1. Georgia Groundwater Management
Gail Cowie
Watershed Protection Branch
Groundwater Management Districts Association
May 31, 2018

2. outline Georgia’s groundwater resources and management framework
Lower Flint River Basin management initiatives
Coastal Georgia management initiatives
Regional water planning

4. Regulation of Water withdrawals
Permits for withdrawals above 100,000 gals/day
Municipal and Industrial
~500 active groundwater permits
~300 active surface water permits
Agricultural
>21,000 active permits
Ag metering

5. M&I Water Use Municipal and industrial withdrawals
Surface Water Withdrawals
Groundwater Withdrawals

6. Agricultural irrigation withdrawals

7. Lower flint basin management

8. Lower flint basin management
Area where Floridan aquifer and surface water have active hydraulic connection (approximate)
Describe the management challenges illustrated here: 1) economy reliant on irrigated agriculture, much of which comes from groundwater and 2) surface-groundwater interconnections – basin which has challenges during drought, recovers quickly but where drought impacts are evident and management is needed.

9. Flint river basin management
Improve information on water use and water resources
Sound Science Initiative (1999 – 2006)
Agricultural metering (2004 – Current)
Regional water plans (2010, 2017)
SSI: Geologic studies; Ag water use estimates (i.e., Ag water pumping studies); Ecological studies; Linked surface and groundwater models.
Alternate water sources means specifically looking at the Claiborne aquifer, described in subsequent slides

10. Flint river basin management
Improve information on water use and water resources
Sound Science Initiative (1999 – 2006)
Agricultural metering (2004 – Current)
Regional water plans (2010, 2017)
Policy responses to improved information
Permitting moratorium (1999 – 2006)
Basin-specific permitting plan (2006)
Drought Protection Act and amendments (2000, 2006, 2014)
Agricultural permitting suspension (2012 – Current)
Assessment of alternate water sources (2014 – Current)
SSI: Geologic studies; Ag water use estimates (i.e., Ag water pumping studies); Ecological studies; Linked surface and groundwater models.
Alternate water sources means specifically looking at the Claiborne aquifer, described in subsequent slides

11. Current agricultural permitting suspension
Skip this slide and just describe verbally?

12. Evaluation of alternate water sources
Evaluation of data from selected existing wells and from eight new test wells:
6 GEFA test wells (shown in green)
2 USGS test wells (shown in orange)
We started by looking at all the existing Claiborne wells and there are a number – many more than shown on this slides. Most are in the northern and western portion of the aquifer.
We evaluated information on those wells and selected those that had complete lithologic logs, so it was clear where they were in the formation, as well as pump tests that reported specific capacity estimates. We also contracted with USGS to log and collect water quality data from 6 additional private wells when they were drilled.
This subset of wells is shown in red and blue on the slide – again, this is a small subset of the existing Claiborne wells.
Then, in areas where we did not have wells with sufficient data available, we contracted for 8 new test wells. Shown on this slide. The six GEFA wells were used to collect basic water quality data and for a 24-hour specific capacity test.
At the two USGS wells, a full aquifer test was conducted: a pumping well in the Claiborne and a monitoring well in each of the Claiborne and the Floridan aquifers. Allowed for direct estimation of transmissivity as well as an assessment of leakage between the Floridan and the Claiborne during a 72-hour pump test.
So, have a variety of information. One type is shown in the following slide from a draft report.

13. Evaluation of alternate water sources
Where the Claiborne aquifer is thinner, specific capacities can be relatively high.
Where specific capacity is lower, the aquifer is thicker. Productive wells can be completed because a larger drawdown is possible.
In all areas, availability may be limited by other users.
These results show the specific capacity that might be expected for a standardized well in different areas.
Results are shown for a standard or normalized specific capacity measurement based on the following assumptions: 18” borehole, screen length into the Claiborne of 300’ or less, and a specific capacity test duration of 24 hours. The unit of measurement is gallons per minute per foot of drawdown.
Results indicate that there are areas where more water may be available from the aquifer.
In the northeastern area, specific capacities are higher. But, the aquifer there is shallower so there is not as much room for drawdown and that can limit the overall productivity of a well. And, remember that there are existing wells that will limit the ability to place new wells and many are in this area.
Moving to the south, the specific capacity is lower, but the aquifer is deeper and there is room for greater drawdown. So, the productivity of a well can be higher.
The USGS tests also looked for evidence of leakage between the Floridan and Claiborne aquifers at the Mitchell and Early County sites and they did not see any evidence of leakage between those two aquifers.
Finally, beyond these results, the significant conclusions from this work relates to the model we’ve used for Claiborne modeling. Results also tell us that some of the parameters used in the model to estimate Claiborne sustainable yield will have to be adjusted, transmissivity in particular. The sustainable yield will then have to be re-calculated as an indicator of the aquifer’s overall capacity to support additional demand.
In short, the field studies have demonstrated that there are areas of the aquifer where more water is available and that we need to update the tool we use to estimate total capacity. This is another valuable outcome of this field work and model revisions are nearing completion.

