Management of a restored wetland: challenges and lessons associated with the nutrient reduction potential of Beaver Creek Wetland in Grand Lake St. Marys Watershed

Abstract

Wetlands are becoming increasingly used as tools to help watersheds mitigate nutrient runoff as part of efforts to reduce the frequency of harmful algal blooms. Wetland restoration is needed given that the majority of these habitats have been lost to development/draining efforts on a global scale over the past few centuries. The objective of this study was to monitor nutrient reductions achieved with the restored (constructed in 2017) Beaver Creek Wetlands in the Grand Lake St. Marys Watershed (Ohio) as a result of active management incorporating communication and data driven decision making among collaborators as part of efforts to curtail runoff. A hydrologic budget was created by collecting flow measurements coupled with water samples collected weekly from 2018–2024 at the Stream Inflow and Wetland Outflow that were then analyzed for nutrients (SRP, TP, NO3-N) and sediment (TSS). As a result of active management, the wetland was able to capture approximately 1.2% (108 million m3) of the total Beaver Creek flows over the monitoring period and reduce the total SRP, TP, NO3-N, and TSS loads of captured water by 78.4%, 78.1%, 95.7%, and 87.5%, respectively. Nutrients were removed at an average rate of 2.2, 3.8, 135, and 416 g/m2/yr for SRP, TP, NO3-N, and TSS, respectively, while only occupying a 0.23% footprint in the subwatershed. Despite these successes, however, GLSM remains hypereutrophic largely resultant of still untreated tributary loading flowing into the lake–thus, this study reinforces the importance of continued wetland restoration and management for meeting overarching nutrient reduction goals.