River Couzon

Couzon
Couzon valley from the D30 between Rive-de-Gier and Sainte-Croix-en-Jarez, above the dam (November 2008)
Country	France
Location	Rhône-Alpes
Physical characteristics
Main source	Mont Pilat
River mouth	Rive-de-Gier
Length	12.7 km (7.9 mi)
Basin features
Progression	Gier→ Rhône→ Mediterranean Sea
Basin size	34 km2 (13 sq mi)

Coordinates: 45°31′49″N 4°37′30″E / 45.530283°N 4.625109°E / 45.530283; 4.625109

The Couzon is a river in the Loire department of France, a tributary of the Gier, which in turn is a tributary of the Rhône. A dam on the river, built to serve as a reservoir for the Givors canal, now provides drinking water to the town of Rive-de-Gier.

The Couzon drains a basin of 34 square kilometres (13 sq mi) at a mean altitude of 550 metres (1,800 ft). It rises in the Pilat massif at an altitude of about 900 metres (3,000 ft). The river is 12.5 kilometres (7.8 mi) long. It runs through the communes of Pavezin, Sainte-Croix-en-Jarez, Châteauneuf and Rive-de-Gier. Tributaries are the Ruisseau Boissieux, Grand Valluy and Ruisseau de Chamerle.

In December 1788 King Louis XVI of France approved construction of a reservoir to supply water to the Givors canal in dry periods. François Zacharie, the canal's builder, had proposed a site for the reservoir high up near Saint-Étienne, but the chosen site was low down on the Couzon near to Rive-de-Gier. This short-sighted decision ruled out the plan to continue the canal up to Saint-Etienne via the Janon and then down to the Loire. The French Revolution (1789–1799) delayed the work, but construction of the Barrage de Couzon (Couzon Dam) was completed in 1811. The dam was operational by 1812. It was formally inaugurated on 23 September 1814 by the Comte d'Artois.