Related Clues:

• TVA structures
• Four-footed mothers
• Water holders
• River stoppers
• Power sources
• Some four-footed parents
• Hoover and others
• Four-footed moms
• Roosevelt and Hoover
• River structures
• Some four-footed mothers
• Obstructs
• Emulates beavers
• Blocks up
• Beavers' creations