Changes in hydrology and water quality, and initial restoration success, during the first year after construction of the Duke Forest Stormwater Improvement and Wetlands Restoration Project in the North Carolina Piedmont.
Pahl, James *,1, Richardson, Curtis1, Sutton-Grier, Ariana1, Ho, Mengchi1, 1 Duke University Wetland Center, Durham, NC, USA
ABSTRACT- Water quality in Upper Sandy Creek, a headwater for the Cape Fear River in the North Carolina Piedmont, is impaired due to high N and P, sediment load and coliform bacteria. The Duke Forest Stormwater Improvement and Wetlands Restoration Project is restoring a section of the Sandy Creek stream and floodplain within Duke Forest. The project includes the following activities: 1. Re-contour more than 600 meters of degraded stream to hydrologically reconnect the stream with the adjacent floodplain improve biogeochemical transformations to improve stream water quality (COMPLETE). 2. Build an earthen dam and 1.6-hectare (ha) stormwater reservoir to regulate stormwater delivery to downstream water bodies, replace a deteriorating dam farther downstream, and allow for additional retention and removal of excess nutrients and sediments from the stream (IN PROGRESS). 3. Build a 0.5-ha treatment wetland to intercept and improve the water quality of a tributary stream impacted by high concentrations of N and P (UNDER DESIGN). Groundwater monitoring showed that the floodplain had become hydrologically isolated from Sandy Creek, and most sites in the floodplain did not qualify as wetland. Data to be collected in 2005 will indicate whether stream re-contouring reestablished the hydrologic link between the stream and the floodplain and expanded wetland. We monitoring ambient water quality prior to stream re-contouring through September 2004. Present monitoring represents the intersession between re-contouring and dam construction. Parameters of interest include all those included in the National Sanitation Foundation's Water Quality Index (coliform, dissolved O2, BOD, temperature, pH, total dissolved solids, turbidity, nitrates, phosphates). Parameters demonstrated strong periodic trends regardless of re-contouring, which did not address delivery of stormwater to the system. Fecal coliforms were commonly in excess of NC water quality standards at all sites. Nitrates were elevated, although rarely exceeding NC standards, while phosphate concentrations were highly variable between sites and exceeded Federal standards in the upper watershed. Ambient flows of solids were minimal. We expect sampling through summer 2005 will demonstrate an increase in water quality.
Key words: floodplain restoration, water quality improvement, Piedmont stream, coliforms
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