Related Clues:

• Ramjets, e.g
• Beavers build them
• They may cause course reductions?
• Beavers' projects
• Beaver-built barriers
• Gasoline, diesel, ethanol et al
• River regulators
• Creek blockers
• Lake creators
• Goes by car
• What cowlings cover
• Beaver-built blockages
• Beaver barriers
• Gasoline and coal
• Hoover and Mossyrock