Fish Ladder at Bonneville Dam

Migrating fish are attracted to large flows of water coming from the Bonneville Dam. To take advantage of this natural reaction, fish-collection facilities are placed along the face of the powerhouse and at each end of the spillway dam. These collection facilities attract fish with their own flow of water, which leads fish into the fishways.
The Bradford Island fishway is a long, inclined flume with horizontal weirs creating a series of successive pools. Each pool is one foot higher than the adjacent pool downstream. Fish may swim through submerged artifices or over the wier crests to move from one pool to the next higher one.
The upper portion of the Bradford Island fishway was recently reconstructed. Instead of the weirs found in the lower reaches of the fishway, the new design creates and inclined series of vertical slots and eddy-lice pools. Biological research has shown that these inclined pools are superior for fish passage and allow for self-regulating control of water in the fishway.
As they near the top of the fishway, the fish pass the counting station and move by the winding windows. You are invited to watch the underwater viewing area located on level 1 (down the stairs).

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