Marathon Dam

Marathon Dam
The dam and reservoir
Location of Marathon Dam in Greece
Country	Greece
Location	Marathon
Coordinates	38°10′01″N 23°54′19″E / 38.16694°N 23.90528°E / 38.16694; 23.90528Coordinates: 38°10′01″N 23°54′19″E / 38.16694°N 23.90528°E / 38.16694; 23.90528
Status	In use
Construction began	1926
Opening date	1929
Owner(s)	EYDAP
Dam and spillways
Type of dam	Gravity
Impounds	Charadros River
Height	54 m (177 ft)
Length	285 m (935 ft)
Width (crest)	4.5 m (15 ft)
Width (base)	28 m (92 ft)
Spillway type	Service, uncontrolled chute
Spillway capacity	520 m3/s (18,364 cu ft/s)
Reservoir
Creates	Lake Marathon
Total capacity	41,000,000 m3 (33,239 acre·ft)
Active capacity	34,000,000 m3 (27,564 acre·ft)
Inactive capacity	7,000,000 m3 (5,675 acre·ft)
Catchment area	118 km2 (46 sq mi)
Surface area	2.45 km2 (1 sq mi)
Max. water depth	54 m (177 ft)

The Marathon Dam is a gravity dam on the Charadros River, near its junction with the Varnavas Stream, 8 km (5 mi) west of Marathon and 45 km (28 mi) northeast of Athens in Greece. The dam created Lake Marathon for the primary purpose of municipal water supply. Constructed between 1926 and 1929, it was the sole supplier of water to Athens until 1959. The dam is often cited for its role in the modernization of Greece and the first recorded case of seismic activity associated with reservoir inundation. It was also designed to be symbolic of Ancient Greece, particularly Athenians and the Battle of Marathon.

The Marathon Dam was originally proposed, designed, funded and tendered in 1918, but was declared illegal by Prime Minister Dimitrios Gounaris, who succeeded Eleftherios Venizelos in late 1920, because there had been no public bidding for the project. With a strong influx of Greek refugees from Asia Minor following the defeat at the Greco-Turkish War of 1919–1922 (the "Asia Minor Disaster") and the 1923 Treaty of Lausanne, which led to the population exchange between Greece and Turkey, Greek officials were searching for a means to supply Athens with more water. An estimated 1.3 million refugees were returning and the population of Athens would end up doubling between 1920 and 1928. At the time, Greece underwent a period of political turmoil that saw the fall of the monarchy and the establishment of a Second Hellenic Republic, as well as several military coups and counter-coups. Near the end of this period, all major water supply projects for Athens were reevaluated and a five-volume report was published. The report described the Marathon Dam as "the optimal solution" and the "last recourse" for Athens.