Embalse Paso de las Piedras is a large artificial reservoir in the southwest of Buenos Aires Province, Argentina, formed by the Dique Paso de las Piedras dam on the río Sauce Grande. The reservoir sits at approximately 38° 22' S, 61° 18' W, spanning the partidos of Tornquist and Coronel Pringles, roughly 30 kilometers from Sierra de la Ventana and about 100–120 kilometers northeast of Bahía Blanca. At full capacity it covers approximately 3,600 hectares (ranging from 2,752 to 4,000 hectares depending on water level), with a perimeter of 63 kilometers, a maximum depth of 32 meters, and a mean depth of around 8.5 meters. Total storage capacity is 328 million cubic meters. The reservoir collects runoff from the Sauce Grande basin, including drainage from the sierras of Curá Malal, Ventana, and De Las Tunas.

Paddling on this reservoir is explicitly prohibited. The Autoridad del Agua's Resolution 395/17 expressly forbids persons, animals, and watercraft from entering the water for recreational or commercial purposes, and prohibits all water sports of any kind. This restriction applies throughout the reservoir and its surrounding lands, with public access limited to designated sectors (Sectors 1 and 2 within Partido de Coronel Pringles, and Sectors 21 and 22 within Partido de Tornquist). Within those permitted sectors, activities such as lighting fires, camping, littering, cutting firewood, and hunting are also banned. The reservoir serves as the primary drinking water source for Bahía Blanca, Punta Alta, and surrounding communities, as well as supplying petrochemical and industrial facilities in the Bahía Blanca area, which explains the strict access controls.

The surrounding landscape includes wooded green spaces along the right bank, and the Hostería del Lago — positioned at the highest point of the reservoir's perimeter — once offered panoramic views over the water and surrounding fields, though the area has largely been abandoned. A 4,500-hectare provincial park (Parque Provincial Dique Paso de las Piedras) was established by provincial decree in 1982 to protect the reservoir and its natural surroundings, and the reservoir supports significant populations of aquatic birds. Access to the dam area is via a paved road of approximately 5.5 kilometers from Ruta Provincial 51.

Given the explicit prohibition on all water-based recreational activities, this reservoir is not a viable destination for paddlers.