Groundwater Assessment Program (GAP)
Marlon Cook, Director
Groundwater Assessment Program
›› Water Facts
›› GSAGAP Information
Research Program Elements
›› GSAGAP Current Research
›› Real-time monitoring wells
›› Periodic monitoring wells
›› Scanned well records
›› Aquifer Recharge Areas of Alabama
›› Selected water-related publications by county
›› GSA on-line reports
›› Open-file Reports
Alabama Water Facts
- Seventeen major streams flow through Alabama; 10 of these have their headwaters inside the state, and the other 7 originate in other states.
- Approximately 15 percent of all surface water flowing through the lower 48 states flows through Alabama.
- Approximately 40 percent of public water supplies in Alabama are from ground-water sources. Twenty-seven of 36 south Alabama counties receive all of their public water supplies from ground-water sources.
- Alabama has 20 major aquifers that supply water from the land surface to depths approaching 3,000 feet. The deepest public water supply well is constructed in the Tuscaloosa Group aquifer in Dale County (2,750 feet).
- Alabama receives approximately 55 inches of rainfall each year, but, on average, only 6 inches move underground to become ground-water recharge.
- Since 1930, Alabama has experienced severe drought, on average, every 12 years. Each drought event lasts from one to seven years.
- A recent investigation by the Geological Survey of Alabama in Coastal Plain sediments revealed that water moves underground through the Tuscaloosa Group aquifer in southeast Alabama at 3 to 7 feet per year, and the age of the water 50 miles from the recharge area is approximately 60,000 years. If water demand is high and aquifers are relatively thin, water supply wells are not recharged rapidly enough to meet those demands. Therefore, water levels in some wells decline as much as 3 to 8 feet per year.
- In contrast, two Geological Survey of Alabama investigations in Highland Rim karst terrain indicated that water moves underground through carbonate rocks at rates of 3,000 feet per day to 4,000 feet per hour. Large quantities of water may be found in these areas. However, short residence time may cause water-quality problems related to transport of surface contaminants.
- Water exploration and development is becoming increasingly complex and in most cases requires scientific information that was once used only in oil and gas exploration or in academic research. Remote sensing, geophysical techniques, and comprehensive geochemical and stratigraphic assessments are commonly used to explore for water sources.
- Maintaining adequate supplies of clean water is critical to the high quality of life enjoyed by the citizens of Alabama. Water is necessary for maintaining agricultural production, industrial processes, power generation, and public health. As Alabama grows, the demand for clean water continues to increase.