Mornos artificial lake, located around 150 kilometers northeast of Athens, has served as a key reservoir for the Greek capital's water supply for decades.

When a dam was constructed on the Mornos River in 1979 to create the lake, the village of Kallio had to be evacuated and submerged under water. But this summer Kallio has risen from the depths, becoming partly visible again as the water level has dropped.

In July 2023, the surface area of the lake was around 16.6 square kilometers, according to data released by the National Observatory of Athens. However, this July it was just 12.8 square kilometers.

Equally disheartening figures have been reported for water resources across Greece, with several islands already facing water shortages. However, the problem is also looming on the horizon in other regions due to prolonged drought and decreased rainfall and snowfall.

The Environment and Energy Ministry announced on Tuesday that in the last two years, the water reserves at Mornos and the other three main reservoirs for the greater Athens area have declined by some 30 percent to about 703 million cubic meters.

With half of the country's population living in the greater Athens area, the figure is worrying.

"There was low rainfall, and in particular snowfall, during the winters of 2022-2023 and 2023-2024," Dimitrios Emmanouloudis, professor of Mountain Water Management at the Democritus University of Thrace in northern Greece, said on Tuesday.

Snowfall helps create underground water reserves, which can be used during the summer, he said.

Since March this year, Greece has also experienced unusually high temperatures, which have increased water demand, the expert added.

The problem was exacerbated by a rapid increase in tourism arrivals in recent years. According to official statistics, the country of some 10 million people receives over 30 million visitors each year, he said. The pressure on water resources in popular tourism destinations is no longer sustainable, Emmanouloudis underlined.

In the Greek capital, which receives more visitors than other areas, the state-run Athens Water Supply and Sewerage Company (EYDAP S.A.) has activated additional water sources to support the network. These include Lake Yliki, an hour's drive northeast of Athens.

Officials said that in the worst-case scenario, if the lack of adequate rainfall and snowfall continues due to climate change, Athens' water reserves will reach the red zone within four years.

"We are maybe reaching the yellow zone, but there is no way the capital will be left without water," Emmanouloudis said. Meteorologists forecast a return to normal weather patterns in the coming months, with increased rainfall expected this autumn and winter, he added.

A government road map to address the challenge foresees investment in more infrastructure to tackle leakages and save water, the construction of more desalination plants, and better management of recycled water for agriculture irrigation.

For now, officials are advising people to save water. However, restrictive measures on consumption have not been imposed as in the early 90s, when Greece faced a prolonged drought.

"Approximately once in a decade, the lake (Mornos) goes through such a phase. The worst crisis was in 1993," Kostantinos Koutsoumbas, deputy mayor of the municipality of Dorida (which includes Mornos), said on Wednesday.

Currently, the water level has dropped by some 40 meters. However, the mayor said he worried more about the future than about the present due to the climate change's impact.

The key word is conservation, meaning better management of water resources as demand increases, Emmanouloudis said. "We must develop a culture of water conservation on an individual basis and ask tourists to act likewise."

"As consumers, we should also realize that there is a problem and we should consume water wisely. We have a share of the responsibility," Koutsoumbas said.