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Topic
- Lectures and lecturing 11
- Rivers--Oregon 11
- Dams 5
- Salmon 4
- Sewage disposal plants 3
- Water--Pollution 3
- Birds--Conservation 2
- Killer whale 2
- Wildlife refuges 2
- Beavers 1
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Region
- Columbia River >> Clatsop County >> Oregon >> United States 11
- Portland >> Washington County >> Oregon >> United States 3
- Malheur National Wildlife Refuge >> Harney County >> Oregon >> United States 2
- Blitzen Valley >> Harney County >> Oregon >> United States 1
- Lower Klamath National Wildlife Refuge >> Siskiyou County >> California >> United States 1
- Willamette River >> Multnomah County >> Oregon >> United States 1
Decade
- 1930-1939 11
