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Detention ponds are currently accepted as stormwater best management practices (BMPs) in coastal South Carolina. These ponds are typical catch basins for stormwater piped directly from impervious surfaces in many residential and resort areas. Nutrients often concentrate in the ponds and contribute to eutrophication within the ponds and downgradient estuaries. A supplementary BMP is proposed that would augment nutrient attenuation in these urbanized watersheds and subsequently reduce the potential for nutrients to enter adjacent estuaries. A created wetland was designed to border an existing detention pond on Kiawah Island, SC, providing a vegetated buffer with increased retention time for stormwater flows from upland residential and recreational uses toward ecologically sensitive receiving estuarine waters. The overall objective of the project was to determine the feasibility of a created wetland as a retrofit option. The unique design incorporates aspects of both subsurface and surface-flow constructed wetlands for processing nutrient-enriched stormwater and groundwater, focusing on encouraging denitrification for the reduction of nitrate fluxes into the detention pond. For hydrologic evaluation, a continuous water balance model was developed using STELLA software to determine the hydrologic capacity and stormwater management potential of two selected wetland designs. This paper describes the evaluation process and assesses the design concept in terms of stormwater management.