Bicycle Tutor

I made a creek crossing that was deeper than I thought in the middle, followed by some fine almost sand- like gravel. Anyways its still grinding though not as bad as right after i rode through all of that. Is there a way to remove all that nastyness without flushing the grease from my hubs and without overhauling them?

I think you will have to bight the bullet and strip / overhaul the hubs.
It's the only way of guaranteeing getting every last grain out.