Water Quality of Episodic Flow through Isolated Wetlands Embedded in a Long Leaf Pine / Wiregrass Ecosystem

Isolated, depressional wetlands are common on the karstic Dougherty Plain in Southwest Georgia, where dissolution of the underlying limestone has resulted in a landscape that is largely devoid of headwater streams. Stormwater runoff collects in these wetlands, and occasionally spills into perennial streams following major storms. In this study, we report water-quality data collected during a three-week stormflow event (Feb 15 to Mar 9, 2014) which resulted from over 203 mm of precipitation between February 13th and March 5th, 2014. Data were collected along two flowpaths at the Joseph W. Jones Ecological Research Center, a private, 11,700-ha property on the Dougherty Plain of southwest Georgia. Sampling of both flowpaths began where upstream agricultural stormflow first enters the site. Inflows plus additional onsite contributions were then monitored as they migrate across the forested site through and between normally isolated wetlands. A suite of physical water quality parameters, nutrients and pathogen indicators (total coliform, E. coli) were monitored daily at 5 sites along the first flowpath, and at 2 sites along the second flowpath. A general trend of decreasing sediment, nutrient, and pathogen concentrations was observed as water moved between and through isolated wetlands. The mechanisms producing these results are unclear but are probably attributed to a combination of dilution from soil water/upland runoff and biogeochemical activity/sedimentation.