Environment : Losing Prospects for the ‘Lost City of the Incas’ : * Tourism, time and neglect are taking a worrisome toll on Machu Picchu. But Peru says it has no means to save the archeological wonder.

Walter Huerta, a veteran shepherd of foreign tourists, pauses with his flock beside a magnificent wall of finely fitted stones. He points to places where the structure is bulging, sagging and slipping, and explains that on some chaotic days more than 1,500 tourists and Peruvian schoolchildren invade these ruins, thronging through chambers and doorways and passageways, trampling over walkways like the one along the top of the wall.

“You know what happens if you put all those people together,” tour guide Huerta comments to his charges. “Their weight can do a lot of damage. Look at this wall--the wall is crumbling. That’s a consequence of all those people.”

Tourism, time and neglect are taking an increasingly worrisome toll on the citadel of Machu Picchu, one of the New World’s greatest archeological treasures. And it’s not only the famous “Lost City of the Incas” that is being degraded and damaged. A spectacularly beautiful natural park surrounding the ruins and containing many other wonders of Incan architecture is also deteriorating.

The main ruins perch at 8,000 feet above sea level in a natural saddle between one steep, jagged peak named Machu Picchu, or “old mountain,” and another named Huayna Picchu, “young mountain.” Other peaks stand sentinel like an extended family of craggy green giants, all watched from on high by the snow-capped demigods of soaring Andean summits.

Runoff from the eternal snows roils through a winding gorge almost straight below the ruins, 1,500 feet down. It is the Urubamba River, a headwater of the mighty Amazon.

The Machu Picchu Historical Sanctuary covers 125 square miles of this majestic setting, but despite its name, little is being done to preserve the natural environment.

To begin with, the park is inhabited by more than 2,000 people, up from 1,200 in 1972, and their environmental impact is virtually uncontrolled. Aside from those assigned to the ruins, there are no forest or park rangers.

A town of 1,200 residents called Aguas Calientes has grown rapidly as merchants and vendors have come to make a living from the tourist trade. The growth has been haphazard; much of it is cheap, makeshift construction, with poor public services and little planning.

Peasant farmers are scattered through much of the park, and their activities cause more widespread damage. Their cattle, sheep and goats graze freely through the park, devouring the native vegetation. Their slash-and-burn farming methods scar slopes and flats, unleashing erosion, destroying more natural plant life, sometimes sparking forest fires. In 1988, a fire blackened nearly 10,000 acres of timberland here.

The peasants also cut native trees for fuel and building materials, often replanting not with native vegetation but with intrusive species such as eucalyptus and pine. They hunt native fauna such as the Andean condor, deer, puma, a small bear called oso de anteojos and a wolf called lobo de rio.

Thousands of tourists trekking through the park each year, especially along 25 miles of the old Inca Trail leading to the main ruins, have added to the damage. Although hikers and campers usually are accompanied by privately employed guides, the traffic has inevitably brought deterioration of the partially stone trail and major ruins along the way. Tourists sometimes remove orchids and other plants.

Blue-uniformed guards watch over the main ruins, blowing whistles when they see tourists climbing on structures or breaking other rules. But there is damage that the guards can’t prevent. Some key examples:

* In the main temple, settling earth has caused walls to sag, creating wide separations between carved rocks that once were closely fitted. The settling, said to have been caused by poor drainage and past archeological excavations, reportedly has been stopped. But the damage hasn’t been repaired.

* Faulty drainage is also damaging the Torreon, a semicircular chamber that is one of Machu Picchu’s finest structures, and to the cave-like royal tomb below. Some rocks in the foundation are beginning to splinter under water pressure.

* Granite used to build the citadel is deteriorating. Heat, wind, water and smoke from fires in the park are slowly degrading the rock in the absence of preventive maintenance.

* Erosion has reached advanced stages along thick walls protected during Incan times by thatch roofs but now open to rainwater that leaches away dirt packing and causes stone surfaces to loosen.

* Some stone-walled agricultural terraces on a steep slope at the foot of the ruins have collapsed from lack of maintenance, and others are slowly slipping away.

