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Topic
- Flood control 29
- Dams 28
- Rivers--Oregon 28
- Fishes--Conservation 12
- Salmon 11
- Irrigation 5
- Lectures and lecturing 3
- Water--Pollution 3
- Inland water transportation 2
- Oregon Audubon Society 2
- Pacific College (Newberg, Or.) 2
- Birdhouses 1
- Izaak Walton League of America 1
- Migratory birds 1
- Sewage disposal plants 1
- Water conservation 1
- Waterfowl 1