Legacy Disturbances and Restoration Potential of Coastal Plain Streams

Stream restoration and enhancement provides opportunity to correct or improve previous alterations that have destroyed, diminished, or impaired the character and function of stream systems. The Savannah River Site (SRS), a National Environmental Research Park operated by the Department of Energy, provides an ideal research opportunity for restoration of coastal plain streams. The temporal range of disturbances to SRS streams span the range of pre-SRS legacy impacts through the early infrastructure development in the early 1950's to more recent and current industrial activities. A multiphase program has been established to characterize SRS streams, identify risks of legacy and recent disturbances, and identify disturbed stream reaches with potential for restoration. Three levels of assessments are being conducted, with detail increasing with each level. A Level I assessment involves a broad scale survey of potential stream disturbances and stream basin characterization. Our surveys are identifying streams that represent a broad disturbance gradient ranging from severely altered streams to the best available reference systems. The least disturbed streams are critical to establish an endpoint model system. We are identifying drainage basins where contiguous high-quality watersheds could be established. We are documenting flow impediments such as active and abandoned dams, road and railroad crossings, and utilities cuts. Severe erosion, incision, and sedimentation from historical and present land use, outfalls, roads, railroads, utilities cuts, and abandoned borrow pits are being recorded. Pathways of outfalls and runoff from industrial areas reaching perennial or intermittent streams are being mapped. Disturbances are being placed into a temporal context to establish whether of pre-SRS or SRS origins. Perennial and intermittent streams are being field delineated and detailed maps created using LiDAR imagery. A series of basin characteristics are being measured for each tributary basin. A Level II assessment, initiated in 2010, is assessing the effects of stream alterations in a subset of streams identified in the Level I survey. Stream hydrology, geomorphology, and habitat availability at the reach, segment and basin level are being assessed. To date, a total of 48 sites representing a gradient of disturbances that occurred from pre-SRS to current have been included. Our protocol draws upon field measurements as well as additional GIS analyses. A Level III assessment will further evaluate a selected subset of stream reaches by measuring additional hydrology, physicochemistry, and geomorphology features. This comprehensive stream evaluation will provide management options and guide prescriptions for potential restorative actions.