When you drill a well in the Suwannee River Basin, what water do you get?

Early settlers could dig a well by hand 20-40 feet deep and get enough water. That’s the Surficial Aquifer, which is groundwater in sandy soils near the surface, below the water table. That’s not so easy now, after decades of agricultural and industrial well pumping.

Drill deeper and you’re into the Upper Floridan Aquifer, which is water in cracks and caverns in karst limestone. Or that aquifer may reach to the surface in a spring, as in a few spots in south Georgia and many in north central Florida.

Or the ground may collapse into the aquifer, in a sinkhole. How often do sinkholes happen, and under what conditions? Well, we don’t know in Lowndes County, Georgia, because the county has never studied it. I don’t know of any other counties that have studied this problem. Alachua County, Florida, at least has a factsheet.
https://alachuacounty.us/Depts/EPD/Documents/Natural/sinkhole%20fact%20sheet%20062112.pdf
But it doesn’t seem to reference any systematic study.

Few wells go deeper than the Upper Floridan Aquifer, but there is also a Lower Floridan Aquifer, and in some places, more aquifers even below that.

Surficial Aquifer, Upper Floridan Aquifer, Sinkholes and Springs, Lower Floridan Aquifer

These figures are from USGS Professional Paper 1807, Revised April 8, 2015, “Revised Hydrogeologic Framework of the Floridan Aquifer System in Florida and Parts of Georgia, Alabama, and South Carolina,” by Lester J. Williams and Eve L. Kuniansky.

http://pubs.usgs.gov/pp/1807/

How deep? In Lowndes County, maybe 100 feet deep, maybe less, and you’re into the Upper Floridan Aquifer.

In Irwin County, Georgia, where a hyper-scale AI datacenter has been permitted, anywhere from almost zero to 200 feet, depending on where. Continue reading →