Effects of the Chickasawhatchee Swamp on Surface-Water Quality

Research Team: Dr. Stephen W. Golladay (Associate Scientist), Juliann M. Battle (Research Technician III), and Raynie Bambarger (Research Technician)

Since 1994, surface-water samples have been taken monthly during stable flow periods at the base of the three major subcatchments (Pachitla Creek, upper Ichawaynochaway Creek ‑ near Morgan, and Chickasawhatchee Creek) in the Ichawaynochaway Creek drainage. The catchments ranged in size from 65,800 to 86,800 ha. Row-crop agriculture and managed forestlands are the dominant land use within each catchment. Pachitla Creek and upper Ichawaynochaway Creek catchments had very similar land use. Chickasawhatchee Creek had 10‑13% less agriculture and greater wetland area than the other sites. Urban development was minimal in each of the three catchments. Median concentrations of several water quality constituents were different among sites. Chickasawhatchee Creek had significantly lower suspended sediment and nitrate than either of the other sites. Dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) concentrations in Chickasawhatchee were significantly greater than the other sites. Particular organic matter concentrations and possibly nitrite concentrations were lower in Chickasawhatchee Creek than at least one of the other streams. There was no difference in soluble reactive phosphorus concentrations between streams.

Alterations in stream water quality are often associated with human land use within catchments. In particular, conversion of natural vegetation to agriculture, silviculture or other uses increases inorganic nitrogen and suspended sediment concentration. Elevated concentrations can result from increased erosion, reduced plant uptake, increased transport, and fertilizer application. By acting as filters, floodplain wetlands and swamp forests can partially offset runoff from human dominated uplands and are important in preserving water. While lower than the other sites, the Chickasawhatchee catchment has considerable human land use. Yet, inorganic nitrogen concentrations and suspended sediment concentrations in Chickasawhatchee Creek downstream from the Chickasawhatchee Swamp were lower than the other sites. This suggests that the swamp may be an important buffer preserving water quality in southwest Georgia.

In addition to its role in preserving water quality, the Chickasawhatchee Swamp may also provide important ecological functions within the region. Swamp forests are noted for their high productivity. A portion of this productivity, litterfall, is seasonally deposited on floodplain soils. Litterfall is then partially degraded by microbial activity and a portion is exported during seasonal flood pulses. Exported organic carbon is an important food resource for aquatic communities downstream. High DOC concentrations observed in Chickasawhatchee Creek suggest substantial export of organic carbon from the swamp. Aquatic productivity in Chickasawhatchee Creek, lower Ichawaynochaway Creek and the Flint River may be dependent on swamp derived carbon export.

Greater DIC concentration in Chickasawhatchee Creek suggests a stronger hydrologic connection to the Upper Floridan aquifer than the other streams. At present the degree of connection to the aquifer, and the role of the swamp in regional hydrology has been largely uninvestigated.

If it is determined that the swamp is playing a role in preserving or improving water quality, it will justify greater wetland protection both within the Chickasawhatchee catchment and the region. If aquatic productivity is higher downstream of the Swamp, this can also be used to justify greater wetland protection within the region. Understanding the Swamp's hydrologic role is critical in the development of regional water allocation plans.

Following are specific elements of this component of the project:

Expand the current long-term monitoring network to include the major tributaries to the Swamp (upper Chickasawhatchee, Kiokee, and Spring Creeks).
Quantify the water quality in the tributaries entering the Swamp.
Evaluate the effectiveness of the water-quality mitigating capacity of the Swamp.

Research in progress, publications forthcoming.

Funded by: The Joseph W. Jones Ecological Research Center