Water Quality Analysis - 2001

GSMNP

Work in FY 2001 was primarily focused on areas in the Great Smokey Mountains National Park (GRSM) and included field reconnaissance of ponded amphibian sites and water-quality sampling. In January, 2001, we visited with Jeff Corser, BRD, at GSNP to observe the pond sites where long-term amphibian data had been collected. Of special interest was Gourley Pond, which had experienced an amphibian die-off during the previous year. Five sites were visited including Gum Swamp, Upper Gourley Sink, Gourley Pond, Finley Cane Sinks, and The Sinks. Field reconnaissance suggested that all of the sites visited had ponded areas that were the result of solution activity in the limestone that underlies the Cades Cove portion of the park. The one exception was The Sinks (I don't know why the misnomer, the site is underlain by metamorphic rock). Gum Swamp, Gourley Pond, Upper Gourley Sink, and Finley Cane #3 are wide shallow depressions that periodically flood with surface water. Gourley Pond is different from the other three sites in that a stream has been modified such that water during high flows is diverted into the pond. The diversion structure consists of a dam constructed of local rock using no mortar and a small channel dug several feet below the surrounding land surface. I have no basis for dating the structure, but it appears old and may date back to the farming communities that lived in Cades Cove. Gum Swamp and Upper Gourley Sink appear to receive only natural runoff and direct input from rainfall.

Finley Cane #2 is a more typical karst collapse feature, with a circular shape and depth approximately twice its width. Finley Cane #2 is steep sided with limestone outcropping along the edges. The Sinks is an area that historically is believed to be an old channel for the Laurel Creek. A tremendous log jam on the river in the early 1900's was cleared by detonating explosives upstream of The Sinks. The blast was sufficiently large to remove large amounts of bedrock and divert the river's course. I am somewhat skeptical about this story in that the amount of bedrock that would have to have been removed is huge—probably the size of several houses. Regardless of its origin, the site consists of a series of pools that are amphibian habitats.

Water-quality samples were collected in April at Gum Swamp, Upper Gourley Sink, Gourley Pond, Finley Cane #3, and The Sinks. These samples show that the waters have moderate pH (4.9-6.2), low specific conductance (11.2-33 us/cm), and variable dissolved oxygen concentrations (3.9-7.7 mg/L). Dissolved ion concentrations are low and nutrient concentrations are generally low except for an elevated ammonia concentration at Finley Cane Sink (0.475 mg/L) relative to the other sites. Organic carbon was highest at Gum Swamp and Upper Gourley Sink (26.4 and 13.8 mg/L, respectively) and probably relates to the lower pH's (both 3.9) observed at these sites compared to the others. Concentrations of metals were somewhat elevated. Aluminum ranged from 19.2 to 241 mg/L and iron from 194 to 483 mg/L. Much lower aluminum concentrations were observed at Gourley Pond and may be related to the more extensive input of surface water at this site compared to the other sites. Only traces of mercury were present in the water samples. In August samples were collected at Finley Cane #2 and The Sinks. All other sites were dry. Results from the August samples are not available at this time.

For more information, contact:

W. Brian Hughes
NAWQA Chief
USGS
3039 Amwiler Rd., STE 130
Atlanta, GA 30360
E-Mail: wbhughes@usgs.gov