| 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 |
| 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) |
| Maximum 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.