The Allianoi archaeological site could soon be under water if authorities carry out their plans to flood a newly constructed reservoir. Located in western Turkey, the site is a well-preserved example of an ancient Roman health spa.

Archaeologist Ahmet Yaras, head of the Allianoi excavation team, is spearheading a campaign to save the site from being submerged. They are trying to rally international support to pressure the authorities to move the reservoir — or at least delay the flooding for another five years so that they can finish the excavations.

Allianoi is a hot-springs area 18 kilometres northeast of the ruins of ancient Pergamon that was used as a spa in Hellenistic times. It was constructed during major public works done under the reign of the Roman emperor Hadrian during the second century AD. In addition to the spa, the Allianoi site includes public squares, streets, gates, bridges, fountains and buildings. Together, they encompass about 50,000 square metres, and they could all end up in the middle of the reservoir.

About 20% of Allianoi has been excavated, yielding some 10,000 artifacts, including ceramics, coins, glass and statues. "Allianoi is in an absolutely astonishing state of preservation," says Felix Pirson, head of the Istanbul branch of the German Archaeological Institute (DAI). "It gives you the impression of a modern Baden-Baden."

The reservoir would be created by the 700-metre-long Yortanli Dam, part of a massive irrigation project proposed by the Turkish State Waterworks Authority (DSI) in the 1960s to provide water for more than 70 square kilometres of farmland along the Ilya River.

Construction of the dam began around 1993, and it was scheduled to start operation in 2005. But protests over Allianoi have postponed the planned flooding, says Mark Snethlage, policy and campaigns officer for Europa Nostra, the pan-European federation for cultural heritage.

Attempts to find technical solutions to save Allianoi, such as putting up a protective wall around the site or convincing the DSI to move the dam, seem to have come to an end. Snethlage says that Turkish members of the Parliamentary Assembly of the Council of Europe confirmed at a 23 January meeting that "it seems very likely that Allianoi is lost, and will soon be flooded." No official date has yet been set.

"One should not forget that a considerable amount of money has been invested in the construction of the dam," Snethlage says, "and that local farmers have been asking for the irrigation water."

In addition to support from archaeologists and preservationists around the world, Turkish activists also have the support of Olli Rehn, the European Union commissioner who oversees enlargement of the EU. The Turkish government has actively lobbied Brussels for EU membership. A spokeswoman for Rehn says that the commissioner has communicated with the Turkish authorities, "noting that that there appeared to be different technical solutions possible which would avoid the flooding of Allianoi while allowing for the irrigation project to be realized".

Archaeologists discovered Allianoi in the 19th century while documenting sites in the area. After more than a century in which little work was done, Yaras — of Trakya University in Edirne, Turkey — began the current excavations in 1998. The site's spa has marble floors and walls that still reach the ceiling.

Experts say that Allianoi is also located intriguingly close to Asklepion, an ancient medical centre named after Asklepios, the god of healing. But no one is sure of the exact connection between the two sites, says Pirson. "In this context, Allianoi is an important element," he says.