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- Reclamation of land--United States18
- Pollution11
- Coal mines and mining9
- Strip mining9
- Acid rain6
- Coal5
- Radioactive wastes4
- Environmental law--United States3
- Environmental protection3
- Wild and scenic rivers3
- 4-H clubs2
- Carbon tetrachloride2
- Water conservation2
- Cancer1
- Disaster relief1
- Education1
- Factory and trade waste1
- Flood damage1
- Geology1
- Gold mines and mining1
