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The Stream Quantification Tool and its Application for Stream Mitigation and Impact Determination

Workshop Co-leads: Cidney Jones, EPR
Julia M. McCarthy, EPA Region 8
Aaron Eilers, USACE Omaha District
Matt Montgomery, USACE Sacramento District

The U.S. Army Corps of Engineers (USACE) and U.S. Environmental Protection Agency (EPA) have developed a new approach to stream assessment and crediting/debiting to inform permitting decisions under the Clean Water Act Section 404 permitting program in Wyoming and Colorado. The approach includes a consistent suite of metrics to characterize functional lift at restoration sites and functional loss at sites with permitted impacts. The Colorado and Wyoming Stream Quantification Tools (CSQT and WSQT, respectively) are an outgrowth of the 2012 publication, A Function-Based Framework for Stream Assessment and Restoration Projects. This framework organizes stream functions into five functional categories (hydrology, hydraulics, geomorphology, physicochemical, and biology) and outlines parameters, measurement methods, and performance standards that can be used to determine stream functional capacity within each category. In 2014, the Environmental Defense Fund and Stream Mechanics developed a stream quantification tool built on the concepts in the Stream Functions Pyramid Framework. The tool calculates the difference in an existing and proposed stream condition at the function-based parameter, functional category, and overall reach levels. The EPA, USACE and interagency review team partners in Wyoming and Colorado have regionalized this tool for use in these western states. The Wyoming Stream Quantification Tool version 1.0 was released for use in the Clean Water Act Section 404 permitting program in Wyoming in 2018 while the Colorado Stream Quantification Tool Beta Version will be released for public comment in 2019.

 This workshop will include:

An overview of the Stream Functions Pyramid Framework and the Colorado and Wyoming Stream Quantification Tools, information on how the tools can be used to develop function-based project goals and objectives, select quality project sites based on restoration potential, and develop assessment approaches, monitoring plans and performance standards that align with project goals and objectives.

An overview of stream mitigation procedures, and how the agencies intend to use the outputs of the Stream Quantification Tools to calculate functional loss from permitted impacts (debits) and functional lift from mitigation or restoration activities (credits).

 The target audience for this workshop includes regulators, practitioners and any other entities doing work related to CWA Section 404 permitting. Students will receive notes and examples and links to digital copies of all materials. It is recommended that students bring a laptop.