The Mornos reservoir, a key water source for Athens, has shrunk to its smallest September size since 2014, the National Observatory of Athens said Friday.

On September 9, the reservoir’s surface area measured 8.9 square kilometers – 58% of the decade’s average – compared with 11.4 sq.m. in 2024 and 15.3 sq.m. in 2023, according to meteorologist Kostas Lagouvardos, head of Meteo.gr.

Water volume fell to 193 million cubic meters on September 11, down 41% from last year and the lowest since a 1993 drought.

Lagouvardos cited declining rainfall and snowfall. From January to September 11, only 298.4 millimeters of rain were recorded at the Mornos dam, compared with a 2015-24 average exceeding 440 mm.

Snow coverage was 20% below the 2005-24 average.

To raise public awareness, the observatory launched the Mornos Reservoir Observatory.