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Topic
- Rivers--Oregon 77
- Dams 47
- Flood control 29
- Mountains--Oregon 21
- Fishes--Conservation 20
- Salmon 18
- Lakes--Oregon 15
- Irrigation 14
- Lectures and lecturing 14
- Forests and forestry 13
- Water--Pollution 13
- Wildfires 12
- Oregon Wildlife Federation 11
- Birds--Nests 10
- National parks and reserves 10
- Roads 10
- Water-supply 10
- Tillamook Burn, Or., 1933 9
- Universities and colleges--Faculty 9
- Cutover lands 8