For modern views of the area, see the current maps at the NOAA site.
http://www.marinewaypoints.com/learn/charts/AtlanticCoast.shtml. I would suggest map no. 11512, “Savannah River and Wassaw Sound” as your basis. Navigate around with the arrows, and expand to check specific areas and features. Notice that the name St. Augustine Creek is now attributed to the connector (running southeast below the Savannah River) toward Wilmington Narrows (Freeborn’s Cut), while the name “Wilmington River” is now extended upstream to encompass the original St. Augustine Creek as it branches off Savannah River below Mackeys Point.
Other maps in this site may be accessed for details up Savannah River to Brier Creek (11514) and on to Augusta (11515), north from Tybee Roads to Port Royal Sound (111513), and south to Ossabaw Sound and beyond (11511).
Another NOAA site of value is http://www.historicalcharts.noaa.gov/about.html. Click on SEARCH IMAGES, then click “Select Point on Map,” or type Savannah, GA” in search window under “Enter a Geographic Place Name.”