Possible Clues:

• It's east of Israel
• *Lowest point on the earth's surface
• Bill's in river, a very low stretch of water
• Salty lake on the Israel/Jordan border
• Dad swimming with ease? He wouldn't be, in this lake!
• Notices planted in river area and lake
• The lake is a late ocean
• Highly salty body
• These days needing backing to keep daughter in comfort in depressed area
• Saltwater lake in the Jordan valley