A) Have a conversation with a "trusted" friend that will assure you he made it last week when the water was this high too. Look at the crossing for your line through. Assess that you have only a 20% chance that you can ride on top of those moss-covered boulders and keep from sinking into 4-feet-deep water.
B) Make sure you do this early in the day. Who knows how long you'll be here!
C) Take the plunge. Stay on the pegs, feather the clutch, don't gas it too hard over those moss-covered boulders.
D) Know that only an insane person would attempt to do this, and do it anyway.
End of "Step One - The Plunge"