Modeling and Cost-Benefit Analysis of Restoration Alternatives for the Lakefield Watershed

Abstract

The Lakefield Watershed is one of the densest urban areas in all of Rockdale County. Large volumes of runoff and heavy pollutant loads from the landscape have degraded water quality, stream channels, and overall habitat conditions in downstream watersheds. Within the Lakefield Watershed, there are a limited number of best management practices (BMPs) that treat stormwater runoff; many of these are undersized or improperly designed. At the downstream terminus of the watershed, a small lake (approximately 4 acres) provides water quality benefits and some peak flow attenuation through regional detention. However, the lake is impounded by a Category I dam (probable loss of life and property upon failure) that is not in compliance with the rules of the Georgia Safe Dams Act. A study was initiated to determine whether rehabilitating the existing dam and retrofitting the existing lake or retrofitting existing upland BMPs combined with new BMPs or low impact development techniques was the most cost-effective means to achieve water quality and channel protection for the watershed. There were significant drivers for rehabilitating the dam including life and safety issues, economic development in the region, and transportation improvements through construction of a bypass road across the dam. The results of the study showed that due to the built-out nature of the watershed and the insufficiency of existing BMPs, that rehabilitating the existing dam was the most cost effective means to meet the stated objectives.