The Alzou () is a short river in the Lot département, southern France, a right tributary of the Ouysse. It is long. It flows through the towns of Gramat and Rocamadour, and joins the Ouysse, itself a left tributary of the Dordogne, downstream of Rocamadour. The valleys of both the Alzou and the Ouysse are deep limestone canyons.
thumb|240px|Ruins of the moulin du Saut
The river once powered the watermill moulin du Saut, whose ruins can be visited on foot.
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File:Moulin du Saut 1 Stevage.jpg|Inside the moulin du Saut
File:Moulin du Saut 4 Stevage.jpg|An outbuilding of the moulin du Saut
File:Canyon de l'Alzou, entre Gramat et Rocamadour.jpg|View over the Alzou valley
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