University of Georgia (UGA) Professor Todd C. Rasmussen is back after 30 years with peer-reviewed double evidence that the Okefenokee Swamp does exchange water with the underlying Floridan Aquifer from which we all drink in south Georgia and north Florida.

Okefenokee Swamp leaks water into the Floridan Aquifer –peer-reviewed evidence 2025-12-09, Mining withdrawals would make it worse

This paper is more incentive to pass Georgia House Bill 561 to protect the Okefenokee Swamp from mining, at least on its east side. Georgians, please ask your statehouse delegation to pass HB 561. Floridians, please ask your Georgia friends and relatives to do the same. Here’s how to contact Georgia Statehouse members:

https://wwals.net/about/elected-officials/georgia-house/

Here’s a video explaining the new paper by its first author Prof. Jaivime Evaristo, on YouTube, 2025-12-09, The Okefenokee is Not a Bathtub: A New Look at Wetland-Aquifer Coupling,

https://www.youtube.com/watch?v=LE3lEytxz0o

See also Drew Kann, Atlanta Journal-Constitution, 15 December 2025, Would Okefenokee mining affect a key aquifer? Likely yes, new study finds.
Researchers found groundwater withdrawals near the Okefenokee for mining or other activity could lower water levels in the swamp.

In this post I’m going to provide a bit of context and hit some high points of the new paper.

Before Twin Pines Minerals (TPM) got bought out, among their application materials for permits to strip mine with 3 miles of the Okefenokee Swamp were figures demonstrating that their water withdrawals would cause a cone of lowered aquifer levels under the swamp.

Figure 8. Drawdown 2930 days

As the new paper indicates, and Prof. Evaristo’s video points out, water withdrawals from the aquifer draw more water from the swamp into the aquifer.

These independent lines of evidence confirm that the swamp and aquifer are hydraulically connected through a semi-confining system. Vertical leakage from the swamp may represent 5%-15% of annual rainfall and contributes to the isotopic enrichment of UFA waters downgradient.

If the swamp dries out, even in parts, various things that have been collecting in it, such as mercury from coal plants, can also be drawn into the aquifer.

Why it Matters, 2025-12-09 –Jaivime Evaristo

Aquifer water also moves sideways, including southwest from the Swamp into north Florida. The North Florida Regional Water Supply Plan (NFRWSP), prepared by Florida’s Suwannee River Water Management District (SRWMD) and St. Johns River Water Management District (SRWMD), using the North Florida-Southeast Georgia (NFSEG) regional groundwater flow model, examined effects of pumping by Savannah, Georgia, and Jacksonville, Florida, on south Georgia and north Florida. While flawed, the NFRWSP does indicate the widespread geographical implications of water withdrawals. Pumping by Jacksonville and Tallahassee have already lowered aquifer levels across North Florida, and pumping around Savannah even more so.

Figure C3: Aquifer surface change due to withdrawals in north Florida and south Georgia

So water drawn into the aquifer because of mining withdrawals could affect drinking water downhill in Florida as well as Georgia. And such water could affect springs and rivers, in levels, flows, and content, Suwannee River Basin, including the Santa Fe River Basin, with the Ichetucknee River.

Back in 1995, UGA Professor Todd C. Rasmussen and his graduate student Susannah Kitchens published preliminary evidence of this surface and groundwater interchange. Their conference paper demonstrated that the underground level of the Floridan Aquifer increases about a month after the level of the Okefenokee Swamp increases.

HYDRAULIC EVIDENCE FOR VERTICAL FLOW FROM OKEFENOKEE SWAMP TO THE UNDERLYING FLORIDAN AQUIFER IN SOUTHEAST GEORGIA, 1995-04-11 –Todd C. Rasmussen and Susannah Kitchens
PDF

Even back then, they were able to issue a warning, “Such a large loss of water from the swamp may be responsible for observed pH and water level changes, and increased heavy metal accumulations in aquatic organisms in the swamp.”

