To get over Harper's Pass you must be able to cross the Otira, Otehake and Taramakau Rivers on the first and second days of this tramp. There are no bridges crossing any of these rivers, so you need to utilise those river crossing skills to get through. The Otira is generally the worst of the three, if you can cross this river at Aickens Corner you should be able to cross the other two as well.
For more information on river crossing technique you should read the relevant sections of the MSC books: Bushcraft : outdoor skills for the New Zealand bush and River Safety: Be river safe.
Every serious tramper should have a copy of both of these books at home.
The Otira, Otehake and Taramakau are all killers: numerous people have been swept away trying to cross them in unfavourable conditions. They are always cold and can be deep and swift with even a hint of rain in the surrounding mountains.
This is the West Coast remember: it is always raining in the surrounding mountains.
|Taramakau Valley from near the Aickens car-park|
It is about 20-30 meters wide so it is a long way to back track if things started to look dicey during your crossing. I would still think about fording here but I would think long and hard before wading in.
|Otira River: First possible ford|
DO NOT CROSS HERE!
|Otira river view towards the flood track|
|View upstream: Otira River|
|Multi braided section of river I|
|Multi braided section of river II|
|Multi braided section of river III|
|Multi braided section of river IV|
Anyway that's what this beast looks like, whether it is the same in two weeks remains to be seen.
P.S: I gave a couple of TA walkers a ride from Arthur's Pass to Lagoon Saddle Track. One of them got swept away by the Otehake a couple of days earlier but managed to make it to shore. He freely admitted he just waded into the river and didn't take the time to study it well. Always study a river before entering the flow.