Timeline

Heritage classified

Key figures

Origin and history

The Retz Waterworks is a 6 km underground hydraulic structure built mainly between 1685 and 1688 under the direction of Nicolas Le Jongleur, king's fontainerier. It connected the Ru Valley of Buzot to the Château de Saint-Germain-en-Laye, via a high milling gallery of 0.80 to 2 meters. Its route crosses the communes of Chambourcy and Saint-Germain-en-Laye, with four eyes allowing access to the pipeline. The water was captured on the plateaus of the Aluets (by piers) and Marly (via an annex gallery and a siphon), before being stored in reservoirs such as Retz ponds or the market square.

The construction met the growing water needs of Saint-Germain-en-Laye, which was not well met by the old sandstone aqueduct (the Grand Cour). Major extensions took place in 1731, then between 1778 and 1798, with a redesign of the system by architects Soufflot, Hazon and Guillaumot, modified in 1783 by Cellier. An iconic look, that of Hennemont, was rebuilt between 1784 and 1787 after a first version of 1733 by local religious.

In the 19th century, the aqueduct was modernized: a new pond was dug in 1855, the market square reservoir replaced by a water castle in 1866, and the Montaigu reservoir built. The arrival of pumps from the Seine reduced its use, before it was used exclusively for golf in Saint-Germain-en-Laye from 1910. In 1951, part of his conduct was reused for a subdivision. Ranked a historic monument in 1988, it remains as evidence of the hydraulic techniques of Ancien Régime.

Today, the aqueduct still feeds the golf course, with its overflow flowing to the Buzot Ru via the Montaigu reservoir. The eyes of Dauphine and Hennemont, as well as the remains of the gallery, are protected. Its history illustrates the evolution of water needs, from 17th century royal techniques to 19th century industrial adaptations, before its gradual decline in the 20th century.

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