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- Locks (Hydraulic engineering) 22
- River engineering 11
- United States--Appropriations and expenditures 10
- Canals--Design and construction--Costs 7
- River surveys 7
- Northwest, Pacific 6
- Bodies of water 5
- Dams--Design and construction 5
- West (U.S.) 5
- Photography 4
- Rivers 4
- Rivers--Oregon 3
- Steamboats 3
- Cascade Range 2
- Mountains 2
- Postcards 2
- Riparian areas 2
- Barges 1
- Boats 1
- Canals 1
