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Topic
- Rivers--Oregon 219
- Dams 126
- Fishways 34
- Salmon 30
- Flood control 28
- Canals 16
- Fishes--Conservation 16
- Water--Pollution 15
- Hydroelectric power plants 13
- Power-plants 9
- Sawmills 8
- Waterfalls 8
- Fish hatcheries 7
- Lumber trade 6
- Lectures and lecturing 5
- Rapids 5
- Salmon--Artificial spawning 5
- Sewage disposal plants 5
- Bridges 4
- Fish screens 4