Trouble Ahead for the Canal?

By John Borrell/Panama City

Seventy-three years after it opened to link the Atlantic and Pacific oceans, the Panama Canal remains one of the engineering marvels of the world. At one end of the 50-mile-long waterway, the 12,000 ships that traverse it annually are lifted 85 ft. above sea level by a series of locks, enabling them to sail through the mountainous spine of the Panama Isthmus. When they reach the opposite coast, another set of locks floats them gently back down to the ocean.

The operation of these aquatic elevators consumes a prodigious amount of fresh water. Each time a ship passes through the canal, some 52 million gallons must be pumped into the locks and then, after the ship has passed, flushed out to sea. "The locks are like giant water closets," explains an official of the Panama Canal Commission. "Once you pull the chain, you never see the water again."

For years the source of that water seemed inexhaustible. Much of it comes + from 165-sq.-mi., dam-created Gatun Lake, through which the ships pass on their route across the isthmus. Most of the remainder is tapped from nearby Madden Lake, formed in 1935 (also by damming) to provide an additional reservoir of water for the dry season. But now a 375-page report by Stanley Heckadon Moreno, an environmentalist at Panama's Ministry of Planning, has raised a startling worry about the canal's future: it may be running short of water.

One problem is that the dense tropical rain forest that blanketed the 1,300-sq.-mi. watershed around the route of the canal has been disappearing at an alarming pace, cut away by farmers. By 1950 some 20% of the forest had been cut. Now more than 70% has vanished, and about 800 acres of the remainder is being cleared every year.

Once the trees are gone, denuded slopes are eroded by rainfall, which has been washing soil into 20-sq.-mi. Madden Lake at the rate of half a million tons a year. A study by Hydrologist Luis Alvarado of the Panama Canal Commission shows that silt accumulating at the bottom of the lake has reduced its storage capacity by 5%. By the year 2000 the loss could be as high as 10%, and by 2020 nearly 20%.

The threat to the canal may be worsened by another consequence of deforestation. According to Donald Windsor of the Smithsonian Tropical Research Institute, the average annual rainfall in central Panama has decreased by as much as 10% since the turn of the century. "Because of deforestation," he says, "there is less evapotranspiration." And because less water rises into the air in vapor form, less returns in the form of rainfall.

Despite these dire projections, the Panama Canal Commission has reacted coolly. Says David Baerg, the group's environmental and energy-control officer: "We are not in a crisis situation, where things have to be changed immediately." Heckadon disagrees. He has called for the formation of a body like the Tennessee Valley Authority to take charge of the watershed and begin enforcing conservation of the remaining rain forest. "If we don't start acting now," he says, "in 15 years or so we might start having problems."