channel is blocked by the new 1982 powerhouse. Next comes Cascades Island, then the second channel, dammed by the spillway, which regulates the water level in the reservoir. Bradford Island comes next, followed by the south channel, dammed by the original 1937 powerhouse and Robins Island. The final channel is the new lock, built in 1993. Only Bradford Island is natural; the others were created when new river channels were created.
Bonneville Dam is in the middle of a very historic area. There's a rich history here of natural landslides, Indian villages, river rapids, portage railroads and abandoned highways. Some historic sites remain accessible below the dam, others are underwater above the Dam.
From USGS (link below): Bradford Island was once an old Indian burial ground in the middle of the Columbia River. The island now is part of the Bonneville Dam structure. Lewis and Clark called the island "Brant Island", and was so named because of the large flocks of Lesser Canadian Geese observed in the vicinity... (See a 1928 aerial photo of the pre-dam Branford Island)
There is a visitor's center which makes a great location for families and school field trips. Here you can view the fish ladders that allow salmon and other species to return upstream to spawn. There is an underground viewing area with windows to give you a better view of the fish passing by (photo). Volunteers here are charged with counting every fish that passes by the window, by species!
There are plenty of interpretive dioramas, maps, and a movie to interest children of all ages (photo).
Since 9-11, the powerhouse is closed to the public except for a few guided tours a day. Call ahead for times and availability.
Any trip to the dam should include the nearby Fish Hatchery. There are dozens of holding tanks spanning across beautifully manicured lawns and landscaping. It's a pretty spot for a picnic. Children will love the tank holding two (very large!) sturgeon.
If you come in early fall, you can see salmon returning up nearby Tanner Creek into the the holding bins.
- Search Trip Reports for Bonneville Dam
Related Discussions / Q&A
- Search Trail Q&A for Bonneville Dam
Guidebooks that cover this destination
- USGS: History of Columbia River Gorge - Bonneville Vicinity
- Lewis and Clark's Columbia River: Bonneville Dam
- Bonneville Salmon Education Center on inforain.com
- FDR's Bonneville Dam Address - September 28, 1937