Introduction

Reliable and impartial scientific information about the occurrence, quantity, quality, distribution, and movement of water is essential to resource managers, planners, and others throughout the Nation. The U.S. Geological Survey (USGS), in cooperation with numerous local, State, and Federal agencies, collects hydrologic data and conducts studies to monitor hydrologic conditions and better define the water resources of Georgia and other States and territories.

Groundwater-level and groundwater-quality data are essential for water-resources assessment and management. Water-level measurements from observation wells are the principal source of information about the hydrologic stresses on aquifers and how these stresses affect groundwater recharge, storage, and discharge. Long-term, systematic measurement of water levels provides essential data needed to evaluate changes over time, develop groundwater models, forecast trends, and design, implement, and monitor the effectiveness of groundwater management and protection programs (Taylor and Alley, 2001). Groundwater-quality data are necessary to protect groundwater resources, because deterioration of groundwater quality may be virtually irreversible, and treatment of contaminated groundwater can be expensive (Alley, 1993).

Map of Major Georgia Aquifiers

Purpose and Scope

This website presents an overview of groundwater levels throughout Georgia. It is a continuation of a series of reports begun in 1978. Water-level data are summarized in graphs and maps. Groundwater levels in major aquifers are presented on hydrographs for selected wells. Data from additional information about the wells included in this report can be obtained from the USGS National Water Information System (NWIS) database at http://waterdata.usgs.gov/ga/nwis/gw/.

Cooperating Organizations and Agencies

Groundwater monitoring in Georgia is conducted in cooperation with numerous local organizations, private companies, and State and Federal agencies. Cooperating organizations and agencies include the following:

  • City of Albany Utility Operations
  • Augusta Utilities Department, City of Augusta
  • Georgia Department of Natural Resources, Environmental Protection Division
  • Glynn County Joint Water and Sewer Commission
  • Miller Coors LLC
  • The U.S.G.S. Water Mission Area National Groundwater Monitoring Network

Organizations have access to USGS Cooperative Matching Funds (CMF) which support joint projects with state, regional, tribal, and local partners to provide reliable, impartial, and timely information needed to understand and manage the Nation's water resources. A more complete description of the CMF is provided on the USGS Cooperative Matching Funds website: https://www.usgs.gov/mission-areas/water-resources/science/usgs-cooperative-matching-funds?qt-science_center_objects=0#qt-science_center_objects (USGS, accessed June 4, 2021).

Linear Trend Lines and Regression Statistics

Water-level trend lines are generated by Simple Linear Regression. The "Simple Regression" button calculates the trend line for the current set of data displayed in the graph.
Dates with null values are not used in the trend line calculations.

η represents the sample size

y-intercept a = [ (∑y)(∑x2) - (∑x)(∑xy) ] / [ η(∑x2) - (∑x)2 ]

slope b = [ η(∑xy) - (∑x)(∑y) ] / [ η(∑x2) - (∑x)2 ]

Example of Data/Trend Graph

Example of Trend Anaylsis Graph with trend line and control buttons.

Arrow icons for the maps represent the upward or downward trend, and are calculated using the last 10 years of data. Simple Linear Regression is used to calculate the trend. If the well does not have 10 years of data, or if the trend is less than .01 ft/year, a circle icon is displayed, instead of an arrow. Split color icons represent wells with trend analysis graphs at the bottom of each aquifer page.

Example of Map with Arrow Icons

Example of map with arrow and circle icons

Methods of Analysis, Sources of Data, and Data Accuracy

Hydrologic Conditions for Select wells

The hydrologic conditions for select wells are summarized annually using the groundwater-level monthly statistics tables from NWISweb (https://waterdata.usgs.gov/nwis/gw). These tables present the monthly mean depth to water level in feet below land surface for each month (columns) of every year (rows) during the period of record for a particular well. The last row in the table is the mean of the monthly means (the mean of all January means in the period of record, the mean of all February means in the period of record, etc.). The range of the mean of monthly water levels for the current year is compared to the range of the mean of monthly means (last row in the table) to determine if water levels during the year were generally above or below mean water levels for the period of record. For example, USGS has been continuously recording water levels in well 16MM03, a crystalline rock aquifer well in the Piedmont/Blue Ridge, since 1988 (Period Of Record "POR" from 1988 to present). The maximum mean of monthly mean water levels for well 16MM03 for this POR is 3.9 feet below land surface, and the minimum mean of monthly mean water level for well 16MM03 for this POR is 4.8 feet below land surface. During 2020 the maximum monthly mean water level was 3.8 (February 2020) and the minimum was 4.9 (July 2020). Therefore, water levels during 2020 were close to mean levels.

2020 Drought Conditions

Groundwater levels vary depending on the amount of recharge and discharge to and from an aquifer. Precipitation affects groundwater levels because not only does it provide recharge to an aquifer, it also decreases the amount of discharge from an aquifer because the amount of pumping for irrigation is decreased. These maps from the National Integrated Drought Information system show when and where dry conditions were occurring in Georgia during 2020. Georgia received higher than average rainfall during 2020 (National Integrated Drought Information System, 2021); however, the maps show abnormally dry conditions, shown in yellow, in the southern Coastal Plain in April, more widespread across the State (mid-Coastal Plain, western part of the Piedmont, and in the Valley and Ridge/Appalachian) during July and August, and in much of the Coastal Plain and into the Piedmont at the end of 2020. There were some small areas of moderate drought during the summer months (National Integrated Drought Information System, 2021).

timeline graph of georgia drought conditions

Groundwater Resources

Contrasting geologic features and landforms of the physiographic provinces of Georgia (see map above) affect the quantity and quality of groundwater throughout the State. The surficial aquifer system is present in each of the five physiographic provinces in Georgia. In the Coastal Plain Province, the surficial aquifer system consists of layered sand, clay, and in some places limestone. The surficial aquifer system typically is under water-table (unconfined) conditions and provides water for domestic and livestock use. The surficial aquifer system is semiconfined to confined locally in the coastal area. In the Piedmont, Blue Ridge, and Valley and Ridge Provinces, the surficial aquifer system consists of soil, saprolite, stream alluvium, colluvium, and other surficial deposits.

The most productive aquifers in Georgia are in the Coastal Plain Province in the southern half of the State. The Coastal Plain is underlain by alternating layers of sand, clay, dolomite, and limestone that dip and thicken to the southeast. Coastal Plain aquifers generally are confined, except near their northern limits where the aquifers crop out or are near land surface. Aquifers in the Coastal Plain include the surficial aquifer system, Brunswick aquifer system, Floridan aquifer system, Gordon aquifer, Claiborne aquifer, Clayton aquifer, and Cretaceous aquifer system.

In the Valley and Ridge Province, groundwater is transmitted through primary and secondary openings in folded and faulted sedimentary and metasedimentary rocks of Paleozoic age. In this report, the aquifers are referred to as “Paleozoic-rock aquifers.”

In the Piedmont and Blue Ridge Provinces, the geology is complex and consists of structurally deformed metamorphic and igneous rocks. Groundwater is transmitted through secondary openings along fractures, foliation, joints, contacts, or other features in the crystalline bedrock. In this report, the aquifers are referred to as “crystalline-rock aquifers.” A more complete discussion of the State’s groundwater resources is provided in Clarke and Pierce (1985).

Selected References

Questions concerning Georgia Groundwater Conditions? Contact dwarner@usgs.gov