See this trip report for details.
Mules can't make it and walking is both dangerous and very hard. Under normal conditions the walk up to the refugio at Laguna Blanca is taxing, but beautiful and straight forward.
To your north you have the 5300m high Trabante II, with a small glacier on it's south face. There are many small streams here. Looking towards Mercedario, which isn't visible at this point, you can see a long ridge which terminates in Pilar Grande in the west. Walk up in the valley to the left of Pilar Grande.
There are lots of places where climbers have camp also further up this valley. When you arrive at steep scree slope, hold to your left and look for trails which switch-back up the slope on to a ridge. Follow the ridge until it's getting flat enough to walk up.
You're now at a little saddle overlooking Cerro Negro and to your right you have the northern glacier.
Start walking straight to the west on path of least resistance. It's a long walk, but it's very straight forward. Continue walking until you're almost at the end of the valley. You'll see the little north face glacier and you can either choose to climb on the ice or if the snow conditions are good; go straight up the summit. It's on average about 35 degrees, but at points it may be a bit more.
Depending on your line, you either end up just below some rocks, which is the summit or on the west ridge. If the latter, you have and easy walk to the little summit, if not scramble the rocks to the summit.
The views are outstanding!
To the south you have the whole of Cordillera de la Ramada and the slopes leading to Mercedario's south face. In the distance you can clearly see Aconcagua on a cloudless day. In the north you can enjoy the views of the Ansilta range.
Essential GearWarm clothing, plenty of water, crampons and if icy, you may want to bring an ice axe.
Where to start from?
Paso Ancho, the alternative route to north side of MercedarioThe flash flood of Las Molles (see above) made the normal walk in route almost impossible to travel.
There's an alternative.
You can enter via Valle Colorado, which is the normal route in to Mercedario's south face and Ramada. See the Ramada page for details about the walk in.
When you have made it to Campo de los Polacos, in the end of Valle Colorado you cross the wide river bed and aim for Cerro Negros right side. There's a trail leading up the steep slopes and in the beginning there's no way to go wrong. When you have reached a flattish part of the path, look for the trail. It may be hard to find.
The valley gets steeper and on your right you'll see ridges of different colors. The last one, the horizon ridge is black, the next is red and the one closest to where you stand is yellow in color.
You can either follow the guanacos tracks straight up the yellow ridge or walk in between the red and the yellow ridge.
The latter alternative was the recommended one, but some Polish climbers I met said they had be very frightened by the fresh signs of rock avalanches and I'm happy I went on the guanacos trails instead.
These trails are very steep and at times you're extremely exposed, considering you probably have a heavy back pack on your back. 200 m from Paso Ancho there's a nasty slide zone. Pass this one quickly! At 4750m you're at the pass and at the Ancho Plateau. It's an open valley where you can camp if tired, or want to climb Negro or Wanda. There are plenty of water up here, but very little in between Campo de los Polacos and this place.
Continue in between Negro and Wanda until you reach the end of the valley. Don't walk down to the lowest point in that valley, but follow the ridge on the left hand side until it starts go go up again. At a high point you'll see patches of grass far below and also an old mining road. There are guanacos tracks to follow down to the road.
From there you either walk down the road to the turn-off to the normal walk in to Mercedario or traverse the east ridge. If going all the way down to the normal route, you'll loose about 300 vertical meters.
The route over Paso Ancho is not to be taken lightly. It's a hard traverse if you carry all your gear, but it may be the only reasonable alternative to reach the north side of Mercedario. Whatever anyone tells you; this alternative is much easier than trying out the walk past Las Molles under present conditions.