Groundwater availability was evaluated by looking at the amount of groundwater that can be withdrawn from an aquifer without causing negative impacts. This amount is known as the aquifer’s sustainable yield. The negative impacts evaluated to determine sustainable yield included decreases in water levels that can affect neighboring wells and reductions in the amount of groundwater that seeps into streams and contributes to streamflow.

Results indicate that, for most of the aquifers in Georgia’s Coastal Plain, relatively large quantities of additional groundwater are available before sustainable yields are reached – with two exceptions. The first exception is the Upper Floridan aquifer in the Dougherty Plain. The second is the Upper Floridan aquifer in the Brunswick and Savannah areas, where movement of saltwater into the aquifer is a significant localized issue.

Smaller amounts of additional groundwater are also available from the Paleozoic rock aquifer in northwest Georgia and from the crystalline rock aquifer in the Piedmont and Blue Ridge, before sustainable yields are reached.

For all of the aquifers studied, the amount of water that can be sustainably withdrawn will depend, in part, on the location of new wells. Site-specific studies will be necessary to determine groundwater availability at a more detailed level.

Sustainable yields were determined by modeling differing amounts and locations for groundwater withdrawals. Determining the sustainable yield of all of the aquifers in Georgia would have been quite costly and time consuming. Studies were conducted on the most important aquifers, as indicated by the amount of water currently withdrawn and forecasts of significant increases in demand, among other characteristics.

This figure show the location of each aquifer studied and the forecasted groundwater demand for 2010 and 2050 (the crystalline rock aquifer was not evaluated for these years, so results are limited to 2009).

The range of sustainable yield for each aquifer is shown by the orange bar across each graph. Demand and sustainable yields are expressed in millions of gallons on an average day in a dry year (abbreviated mgd).