Landscape characteristics of a stream and wetland mitigation banking program

Abstract

In the United States, stream restoration is an increasing part of environmental and land management programs, particularly under the auspices of compensatory mitigation regulations. Markets and regulations surrounding stream mitigation are beginning to mirror those of the well-established wetland mitigation industry. Recent studies have shown that wetland mitigation programs commonly shift wetlands across space from urban to rural areas, thereby changing the functional characteristics and benefits of wetlands in the landscape. However, it is not yet known if stream mitigation mirrors this behavior, and if so, what effects this may have on landscape-scale ecological and hydrological processes. This project addresses three primary research questions. (1) What are the spatial relationships between stream and wetland impact and compensation sites as a result of regulations requiring stream and wetland mitigation in the State of North Carolina? (2) How do stream impacts come about due to the actions of different types of developers, and how do the characteristics of impacts sites compare with compensation sites? (3) To what extent does stream compensation relocate high-quality streams within the river network, and how does this affect localized (intrawatershed) loss or gain of aquatic resources? Using geospatial data collected from the North Carolina Division of Water Quality and the Army Corps of Engineers' Wilmington District, we analyzed the behavior of the North Carolina Ecosystem Enhancement Program in providing stream and wetland mitigation for the State of North Carolina. Our results suggest that this program provides mitigation (1) in different ways for different types of permittees; (2) at great distances (both Euclidean and within the stream network) from original impacts; (3) in significantly different places than impacts within watersheds; and (4) in many cases, in different watersheds from original impacts. Our analysis also reveals problems with regulator data collection, storage, and quality control. These results have significant implications given new federal requirements for ecological consistency within mitigation programs. Our results also indicate some of the landscape-scale implications of using market-based approaches to ecological restoration in general.