CADIZ, Calif. — Gazing out of a turboprop high above his company’s main asset — 34,000 acres in the Mojave Desert with billions of gallons of fresh water locked deep below the sagebrush-dotted land — Scott Slater paints a lush picture that has enticed a hardy band of investors for a quarter-century.

Yes, Mr. Slater admits, his company, Cadiz, has never earned a dime from water. And he freely concedes it will take at least another $200 million to dig dozens of wells, filter the water and then move it 43 miles across the desert through a new pipeline before thirsty Southern Californians can drink a drop.

But tapping cash, as opposed to actual water, has never been a problem for Cadiz. “I think there’s plenty of money out there,” Mr. Slater said.