Water will get in your hubs and wheel bearings anytime you cross water like this, or even in rain and snow, etc...
Your best bet is to make it routine maint to re-pack the front wheel bearings, replace the grease seals, re-lube the brake caliper slide pins, and clean the hubs about once a year. More often the larger your tires.
Also anytime I get back from a wheeling trip, like to Moab for a few days, or deep water forging, sand whatever, I will re-do the bearings....
This will ensure a long life for the bearing, the correct load on the spindle nuts (bearings torque) and its a good way to keep up on the condition of your brake parts and hubs....
Anytime your Ex gets in water THAT deep it is imparative that you check/change all the fluids both diffs, tranny, oil, and t case. re-lube is not a bad idea either....
You shouldnt be going into water that deep unless your truck is prepared for it. Extended breathers, waterproofed computer(s), and a custom air intake etc can make life much easier....