Arroyo Pucará is a stream in the Departamento Lácar of Neuquén province, originating in the Cordillera de los Andes near the Argentine-Chilean border and flowing to the narrows that separates Lago Lácar from Lago Nonthué. It drains into the upper watershed of the Chilean Río Valdivia. The stream runs entirely within Parque Nacional Lanín, which means any paddling activity is subject to the regulations of that protected area.

Near the mouth of the arroyo, there is a trail, a camping area with a small store, and a ranger station, making this the primary point of contact for visitors. Two families reside in the area. A botanical garden established in 1945, featuring a variety of tree species, is also located nearby. Sport fishing is permitted at the mouth of the stream, with mandatory catch-and-release rules in effect.

Paddlers should confirm current access permissions and any specific regulations with park authorities before planning a trip, given the stream's location within a national park and the presence of a ranger station near the confluence. No dedicated paddling infrastructure or established put-in and take-out points exist for this waterway.