Embalse Paso de las Piedras is a large artificial reservoir located in the southwestern corner of Buenos Aires Province, Argentina, formed by the damming of the Río Sauce Grande — a river whose name references the passage it carved through the Sierra de la Ventana mountains. Inaugurated in 1972 and completed in 1978, the dam and its reservoir serve as the primary drinking water source for Bahía Blanca, Punta Alta, and surrounding communities, while also providing flood control and irrigation for the semi-arid Pampas lowlands. The reservoir holds a total storage capacity of 328 million cubic meters and covers a substantial surface area, making it one of the most significant water bodies in the region. The surrounding landscape is characterized by open pampas farmland, riparian zones, and the rugged backdrop of the Sierras de la Ventana range. The reservoir and its shores fall within the Parque Provincial Paso de las Piedras, a protected area that manages both biodiversity conservation and public access. Despite its restricted-access status, designated fishing sectors make this a productive and popular destination for anglers targeting a diverse range of native and introduced species.