Lago Puelo

Lago Puelo National Park was created in 1971 in the north-west of Chubut province, beside the Chilean border, and protects some 276 km² around the lake of the same name. It was previously part of Los Alerces National Park, from which it was separated as an independent unit.

Its singularity is biogeographical. The mountain pass in this area is unusually low, barely two hundred metres above sea level, and the lake drains towards the Pacific through the Puelo river, in the opposite direction to most Argentine Patagonian basins. That combination allows the moisture and the species of the Chilean Valdivian forest to cross the range and enter Argentine territory, so that species such as tique, lingue and avellano grow here and appear in no other Argentine national park.

The forest combines coihue, cordillera cypress, arrayán and radal, with a dense understorey of colihue cane. The fauna includes huemul, the deer endemic to the southern Andes and a national symbol of both Chile and Argentina, pudú, and Valdivian forest birds such as the hued-hued and the chucao. The park forms part of the Andino Norpatagónica Biosphere Reserve, brought into the world network in September 2007.