Unfortuantely, due to a potential liability issue, I have chosen not to display the chartlets sent along with Captain Michael's message below. However, there is still plenty of good info here concerning both St. Catherins Sound Inlet and the nearby Walburg Creek anchorage.

Dear Claiborne,
Your concerns notwithstanding, we ran outside from Savannah and went into St. Catherines inlet with the intention of spending the night anchored in Walburg Creek, which we did.  My chart is dated 2004, and I just couldn't believe that the charted depths could have shoaled to where we could not get in with 5' draft in 4 years.
The only place where the buoyage is different from what my chart shows is the location of the FlR "2" buoy at the entrance to the channel over the bar. The buoy has been moved to the (approximate) location shown by my waypoint on the StCathEnt.jpg file.  My arriving track shows how I adjusted to the edge of the shoal. I carried 12' over the bar at dead low tide.
In addition, the Middle Ground shoal off the north end of Walburg Creek has grown out to the east, and the shoal off the north end of St Catherines island has grown — both as shown in Walburg.jpg. We didn't hit bottom on our arriving track, but we did see some 7' depths, again at low-ish tide.
We also came in through Ponce de Leon Inlet and by reading the markers, the water, and watching other boats we had no problems.
Our best for the holidays, and thank you for your work with the sitge and guides.
Michael Porter
M/V Barbara