Now in 2025, Prof. Rasmussen is back with more evidence. He and UGA Professors C. Rhett Jackson and Jaivime Evaristo in December published a peer-reviewed paper confirming the month lag in underground water levels, and getting more specific about how much water. They used two independent lines of evidence that the swamp and aquifer are vertically connected.

Not so Isolated: Isotopic and Hydraulic Evidence of Vertical Connectivity Between the Okefenokee Swamp and Floridan Aquifer, 2025-12-09, Jaivime Evaristo, C. Rhett Jackson, Todd C. Rasmussen
PDF

This result is different from the previous assumption that the limestone rocks under swamp and above the aquifer would prevent water moving up and down between surface and aquifer. Those rocks, the Hawthorn Formation, are actually riddled with cracks that permit water to move through them. The three UGA Professors’ new paper demonstrates that. As the first author’s video puts it, the Hawthorn Formation is not a sealed bathtub, more like a leaky pool.

Their paper indicates that this vertical water mobility is not unique to the Okefenokee Swamp:

Although deep aquifers often contain “fossil” water recharged during the late Pleistocene, half of such wells worldwide also contain tritium, indicating partial mixing with modern recharge (Jasechko et al 2017).

Tritium is an indicator because it is usually produced as a side-effect of nuclear power plants or atmospheric nuclear testing, neither of which existed before 1945.

They note that human well pumping can alter underground water composition:

Intensive groundwater pumping further deepens this penetration: across U.S. aquifers, modern water reaches greater depths where withdrawals are highest, showing that pumping can draw young, contaminant- prone water downward into previously isolated zones (Thaw et al 2022).

So even if the Hawthorn Formation does restrain some vertical flow, overpumping or mining could alter that:

Thus, thick confining units do not guarantee isolation; preferential pathways and hydraulic stresses can short-circuit stratified systems.

In this new paper, the three professors built on work by others that demonstrated that isotopes of water show that surface water does get into aquifer water, especially where there are wells drawing water out of the aquifer and thus pulling water downward into the aquifer.

Previous studies did not directly examine the Okefenokee Swamp. This one does.

In addition to new water isotope measurements from swamp waters and nearby wells, the new paper analyzes “multi-year records of swamp stage and groundwater heads.” This pair of approaches allows the three professors to demonstrate that the swamp does leak into the aquifer in spots, in different amounts at different times, and nearby pumping can increase those amounts.

The amount the swamp leaks into groundwater is not small:

Isotopic mixing models indicate that up to 92% of groundwater beneath the swamp is swamp-derived, and hydraulic response analysis yields a vertical diffusivity of ~291 m2/d, consistent with monthly-scale signal transmission across a semi-confining layer.

The warning of this new research is clear: water withdrawals near the Okefenokee Swamp, such as for strip mining, can draw swamp water into the Floridan Aquifer. It seems likely that such pumping could also draw surface water on the mine site into the aquifer. From either source, the surface contaminants carried by that water would then also travel sideways into south Georgia and north Florida.

We all drink from the Floridan Aquifer. Mining for titanium dioxide for white paint is not worth risking the Okefenokee Swamp or our drinking water.

Please help pass HB 561 as the least we can do to prevent further strip mining attempts.

References

Kitchens S, TC Rasmussen (1995), Hydraulic evidence for vertical flow from Okefenokee Swamp to the underlying Floridan Aquifer in Southeast Georgia. 1995 Georgia Water Resources Conference, Proceedings, Athens GA, p. 156-157.
https://toddrasmussen.droppages.net/pubs/GWRC1995a.pdf

Jaivime Evaristo, C. Rhett Jackson, Todd C. Rasmussen (2025), Not so isolated: isotopic and hydraulic evidence of vertical connectivity, Environmental Research Water,
https://doi.org/10.1088/3033-4942/ae2653

 -jsq, John S. Quarterman, Suwannee RIVERKEEPER®

You can help with clean, swimmable, fishable, drinkable, water in the 10,000-square-mile Suwannee River Basin in Florida and Georgia by becoming a WWALS member today!
https://wwals.net/donations/

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