Initial construction 1685–1690 (≈ 1688)
Directed by Nicolas Le Jongleur, king's fontainerier.
1731
Capacity expansion
Capacity expansion 1731 (≈ 1731)
First major extension work.
1778–1798
New developments
New developments 1778–1798 (≈ 1788)
Upgrading of existing water supply.
1855
Creation of a new pond
Creation of a new pond 1855 (≈ 1855)
Addition among the ponds of Retz.
1866
Replacement of the tank
Replacement of the tank 1866 (≈ 1866)
Water castle on the Market Square.
1910
Change of use
Change of use 1910 (≈ 1910)
Exclusive golf food.
1988
Registration historical monument
Registration historical monument 1988 (≈ 1988)
Protection of remaining remains.
Aujourd'hui
Aujourd'hui
Aujourd'hui Aujourd'hui (≈ 2025)
Position de référence.
Heritage classified
Aqueduct, as a whole, with its external works: old gaze, new gaze and reservoir of Montaigu (cad. C 492, 401; B 481): entry by order of 17 May 1988
Key figures
Nicolas Le Jongleur - King's Fontanier and Master Worker
Directed the construction (1685–90).
Origin and history
The Retz Waterway is a 6 km underground hydraulic structure between Chambourcy and Saint-Germain-en-Laye in the Yvelines. Built mainly between 1685 and 1688 under the direction of Nicolas Le Jongleur, the king's fontainerier, it was designed to bring water from the valleys of the Ru of Buzot and the plateaus of the Aluets and Marly to the castle of Saint-Germain-en-Laye. Its layout includes a milling gallery of 0.80 to 2 m high, fed by springs and ponds such as those of Retz, as well as by eyes allowing its maintenance.
In the 18th century, work between 1731 and 1798 increased its capacity, while in the 19th century major changes took place: construction of a new pond in 1855, replacement of the reservoir of the Place du Marché by a castle d'eau in 1866, and creation of the Montaigu reservoir. Starting in 1910, the aqueduct mainly fed the golf course of Saint-Germain-en-Laye and some local fountains. In 1951, part of his conduct was reused for a subdivision, and in 1988 his remains were listed as historical monuments.
The lake operated thanks to a complex system combining underground galleries, siphons and reservoirs (retz ponds, Montaigu and Market reservoirs). Its decline progressed with the arrival of pumps drawing from the Seine in the 19th century, then from artesian wells between 1930 and 1942. Today, it is used only for the irrigation of the golf of Saint-Germain-en-Laye, the surplus flowing into the Buzot Ru. Hennemont and Dauphine, as well as the Montaigu Reservoir, still bear witness to his historical engineering.
