You can use cold water if it is brisk running creek. You are obviously looking for current to wash away the tannin acid. I would suggest using a sock or netting and leaving them for 24 hrs if you were to use this method. You are also correct on the the White Oak as being the preferred acorn to look for. I highly suggest you steer clear of acorns that come from trees in the Red Oak family. Be also advised that there are over 250 species of Oak.

A seasonal food in the worst of times if you know what your looking for and how to process them. Deer and turkeys also prefer the White Oak acorn over other acorns as well. Not to say that they will not enjoy certain trees more than another which is the case.