You sure you weren't sold some swampland that you convinced yourself is worth something?
Sure it was a real river?
During the Twenties, real estate operators brought trainloads of prospects down to the Valley and let them pick grapefruit right off the trees and eat it. One of these pioneer promoters is said to have constructed a large artificial lake and sold plots all around it. "The lake will sub-irrigate your groves." As soon as the last sale closed, he turned off the water and disappeared with his lake, leaving the prospects sitting there in a desert.
How do you know it was "insider information" and not just a smooth operator telling marks what they want to hear.