We all drink with straws from the groundwater here in the U.S. southeast coastal plain.

River water and groundwater interchange interacts with drinking water treatment in Georgia and Florida

So surface water interchange with groundwater produces problems for city and county drinking water treatment, and for E. coli contamination of private water wells.

Figure 1. Generalized cross section in the Suwannee River basin showing karst features that facilitate the exchange of water between the surface and subsurface.
from The Suwannee River Basin Pilot Study: Issues for Watershed Management in Florida, U.S.G.S.

This is not just some theoretical matter. Withlacoochee River water going into Shadrick Sink west of the river, then under the river and miles east, forced the city of Valdosta to sink its water wells twice as deep.

Shadrick Sinkhole, 30.9039270, -83.3135440 in Shadrick and Cherry Creek Sinks on the Withlacoochee River near Valdosta, 2015-02-18.

Sustainability of Ground-water Resources, by William M. Alley Thomas E. Reilly O. Lehn Franke, 1 January 1999, U.S. Department of the Interior, U.S. Geological Survey – Publisher. In Box E on Page 63:

The Connection Between Surface-Water Quality and Ground-Water Quality in a Karst Aquifer

Figure E-1. Estimated percentage of Withlacoochee River water in ground water in the Upper Floridan aquifer, June 1991. (Modified from Plummer and others, 1998.)

The Upper Floridan aquifer, which is the sole source of water supply for Valdosta, Georgia, and much of the surrounding area, receives large volumes of direct discharge from the Withlacoochee River through sinkholes in the streambed or off-channel. A highly interconnected conduit system has developed in the Upper Floridan aquifer in this area, which extends at least 15 miles from the sinkhole area. Chloride and isotopic data were used by Plummer and others (1998) to map the percentage of Withlacoochee River water in ground water in the Upper Floridan aquifer (Figure E-1). These data indicate that ground water in parts of the Upper Floridan aquifer contains high percentages of recently recharged Withlacoochee River water. Plummer and others (1998) note that, although the patterns shown in Figure E-1 are generally true over the area, extreme variations can occur at a given location, as would be expected because of the large variations and discontinuities in hydraulic properties in the karst environment and time-varying inflows of river water into the aquifer.

Sinkhole near the Withlacoochee River. (Photograph by Richard E. Krause, U.S. Geological Survey.)

The strong connection between the Withlacoochee River and ground water in the Valdosta area has created concerns about the potential for contamination of ground-water supplies by contaminants in the river. There also are concerns about the effects of natural organic matter in the river water. For example, in the early 1980’s, it was recognized that chlorination of aquifer water produced disinfection by-products in excess of drinking-water standards. This occurred as a result of reaction of chlorine with the high amounts of natural organic matter in the river water recharged to the aquifer.

The original wells for Valdosta were near the city, in the areas where the aquifer contains a high percentage of river water. The city completed a new set of water-supply wells in the well field indicated in Figure E-1, in an area where the aquifer contains a relatively low percentage of river water. Even with this added level of assurance, it is still necessary to protect the surface waters that supply the aquifer. The source area of concern for ground water is the entire Withlacoochee River Basin upstream from Valdosta.

Lowndes County has its own water and sewage systems, separate from Valdosta’s. Lowndes County has long had to deal with the same issue of river water in water wells, coming from both the Withlacoochee River and the Alapaha River.

At its recent (March 5-7, 2025) Annual Planning Meeting, the Lowndes County Commission considered a suggestion from its Utilities Department for more expensive nanofiltration:

• Spring Creek Water Treatment Plant
  • This project includes construction of a new well and a Nanofiltration water treatment plant.

Spring Creek Well Tank, Lowndes County, GA –Google Streetview

Lowndes County Utilities spelled out the problem:

WATER TREATMENT CHALLENGES

The water source for Lowndes County is the Floridan aquifer, a large underground water body embedded in limestone hundreds of feet below the ground surface. The aquifer is expansive and covers parts of Georgia, Alabama, South Carolina, and all of Florida.

There are areas in Lowndes County along the Withlacoochee and Alapaha Rivers where the river waters seep through fractures in the limestone allowing naturally occurring organic matter in the rivers to reach the Floridan aquifer. Groundwater in these areas is referred to as “groundwater under direct influence” (GWUD)) of surface water.

When public drinking water wells are drilled into these areas, there are often problems where the naturally occurring organics react with chlorine injected into the water system for disinfection purposes resulting in the formation of trihalomethanes (TTHMs) and halo-acetic acids (HAAs). These chemical compounds at certain concentrations and temperatures in drinking water can be health hazards.