14. Coastal groundwater management
Long-term GW challenge on the coast is saltwater intrusion – affecting two areas with two slightly different mechanisms

15. Coastal groundwater management
Reference Brunswick issue but focus on the Savannah-Hilton Head area.

16. Upper floridan potentiometric surface
Before pumping of the Upper Floridan aquifer started in the 1880s the direction of groundwater movement was toward Port Royal Sound and the Atlantic Ocean and groundwater from the aquifer discharged to the sound and ocean. The depiction on the right shows the USGS’s interpretation of flow conditions in the aquifer prior to development. The Floridan aquifer in the Savannah area was artesian. Extensive pumping of the Upper Flordidan aquifer started in the 1880s in Savannah and in the 1960s in Beaufort County South Carolina. This pumping created a cone of depression that lowered the hydraulic heads to below sea level so that the aquifer is no longer artesian. The direction of groundwater movement was also changed. When the aquifer was artesian groundwater movement was toward the sound and ocean to the northeast across Hilton Head Island. Now it is toward the Savannah area cone of depression located southwest of Hilton Head Island, a 180 degree change in the direction of groundwater movement.
Before pumping of the aquifer started, groundwater discharged to Port Royal Sound sound and the Atlantic Ocean by leakage through the confining unit or by discharge from underwater springs. Pumping of the Upper Floridan aquifer [reversed this], causing salt water to move from the sound and ocean into the aquifer.
USGS SIR

17. Saltwater plume migration

18. Coastal groundwater management
Improve information on water use and water resources
Coastal Sound Science Initiative ( )
Monitoring and modeling of the Floridan aquifer system (2006 – Current)
Regional water plans (2010, 2017)
CSSI: Aquifer tests and seismic studies; Ag water use estimates; groundwater monitoring; and groundwater modelling.
Under 2006 permitting plan, permit holders have made specific reductions in their withdrawals, in part through meeting special water conservation conditions
Specific provisions of 2006 plan: see word doc notes
2013: Studies by EPD and USGS showed more substantial interconnections between the Upper and Lower FL than previously recognized. As a result, EPD issued a moratorium on new withdrawals (M&I) from either AQ in 2013.
2015: Additional reductions in M&I withdrawals.

19. Coastal groundwater management
Improve information on water use and water resources
Coastal Sound Science Initiate ( )
Monitoring and modeling of the Floridan aquifer system (2006 – Current)
Regional water plans (2010, 2017)
Policy responses to improved information
Interim Strategy to Manage Saltwater Intrusion (1997)
Basin-specific permitting plan (2006)
Moratorium on new withdrawals (2013)
Additional reductions in groundwater withdrawals (2015)
Evaluation and use of alternate water sources (Ongoing)
CSSI: Aquifer tests and seismic studies; Ag water use estimates; groundwater monitoring; and groundwater modelling.
Under 2006 permitting plan, permit holders have made specific reductions in their withdrawals, in part through meeting special water conservation conditions
Specific provisions of 2006 plan: see word doc notes
2013: Studies by EPD and USGS showed more substantial interconnections between the Upper and Lower FL than previously recognized. As a result, EPD issued a moratorium on new withdrawals (M&I) from either AQ in 2013.
2015: Additional reductions in M&I withdrawals.

20. Groundwater permit limit reductions
Reductions implemented where available alternate water supplies exist.
Groundwater withdrawal permit limits (annual average) were reduced on December 31,
In RED zone, reductions are staged for 2020 and 2025
In YELLOW Zone, reductions are staged for 2025.
Red zone reductions from 60 mgd to 50 mgd by 2020 to 45 mgd by 2025 (2012 baseline).
Yellow zone is less populated; goal is to reduce 1.0 mgd by 2020 (2012 baseline).
Scenario modeling by USGS shows that even with pumping eliminated for an extended period of time (100 model years) the salt water plume pretty much stays in place.
Note stakeholder and public processes undertaken throughout each of these in effort to involve water users and those affected by policy responses – particularly in the recent reductions in withdrawals
Alternate water sources: Floridan in areas outside red/yellow zones, surface water, other aquifers (Miocene and Cretaceous)
Red zone -- Off the top permit limit reductions were implemented for:
GA Power Co - closing Plant Kraft – some water was transferred
Hunter Army Airfield – EPD revoking unused LF permit
Tybee Island – reductions contingent upon productive Cretaceous well
City of Savannah – Genesis Point in Yellow Zone transferring to Bryan County
Permits with no alternative water supply were unaffected:
Skidaway Institute of Oceanography
Skidaway Island Utilities
Pro-rata reductions to reach the targets were applied to all others after incorporating the above reductions
Yellow zone -- a Pro-rata reduction was applied to all Yellow Zone permit holders.

21. Regional water planning

22. MILESTONES IN GEORGIA’S WATER PLANNING
Georgia’s State Water Plan adopted
Regional Water Plans adopted
Metro Water District plans revised
Comprehensive State-wide Water Planning Act passed
Revised plans adopted by Regional Water Councils and Metro District
Metro Water District adopted three regional water plans
Metropolitan North Georgia Water Planning Act passed, creating Metro Water District
2001
2003
2004
2008
2009
2011
2017

23. Basic elements of regional water plans
Vision and goals
Water and wastewater demand forecasts
Resource assessments
Management practices to meet demands and goals
> Plans guide permits and state funding for infrastructure
Resource assessments =
Modeling of surface water, groundwater, and assimilative capacity
Estimated capacity of resources to meet demand within thresholds indicating potential for local or regional impacts
For groundwater, estimated sustainable yields for prioritized aquifers

24. Groundwater sustainable yield estimates

25. Groundwater sustainable yield estimates
Forecasted demand
(2016 update):
2015 – 619 MGD
2050 – 731 MGD

26. Groundwater assessments: 2017 updates
Regionally-focused studies
Capacity of groundwater to replace surface water use
Monitoring recommendations
Assess additional aquifer unit
Assess aquifer characteristics and capacity for additional use 2 1 3 1
Claiborne:
- Field measurements of aquifer characteristics across the region and modeling of capacity to support increased use – all to better characterize the Claiborne’s capacity as an alternate water source 4

27. Management practices & Recommendations
Water conservation
Master planning
Enhanced surface storage
Additional groundwater use
Wastewater returns
Stormwater management
Nonpoint source controls
Recommendations to state

28. epd.georgia.gov/ watershed-protection-branch
questions
epd.georgia.gov/ watershed-protection-branch