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Topic
- Birds--Conservation 6
- Rivers--Oregon 6
- Wildlife refuges 5
- Lectures and lecturing 3
- Salmon 3
- Water--Pollution 3
- Dams 2
- Izaak Walton League of America 2
- Dams--Design and construction 1
- Fishes--Conservation 1
- Forests and forestry 1
- Parks 1
- Wildlife conservation 1