On the Zongo Pass (start of the Normal Route on Huayna Potosi) was investigated in winter 1998 by Branko Ivanek for its water ice potential. On the 23rd July, Ivanek and Bolivian guide, Marco Soria, climbed an 80m icefall on the flanks of Pico Milluni (5,400m and home to the excellent French route up the Central Couloir: 440m: D). The route, which was christened Amistad, began at an altitude of 4,940m and involved two pitches on ice that was five to 10cm thick and up to 90°.
On the 27th August, Ivanek returned to solo two icefalls on the right-hand side of the lower part of the Huayna Potosi Glacier. Zongo Light was 80m high with a maximum angle of 80° and graded (USA/French) III/3+, while Cha'qui was 140m in height with a maximum angle of 70° and graded II/2+. However, prior to this exploration British climber, Neil Brodie and Patrick Berthet from France had climbed two icefalls on the 13th June. Located to the right of Amistad, Branko Blues was graded III/5, while Bolivian Journeys received a grade of III/4+.
public bus: 1 a day, 5 am from Plaza Ballivan/El Alto but very packed and area not safe in darkness
shop around , you should get a taxi from downtown to Paso de Zongo for about 15-18 US $ (haggle hard) -
you can agree with the driver that he picks you up again,but don´t count on it - almost no public transport going back from Paso de Zongo after midday (no pt on sunday) - you can ask at the COBEE (electrical company) at Paso de Zongo if they could contact their collegues further down in the valley, sometimes they drive you to El Alto in one of their pickups
Costs from Bolivian Mountains for roundtrip transport to the pass was $100 USD.
Somebody is making easy money in "Bolivian Mountains". Round trip on a public rural bus from El Alto is about $5 USD:)
There is second refuge at ~17k. Details at http://www.summitpost.org/phpBB2/viewtopic.php?t=35739
it can be possible to climb Huayna Potosi all year round depending on how lucky one gets with the weather. I climbed it with a tour in January 2014 without big problems. The nice thing is that there's not as much traffic on the mountain and it doesn't get as cold. Weather on the other side is less stable and higher probability of summiting in a cloud and not seeing anything...
You can watch a 5 minute video here: https://www.youtube.com/watch?v=3-tF76IZE4s