Possible Clues:

• Rich source of oil, also buried diamonds
• Flush out with old towel
• Prospering, though there's trouble with water supply
• Fairly rich, prosperous
• Being rich, we shall have to join the party
• Rich source and a bit of bother
• Flush job for the water wengineer?
• It takes a waterholeto be sunk in no poor way
• 'Prosperous, wealthy (4-2-2)'
• Rolling news -- essentially old lot gets recycled