The Río Primero, also known as the Suquía — the name given to it by the indigenous Comechingones people — is a roughly 200-kilometer river that originates in the Sierras de Córdoba and flows eastward through the city of Córdoba before eventually emptying into the southern coast of the Mar Chiquita (Mar de Ansenuza) salt lake. The river's upper reaches and tributaries, including the San Roque and Cosquín rivers, feed into the San Roque Reservoir, from which the Primero continues its journey across the plains. The river carries an average flow of approximately 9.7 cubic meters per second, with a minimum of around 2 m³/s and a maximum of 24 m³/s, with peak flows occurring during the summer months. The mountain sections of the river and its tributaries run at elevations between 1,000 and 2,000 meters above sea level, producing clear, cold water that is well-suited to fly fishing. The broader Suquía basin encompasses several notable tributaries — the San Francisco brook, Cosquín river, Yuspe river, and San Antonio river — each offering its own fishing character. The river passes through a range of environments, from mountain slopes with cold, clear currents to lowland plains and wetland areas near its terminus.