The significance of this is that organic levels in some of the County’s water supply wells are causing exceedances of the allowable amounts of TTHMs and HAAs as set by the US EPA. To come into compliance requires additional treatment beyond the traditional methods used in Lowndes County for several years.

To address the exceedances, the Utilities Department has conducted pilot studies on several treatment methods for removing the organics in the groundwater including blending, advanced ion exchange (MIEX), ultrafiltration, peroxide, and nanofiltration. The only consistently effective process for removing the organics was nanofiltration. Based on these results, the Utilities Department will move forward with planning for nanofiltration plants for the Spring Creek well site on Hattie Place and at the Alapaha Plantation Subdivision Water Treatment Plant during 2025.

Readers, please note: the county wrote “injected into the water system” as in into the drinking water system. They do not inject anything into the groundwater.

This is not just an issue for Valdosta, or Lowndes County, or Georgia.

Downstream on the Withlacoochee River in Madison and Hamilton Counties, Florida, there is much concern about contamination of Withlacoochee River Water potentially leaching through groundwater into private wells. See, for example, Well testing results, Madison County, FL, after Valdosta sewage spill 2020-01-03.

Florida has even more sinkholes and springs than south Georgia, and underground water also moves sideways all over the Floridan Aquifer.

Figure 60 Map showing potentiometric contours and ground-water movement in the Floridan aquifer system in 1980 (608K), in GROUND WATER ATLAS of the UNITED STATES: Alabama, Florida, Georgia, and South Carolina, HA 730-G, Floridan aquifer system

The North Florida Regional Water Supply Plan, despite its flaws, demonstrates that local water supplies are affected by withdrawals far away, including in Jacksonville and Savannah.

Figure C3: Aquifer surface change due to withdrawals in north Florida and south Georgia
in Less withdrawals, more water retention for North Florida Regional Water Supply Plan, 6 December 2016″>

The direction of water flow into or out of the ground can depend on aboveground water levels. See for example the Little Alapaha River, which usually disappears into a complex of swallets (exposed windows into the underlying aquifer), yet may sometimes flows all the way to the Alapaha River, and in February 2022 we witnessed absorbing Alapaha River water, making the Little Alapaha River a distributary, presumably taking that water into sinkholes or swallets into the aquifer.

Helen Crowley turning around in the Little Alapaha, 2022-02-05, 11:07:46, 30.5013830, -83.0383300
in Little Alapaha River, Swallet, Bridges, Source, Mouth 2022-02-07.

This is in addition to the well-known Dead River Sink, which takes water from the Alapaha River via the Dead River, so much during much of the year that the last 19 miles of the Alapaha River are dry.

Gretchen Quarterman, Dead River Sink, 2021-11-07, 15:33:34, 30.5820036, -83.0516436
in Pictures: Dead River Sink 2021-11-07.

We witnessed the Dead River Sink dye test on June 22, 2016, by people from FDEP and SRWMD.

Tom Greenhalgh dying the Dead River, Harley Means, and a drone, 2016-06-22

A few days later, the water came back up at the Alapaha River Rise and Holton Creek Rise, two springs on the Suwannee River.

Figure 1. Study area and field sites
PDF
in Alapaha Swallets Dy Trace Project, By Tom Greenhalgh, P.G. 1277, and Karlee Fowler, October 2016.

Alapaha River Rise, 2022-02-05, 14:19:24, 30.4388490, -83.0895792
in Pictures: Last stretch, Alapaha River 2022-02-05.

Such swallets also occur on the Withlacoochee River in Florida, such as Sullivan Slough and Sink. That Sink appears to actually be a swallet, sometimes discharging water into the river, and sometimes absorbing it, like the afore-mentioned Shadrick Sink in Georgia.

Sullivan Slough, 2022-06-04, 14:50:33, 30.4929739, -83.2436478
in Pictures: Florida Campsites to Allen Ramp, Withlacoochee River 2022-06-04.

More recent USGS research also finds salt water moving in layers among the fresh water. We sure don’t need sewage or chicken manure or coal ash or pipeline leakage or drilling fluids or fracking waste added to that mix.

Figure 26 Waste Water Treatment Plant (AFFF Area 8) PFBS, PFOA, and PFOS in Groundwater and Surface Water
in Final Site Inspection Report of Fire Fighting Foam Usage at Moody Air Force Base Lowndes County, Georgia, December 2016, for Air Force Civil Engineer Center and USACE by Aerostar SES LLC.

Or PFAS forever chemicals.

 -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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