An examination of hydrologic restoration efforts for wetland mitigation banks
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In the 1990’s, wetland mitigation banking began to emerge as an innovative method for replacing permitted wetland losses in the United States. From 1992 to 2005 the number of banks in the US increased by 780 percent and by 2008, the US Army Corps of Engineers (USACE) stated that mitigation banking would be their preferred method for wetland compensation projects required under section 404 of the Clean Water Act. While mitigation banking has become a legislative success in recent years, many agencies and wetland scientists have been concerned about the ecological success of these replacement ecosystems. While the USACE and bank sponsors monitor the initial ecological performance of the banks for five years after completion, measured standards focus almost exclusively on vegetation. However, vegetative growth is often not the most revealing indicator of ecological success in a wetland restoration project’s nascent years. A wetland’s hydrologic system is the primary driving factor in its development, determining both the abiotic and biotic conditions and its future ability to sustain itself. Therefore, effectively restructuring a site’s hydrologic conditions is a critical component to its ultimate success as a replacement wetland ecosystem, but this crucial factor is generally not evaluated as part of mitigation bank monitoring. I have therefore focused this dissertation on design and performance principles important for creating and measuring functional hydrology in wetland mitigation banks by: 1) developing a checklist of hydrologic restoration standards based on the most current literature; 2) examining how closely bank sponsors followed these hydrologic principles throughout the design and development stage of their mitigation bank projects by reviewing the publicly available data on the USACE website; and 3) producing an example site design in which I show how a potential mitigation bank can be designed according to the hydrologic principles proposed in the literature review.