The Marathon Dam and Lake – Το Φραγμα και η Λιμνη του Μαραθωνος

Marathon Lake and Dam
Marathon Lake and Dam

I live in a small village called Kaletzi (or Vothon) 2 km east of the artificial lake of Marathon, in the Attica region of Greece.

This post is about the lake and the dam that created it in the early 1930s.

The Marathon area is more or less 40 km away from Athens, the capital of Greece. Today approximately 5 million people live in the Athens greater metropolitan area. There is plenty of water to accomodate the needs of this population.

This was not the case at the end of the 19th century.

Water distribution in Athens, early 20th century
Water distribution in Athens, early 20th century

Athens did not have regular water supply. Water was distributed to the population over a network of fountains and taps that were most of the time dry (1).

After the 1922 Minor Asia defeat of Greece and the exchange of populations with Turkey, it was estimated that the population of Athens would double. Something had to be done about the water supply.

The situation changed when the Marathon articifial lake was created, after the construction of the Marathon dam.

The Marathon dam was constructed by an American firm, Ulen & Company.

At this point I have to introduce Henry C. Ulen, the key person behind the company.

Henry Ulen's home in Indiana, USA
Henry Ulen’s home in Indiana, USA

Henry Ulen was born in Lebanon, Indiana, USA, in 1861.

In 19th October 1912, The New York Times wrote in an article “Twenty five years ago (1887), Henry Ulen was a tramp.” (2)

In his own words, Ulen is quoted as saying “I was a pretty wild lad, and when I was sixteen, I run away from my home in Lebanon, Indiana.” (2)

But Henry Ulen was not destined to remain a tramp. He became a businessman, and a banker.

Marathon dam - construction
Marathon dam – construction

Ulen & Co. was incorporated under the laws of the State of Delaware on the 15 February 1922. (3) At the time Ulen had signed contracts to build water and sanitation facilities and railroad lines in South America. The newly incorporated company would finance and carry out the construction of these projects. In 1929 principal stockholders in the firm were American International Corporation, organized in 1915; Field, Globe and Company (a banking concern run by Marshall Field (son of the Marshall Field retail magnate)); Stone and Webster, one of the largest engineering contracting companies in the world; and Ulen Contracting Corp.(4)

Ulen & Co,. did not do business only in South America. In 1924, Ulen began work on water and sewer projects in ten Polish cities. (4)

Marathon dam - construction
Marathon dam – construction

On December 1924, after a restricted public tender, the Greek Government, and the Bank of Athens sign a contract with Ulen & Co. to build the Marathon dam and the pipeline to transfer the water to a water treatment facility in the Galatsi neighbourhood of Athens.. The project would be financed by issuing bonds worth a total of 10 million US dollars.  A new entity was incorporated, the “Public Water Company of Athens Piraeus and Suburbs, with two shareholders. Bank of Athens (today the National Bank of Greece) had 50% of the shares and Ulen & Co. had the other 50%. The new entity would have the right to operate the water facilities it would build for a minimum of 22 years. Ulen got out by selling its shares to the National Bank of Greece in 1974.  In article 22 of the relevant contract, it was stated that water would be priced in a way that would cover the new entity’s costs and profits.

Marathon dam - Plaque
Marathon dam – Plaque

Ulen & Co. also signed another contract with the Bank of Piraeus in order to incorporate the Greek Water Company (Ελληνική Εταιρεία Υδάτων ΑΕ). The company became the owner of the water distribution network of Athens, and the Municipality of Athens had from now on to pay the newly established company for the supply of water.


In 1928 Ulen & Co. landed a huge project in Persia to construct 800 miles of railroad from the capital of Teheran to the Persian Gulf. (4)

In 1931 an Indiana magazine reported that Ulen and Co. was the “largest engineering and contracting corporation in the world” with millions of dollars in contracts each year. (4)

Marathon Lake
Marathon Lake

The foundation stone for the Marathon dam was laid in October 1927 by Prime Minister Alexandros Zaimis; Venizelos was also present at the ceremony. (5)

The dam was completed in 1929 and solved the water supply problem of Athens.

Marathon Dam
Marathon Dam

The dam is a 54 m (177 ft) tall, 285 m (935 ft) long gravity dam with a crest width of 4.5 m (15 ft) and base width of 28 m (92 ft). (5)

The dam’s face and visible structure were also covered in the same Pentelikon marble that was used to construct the Parthenon. (5)

Exit to Athens
Exit to Athens

The dam would serve as the primary water supply for Athens until 1959, when water was pumped from Yliki lake.(5)


1. Βρύσες, κρήνες και νερό νεράκι… (Fountains, taps, but no water)

2. Banker saw world first as a tramp. The New York Times, 19 October 1912.

3. Delaware concern to carry on South American concern. The New York Times, 16 February 1922.

4. Henry Ulen. Small town boy. Worldwide impact.

5. Marathon Dam, wikipedia.