* Particularly sensitive areas supposedly closed to tourists are occasionally trampled by large numbers of tourists who become frustrated by bottlenecks on the main path and venture off the designated walkways.

Peru’s National Institute of Culture is responsible for administration of the ruins. Fernando Astete, an anthropologist with the institute, said that lack of funds has forced it to reduce the number of maintenance workers at Machu Picchu from 60 to 30 in the last year. He said no major work is being done currently to stop the deterioration.

At the beginning of this year, parts of the ruins were overgrown with tall weeds because money to pay weed-cutters had run out. The weeds have since been cut back again, but maintenance funds remain inadequate.

The ruins were completely overgrown with vegetation when an Indian guide led American explorer Hiram Bingham to Machu Picchu in 1911. Bingham, who later served as governor of Connecticut and as a U.S. senator, wrote in a 1948 book titled “Lost City of the Incas” that his first view of the structures in the Torreon area “seemed like an unbelievable dream. Dimly, I began to realize that this wall and its adjoining semicircular temple over the cave were as fine as the finest stonework in the world.”

When the Spanish conquered the Incas in the 1500s, they did not discover the inaccessible citadel, so there is no written record of what exactly Machu Picchu was. But there are many theories: It may have been a holy city, a military outpost, an experimental farm, a hide-out for Inca nobility, an estate owned by a powerful lord.

Another mystery is why the Incas abandoned Machu Picchu. Did the inhabitants flee from the advancing conquistadors? Or were they decimated by European diseases that spread through Indian populations after the conquest? Tourist guide Huerta says he thinks the people of Machu Picchu may have left because their water supply was polluted.

What is certain is that the Spanish never set foot in Machu Picchu, Huerta said. “How do we know that? We have no churches, no crosses.”

After Bingham’s discovery, a sporadic trickle of visitors to Machu Picchu grew into a flood, making this one of South America’s premier tourist destinations.

In 1988, Machu Picchu’s peak year for tourism, more than 200,000 people came. But news of guerrilla warfare and a cholera epidemic in other parts of Peru sharply reduced the flow to 39,000 tourists in the first seven months of 1991. Now, there are days when fewer than a dozen visitors show up.

Conservationists say the slump in tourism has slowed damage to the ruins and the environment. But it also has cut revenues used for maintenance and conservation. The Institute of Culture charges tourists a $10 entry fee at Machu Picchu. Most of the income, however, is used to pay for other work, such as administering Inca ruins and colonial buildings in Cuzco.

Carlos Cano, a chemist and geologist with the institute, said drainage work is needed in several places to prevent further damage to important structures. Rock surfaces must be treated to prevent decomposition, and terraces have to be constantly repaired. The most urgent work would cost about $3 million, Cano estimated, adding, “We never had that much.”

“Every year, we lose a terrace if there is no maintenance,” he said. “But we have no budget; we have no equipment or anything to work with.”

Anthropologist Tania Villafuerte is coordinator of a project to draft a master plan for Machu Picchu that will include proposals for repairs and restoration. Villafuerte said the project, to be financed by the U.N. World Heritage Fund, will produce a short-term “action plan” by the end of this year for work needed most urgently.

There are several pressing needs, she said: A new traffic plan guiding tourists through the ruins along routes where damage can be avoided; studies of the population patterns and agricultural practices in the historical sanctuary; deployment of park rangers, and financing from the private tourist industry to pay for the rangers. She emphasized that supervision in the sanctuary is urgent because peasant residents and outsiders “are killing, eliminating natural species of both flora and fauna.”

Inca Rise and Ruins Inca history dates to circa 1200. Great conquests by Pachacuti; his son, Tupo Inca, and Huayna Capac expanded the empire to 2,000 miles. Spaniards overtook the empire in the 1530s. The relics of Machu Picchu, Chan Chan and Nazca are monuments to the ancient empire. Pachacuti: 1438-1463

Pachacuti and Tupo Inca: 1463-1471, Tupo Inca: 1471-1493

Huayna Capac: 1493-1525