Solving an Amazon Mystery

In today’s high-tech world of satellite imagery and global travel, geographers would seemingly have few secrets left to unravel. But at least one question has been nagging at explorers and map makers alike: the precise source of the Amazon, the world’s largest river, with six times the flow of the Nile.

Since at least 1971, explorers have been bickering over which of two small streams in the Peruvian Andes actually represents the headwaters of the mighty South American river. The difference in length between the two streams is less than half a mile and the choice between the two has no practical significance whatsoever.

But the efforts involved in choosing between the two illuminate the lengths to which men and women will go to be the first and the most accurate in exploring the far reaches of the planet. A team of 22 people--led by a pair of Polish explorers--spent two weeks in the thin, frigid air of an Andes winter last July to settle the question once and for all.

Their conclusion: A stream on the 18,363-foot mountain known as Nevado Mismi is the farthest tributary from the mouth of the Amazon, 3,900 miles away in Brazil.

“I’m not saying that we have done something brand new, that we have discovered something,” said Andrew Pietowski, a 46-year-old middle school math teacher from Carmel, N.Y., who led the expedition. “But more than one person has told me that they never imagined that making a map could be such a fascinating task.”

“Knowing where the start of the Amazon is doesn’t make a change in anybody’s life,” said Piotr Chmielinski, an indoor air pollution expert from Reston, Va., who was co-leader. “But it was important for us. And now, on a map, you have a point where the river starts.”

Pietowski and Chmielinski were among a group of nine university students who left Poland in 1979 with 20 homemade kayaks, a year’s supply of kielbasa and dreams of navigating white-water rivers throughout the Americas.

But things did not go well for them. Their first attempt was on the Pescados River in Mexico. They put seven kayaks in the river and, within 15 minutes, lost six of them.

In 1981, while in Lima, they led a march against the Polish Embassy after the Polish government banned the labor organization Solidarity. After that, the Polish government didn’t allow them to return home for years.

Eventually, their skills improved and members of the group ran white water in more than 20 rivers in 11 countries. Chmielinski was the first to kayak the waters of Colca Canyon in Peru, which is twice as deep as the Grand Canyon. Pietowski was the first to kayak the entire length of the Amazon.

But the question of the river’s origin kept nagging at them. Then, on May 2, Pietowski got a memorable e-mail message from Andrew Johnston of the Smithsonian Institution. The U.S. Defense Department, Johnston said, had stopped blurring the signals from its Global Positioning System satellites, thereby sharpening the accuracy of hand-held GPS units from 10 meters to 1 meter. The signals were originally kept to low resolution to prevent enemy powers from using the satellites to target U.S. facilities.

Now, Johnston said, the satellite measurements were accurate enough to enable the GPS units to pinpoint the source of the Amazon.

Immediately, the kayaking researchers began organizing an expedition of 22 people with support from the National Geographic Society and Chmielinski’s company, HP Environmental, among others, to take advantage of the high resolution now available with GPS units.

“We needed a big team because the Apurimac, the Amazon’s longest tributary, begins in five valleys, with five creeks coming down,” Pietowski said. With 22 people, they could explore all five simultaneously.

That was important, he added, because exploring at that altitude and in those temperatures is hard work. “After two days of walking, you would have to take a day off and rest,” he said. “Listening now to audiotapes we made during the trip, I can tell how fatigued we actually were.”

The team gathered in Arequipa, the nearest large city, where members spent a week mountain biking to get used to the altitude. A drive of 1 1/2 days and a day’s climb brought them to their base camp at 15,000 feet, where the five creeks come together, and where they spent more time getting acclimated.

“The lack of oxygen in the air is the biggest difficulty,” Johnston said. “People lose their appetites, get nauseous, develop headaches, have trouble sleeping.” Because they were in the middle of winter in the Southern Hemisphere--a time chosen because it is the dry season in the region--the temperature at night dropped to zero inside the tents. “But we got some snow, anyway,” he added.

“When people hear Amazon, they think rain forest,” Johnston noted. “But at the source, there are no trees, just dirt and rocks. It’s cold, high and dry. There’s a little grass, but not much. It’s not what people think of, that’s for sure.”

Three of the group had to go back to lower altitudes because of oxygen deprivation, while a fourth returned after eating something that made him extremely ill.

Johnston established a base at the convergence of the creeks with one GPS unit. Teams took other units and spent eight days mapping the course of the creeks. Each team would stop every 50 yards or so and take an accurate measurement of its position. Their data, totaling more than 40,000 observations, were fed into Johnston’s laptop when they returned to base.

Finally, on the eighth day, “there were 15 people squeezed into a big dome tent, the biggest on the market,” Pietowski said. “It was cold. The sun was going down and there was a vicious wind, chilling us to the bone. Suddenly, the computer was plotting [all the data] onto a map. We just started screaming, there was such emotion.”

The selection had come down to two creeks, Mismi and another. The data showed that water flowed a few hundred yards farther in Mismi, making it the source of the Amazon. In summer, the second creek is actually somewhat longer. But, they decided, by definition, the source should be the point furthest from the mouth where water flows continuously.

“By the peak of [Nevado] Mismi, I could feel the hunger, feel the cold, feel my face bitten by the sun, even with creams,” Pietowski said. “These are human feelings, and here we were supported by human technology--a connection of two worlds, the natural world and the technological. And the product was a map.”

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Maugh can be reached at thomas.maugh@latimes.com