- (FORTUNE Small Business) – Boone Pickens slips off his bright-orange necktie (he's a proud son of Oklahoma State; the football stadium in Stillwater bears his name), pops open a can of Dr Pepper, eyes my tape recorder suspiciously, and says, "Let me look at what you're going to print. I don't care what you've written, but I do care about what I've said. Let me look at it so I don't come off as, you know, some dumb ass."

Okay, I'll verify the quotes for accuracy, but honestly, Boone Pickens a dumb ass? We're talking about the quintessential Texas wildcatter turned corporate raider turned fabulously wealthy hedge fund manager. Pickens was given up for gone when energy prices collapsed in the mid-1990s but at 77 is making more money -- lots more -- than ever. His various BP Capital Funds, with headquarters in a brick and glass midrise in Dallas, have soared lately on energy futures, accumulating more than $3 billion in assets. Last year, deep into a career that spans half a century, Pickens finally cracked the Forbes 400 list of richest Americans, with a net worth estimated at $750 million. He then doubled his pile in 12 months. Pickens used to joke that his IQ moved up and down with the price of gas; at $3 a gallon, he's a genius.

Starting in his 20s with zero reserves and a $2,500 stake, he founded Mesa Petroleum and went on to produce three trillion cubic feet of natural gas and 150 million barrels of oil. In his 50s he attempted hostile takeovers of Cities Service, Gulf, Phillips, and Unocal, none of which succeeded. But Pickens made huge profits anyway by driving up the value of his stakes in those companies and became, Fortune once wrote, "the most hated man in corporate America." His latest scheme: water rights. Already looking beyond oil and gas, he's diversifying. He has secured the rights to 200,000 acre-feet of groundwater centered on Roberts County (pop. 863) in the Texas Panhandle.

Pickens got serious about water in 1997 after the local Canadian River Municipal Water Authority (CRMWA), serving nearby Amarillo and Lubbock, refused Pickens's offer to sell it the water under his ranch. Pickens was going through an expensive divorce at the time and "really needed the money," he says. Now that he has more money than he will ever need, he seems to be motivated by revenge.

"They were really rude," Pickens says, still miffed, as he stands before a large, multicolored map on the wall of his office at BP Capital--blue for his holdings, green for CRMWA. "They just said, 'Aaaaah, we're not interested. When we want more water, we'll call you -- you don't need to call us.'" Since then he has invested some $40 million (paying as much as $500 an acre, an unheard-of price in the panhandle) and says he'll export his water through a proposed billion-dollar pipeline to distant, thirsty cities, possibly the Dallas-Fort Worth Metroplex or San Antonio, where the stuff could conceivably bring $1,200 per acre-foot. "All I need is a buyer," he says.

In any case, Pickens promises that he will donate all his eventual water profits to charity. Which is another way of saying that his estate will go to charity. "I won't see the whole story," he admits, "but I will be here to see water sold and the infrastructure built and the water delivered. I think that will happen in less than ten years."

If he finds a buyer, that is, and if he secures financing for the pipeline. Two big ifs. But then, what kind of dumb ass would bet against Pickens?