I first ran the Río Blanco back in 1991 with John Foss. We had come across the river while driving south to Futaleufú. I had not seen the river again until December of 2008 when I returned to area to explore the nearby Río Negro.
View of Rio Blanco upstream from takeout bridge
The Blanco is a glacier fed river (not creek) flowing out of Parque Pumalin. The riverbed is littered with granite boulders which makes for a nice class 3-4 run through some pristine surroundings.
To reach the takeout leave town Plaza in Hornopirén and drive south on Carretera Austral for 6.5 KM to Puente Rio Blanco. To reach put-in back track 100 meters to a fenced road. If the gate is open you might be able to drive up but expect to shoulder your boat for the 4 km hike to end of road.
At this point you reach a house and need to find your way to the river. It is tricky but you will figure it out. Expect to lower your boats (perhaps with ropes) through a bamboo jungle.
The put-in is unforgettable. The whole river basically erupts from a fissure in the rock wall. Expect flows of 1000 to 2000 CFS. We had no portages but be wary of logs.
Note: the takeout of the outstanding Rio Negro creek run is only 3.7 KM away. See description on this website. It is good to combine a trip on the Blanco with a descent of nearby Río Negro and the Cochamó as well.