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- Agriculture 1
- Aquifers 1
- Bureaucracy 4
- Burning of land 1
- Conservation of natural resources 1
- Conservation of natural resources--Law and legislation 1
- Deserts 1
- Economics 1
- Finance 4
- Food and Agriculture Organization of the United Nations 1
- Forests and forestry 1
- Game and game-birds 1
- Geological Survey (U.S.) 11
- Groundwater 6
- Hydrogeology 1
- Hydrology 7
- Irrigation 1
- Izaak Walton League of America 1
- Lakes 1
- Lakes--Oregon 1
