The Morphology of Streams Restored for Market and Nonmarket Purposes: Insights from a Mixed Natural-Social Science Approach

This analysis uses geomorphic surveys to quantify the differences between restored and nonrestored streams as well as the differences between streams restored for market purposes (compensatory mitigation) and those restored for nonmarket programs. In addition, it examines the social and political-economic drivers of the stream restoration and mitigation industry using policy documents and interviews with key personnel, including regulators, mitigation bankers, stream designers, and scientists. Among the findings: Restored streams are typically wider and geomorphically more homogenous than nonrestored streams. Streams restored for the mitigation market are typically headwater streams and are part of a large complex of long restored main channels and many restored tributaries; streams restored for nonmarket purposes are typically shorter and consist of the main channel only. Interviews reveal that designers integrate many influences, including economic and regulatory constraints, but traditions of practice have a large influence as well. Thus, social forces shape the morphology of restored streams.