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Topic
- Agriculture 20
- Wildlife refuges 9
- Hunting 6
- Lakes--Oregon 5
- Rivers--Oregon 4
- Waterfowl 4
- Birds--Conservation 3
- Forests and forestry 3
- Lakes--California 3
- United States. Bureau of Biological Survey 3
- Water--Pollution 3
- Burning of land 2
- Carp 2
- Izaak Walton League of America 2
- Land use--Planning 2
- Lectures and lecturing 2
- Mountains--Oregon 2
- Oregon State Planning Board 2
- Oregon. Advisory Research Council 2
- Soil erosion 2
