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- Dams 56
- Rivers--Washington (State) 22
- Fish screens 18
- Ditches 14
- Fishways 14
- Canals 4
- Rivers--Oregon 4
- Boats 3
- Bodies of water 2
- Conservation of natural resources 2
- Irrigation canals and flumes 2
- Northwest, Pacific 2
- Spillways 2
- Agriculture 1
- Canyons 1
- Environmental impact analysis 1
- Fisheries 1
- Flood control 1
- Flumes 1
- Hydraulic engineering 1