The Río de la Reconquista is a small river in Buenos Aires Province, approximately 82 km in length, flowing through 18 municipalities before emptying into the Río Luján near Tigre. It originates at Dique Roggero, where the arroyos La Choza and Durazno converge to form Lago San Francisco in the partido of General Rodríguez. Its drainage basin covers 1,670 square kilometers and is home to roughly 4 million people.

For paddlers, the river presents serious practical challenges. Under normal conditions, water levels are extremely low — as shallow as 30 cm in stretches between the second inflatable dam at Cascallares and Avenida Roca at the Camino del Buen Aire crossing — making paddle strokes hit bottom. In some sections near the Ruta 7 bridge at Paso del Rey, sediment accumulation has created mid-river islands with trees reaching 5 meters in height, a direct consequence of chronically low flow. The river becomes navigable only after heavy rainfall combined with the opening of the Dique Roggero floodgates to regulate lake levels; however, this same combination produces strong, dangerous currents that create significant hazards for paddlers.

The river is widely recognized as one of the most contaminated watercourses in Argentina, alongside the Riachuelo. Water quality is a serious concern throughout most of its length. Downstream sections, particularly from Moreno onward, are heavily affected by waste and litter. The upper reaches near the Dique Roggero are considered the most natural and least degraded portion of the river.

A roughly 39 km stretch from Paso del Rey to Tigre has been discussed as a potential paddling route, but paddlers familiar with the river caution that this is only feasible under post-rainfall, high-flow conditions — which simultaneously introduce hazardous currents. A kayak rescue involving six minors was recorded at Rincón de Milberg, underscoring the risks that can arise even on shorter outings. Given the combination of contamination, unpredictable navigability, and flood-driven current hazards, the Río de la Reconquista is not considered a practical or safe paddling destination under most conditions.