Coweeta Groundwater Monitoring and Research Station

Coweeta is located within the Blue Ridge geologic belt (fig. 1), and is characterized by rugged, often steep terrain. The portion of the basin being investigated as part of REP is located in the low lying floodplain (about 2100 feet above mean sea level) near the confluence of Ball Creek and Shope Creek (well cluster 1), in the midslope area of Ball Creek (well clusters 2 and 3, at elevations of about 2700 and 2800 feet above mean sea level, respectively), and at a high elevation area (well cluster 4, elevation of about 3800 ft above mean sea level)(fig. 2). This area is underlain by moderately foliated, Precambrian-age muscovite-biotite gneiss, metasandstone and quartz-feldspar gneiss, and lesser amounts of interlayered pelitic schist and quartzite. Contacts with well-foliated biotite garnet schist and massive, poorly foliated quartz diorite gneiss also occur in the study area. The stream valleys in this area are underlain by unconsolidated alluvium and colluvium.

The primary objectives of the hydrogeologic investigation are to: (1) characterize the groundwater geochemistry in a pristine, mountain setting underlain by felsic gneiss and evaluate changes over time and space within the local groundwater system; (2) evaluate the hydraulic communication between the shallow regolith and deeper bedrock flow systems and the local flow dynamics between ground and surface water in both recharge and discharge areas; (3) evaluate the regolith-bedrock transition zone and its role as a preferential groundwater flow pathway; (4) characterize aquifer properties in the regolith and bedrock in selected areas; (5) determine the age of groundwater and time of travel from a recharge area to a discharge area; and (6) track water level fluctuations over time, in response to fluctuations in evapotranspiration, rainfall, and seasonal climate.

The Coweeta hydrogeologic research station consists of 4 well clusters, a stream gage, and 2 rain gages. Each well cluster generally consists of three wells open to different zones within the groundwater system: upper regolith, lower regolith, and fractured bedrock. The well nests are spaced 1500 to 5000 feet apart and represent areas of recharge and discharge. Numerous tests are being conducted on water quality, groundwater movement, and hydrogeologic setting, including various water quality analyses, groundwater age dating, oriented borehole geophysical surveys, water level measurements, continuous temperature measurements, aquifer tests, and others. The gage, wells, tests, and analyses are being used to evaluate groundwater availability, movement, and quality in a regolith-fractured rock flow system dominated by felsic gneiss geology.

Mean annual precipitation in the basin is about 96 inches, well greater than most other areas of Western North Carolina. Groundwater discharge occurs along Ball Creek and its tributaries. Gage records exist back to about 1946 for two locations along Ball Creek within the study basin. Ball Creek flows into Coweeta Creek, which in turn empties into the Little Tennessee River. The Tennessee River is a tributary of the river network that includes the Ohio River and the Mississippi River, which ultimately empty into the Gulf of Mexico.