ISIS ecosystem restoration feasibility study

Abstract

Tetra Tech is supporting the United States Army Corps of Engineers (USACE) Mobile District and DeKalb County in a feasibility study for ecosystem restoration in the Sugar and Snapfinger Creek watersheds in DeKalb County, Georgia. Flashy hydrology, resulting from urban development, has caused excess bank erosion and sedimentation in the streams. The feasibility phase of this study involved baseline biological monitoring, hydrologic modeling, selection of potential management measures, and analysis of project alternatives. Over 100 potential management measures were evaluated, and selected measures were strategically combined into alternative plans. Environmental benefits of alternative plans were evaluated using the Ecosystem Response Model which was developed in a collaborative effort by North Georgia Water Resource Agencies (NGWRA) to quantify environmental quality for USACE studies around North Georgia. The proposed measures were selected to reduce peak flows, improve physical habitat conditions and biotic communities in the stream systems, and improve riparian and floodplain functions. The process of evaluating alternatives for this study revealed that the greatest benefit to the overall watershed was provided by measures placed in the headwaters and by large flow attenuation features that can significantly reduce peak flows.