Since Roman times, bathers have come to the site of a calcium-rich spring here in central Turkey to marvel at the lily-white cliffs formed as it cascaded along a hillside, and to receive a healthy, high- temperature dousing in water with a mineral count that reads like a high school science quiz.

In later times, said Deputy Undersecretary of Culture Tekin Aybash, visitors were apt to chisel off a piece of the cliffs to take home as a souvenir, and to leave a little too much of themselves behind, dirtying the water that stained the cliffs an unsightly gray.

Pamukkale may have been strictly high-toned when it was run as a health spa by King Eumenes II in 200 B.C.; now the barbarians are at the gate, in the form of European, Asian and American tourists who are flocking to some of Turkey's once-isolated regions.

"Everybody has done their best to destroy it," said Aybash, who counts himself among the perpetrators who chipped away chunks of the Pamukkale cliffs.

"The traffic has been tremendous and you cannot protect" the site, he said, with tens of thousands of people a year rinsing themselves in the travertine ponds formed as calcium accretes along the cliffside, or swimming in hotel pools that drain onto the cliffs.

After several years of delay, Aybash is overseeing plans to shoo tourists away from the popular peak of Pamukkale and down to the bottom, where he hopes they'll be content to snap photos and wade into a few man-made basins which, safely below the calcium formation, would not drain onto it and cause discoloration.

It is either that, he said, or watch Turkey's "cotton castle" turn the color of bath water.

"Any dirt that passes over the cliffs stops there and is captured" in the calcium, he said. "They would be ruined. . . .The idea is that they are to be 100 percent natural."

It is the same predicament faced by other popular Middle East tourist sites. If terrorists or political troubles drive people away, it hurts the economy. But when foreigners feel confident and arrive in droves, it puts pressure on delicate antiquities and natural features alike.

Egypt, for example, has had to restrict the amount of time visitors can spend at some ancient tomb sites because the water vapor produced by human respiration can harm the interiors.

In Turkey over the past decade, crowds that once stuck to Istanbul are now inundating beachfront towns along the Aegean Sea, and using the country's improved road network to make side trips to places like Pamukkale.

Casual about many of its ancient sites -- visitors are usually free to tromp around the ruins of Greek cities like Ephesus, for example -- Turkey increasingly has begun weighing the economic interests of tourism against the damage done by 8 million visitors a year, one Western diplomat said.

The ability of small beachfront towns like Bodrum to handle the crowds is stretched thin, while other sites, like Pamukkale, are more directly threatened.

The site of a spa in Roman and Byzantine times, the Pamukkale area remained popular among locals into modern times. Two hotels were built at the top of the cliffs with pools filled from the underground stream whose high calcium content created the unusual geological formation.

However, as Turkey became a more popular tourist destination, the effect on Pamukkale became obvious: Gray splotches began staining the calcium deposits.

At the same time, developers began tapping the mineral stream to feed their thermal pools and spas in the nearby village of Karahayit, a fact that threatened to damage the cliffs irreparably by reducing the flow of water that sustains them.

Urged by United Nations and World Bank planners to focus on preservation instead of short-term profits, Turkey agreed to buy out and tear down the clifftop hotels, and has also imposed development restrictions on Karahayit to ensure that no more than one-fourth of the underground stream is diverted to local hotels.

The cliffs have already been closed to visitors except for one narrow path; the hotels at the top will be closed after the summer season ends.

The changes will force Turkey to do some new marketing. Posters promoting the country as a tourist destination carry pictures of sunbathers lounging in Pamukkale's pools -- an activity no longer allowed.

Even so, said a diplomat familiar with Turkey's plans in the area, there is a recognition that the country's success at attracting visitors is not cost-free.

"In general, the impression is that they are aware they got away with stuff," he said, "and the party is over."

CAPTION: The spring flowing over Pamukkale's white cliffs is closed to bathers because their dips were graying the cliffs.