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Environmental Assessment
Development and Implementation of a Protocol
for High-flow Experimental Releases from
Glen Canyon Dam, Arizona, 2011 - 2020

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The Department of the Interior, acting through the Bureau of Reclamation, is proposing to develop and implement a protocol for high-flow experimental releases from Glen Canyon Dam to better determine whether and how sand conservation can be improved in the Colorado River corridor downstream of Glen Canyon Dam including areas within Grand Canyon National Park. Under the concept of high-flow experimental releases, sand stored in the river channel is suspended by high-volume dam releases and a portion of the sand is redeposited in downstream reaches as sandbars and beaches, while another portion is transported downstream by river flows. These sand features and associated backwater habitats provide key wildlife habitat, protect archaeological sites, enhance riparian vegetation, and provide camping opportunities along the Colorado River in Grand Canyon National Park.

This protocol for high-flow experimental releases from Glen Canyon Dam is part of the ongoing implementation of the Glen Canyon Dam Adaptive Management Program. As part of the GCDAMP, the protocol is a component of Interior’s compliance with the Grand Canyon Protection Act of 1992 (Public Law 102-575).

 Cover pages
140 KB
 Table of Contents
122 KB
 Executive Summary
116 KB
 Chapter 1 - Introduction
310 KB
 Chapter 2 - Description of Alternatives
255 KB
 Chapter 3 - Affected Environment and Environmental Consequences
1.1 MB
 Chapter 4 - Consultation and Coordination
120 KB
 Chapter 5 - References
196 KB
 Appendix A - Federal Register Notice (December 31, 2009)
48 KB
 Appendix B - Science Plan
212 KB
 Appendix C - Biological Assessment and Supplement
687 KB
 Appendix D - Hydrology Input to Sediment Model
 123 KB
 Appendix E - Sediment Budget Modeling Methods using CRSS Hydrology Output
958 KB 
 Appendix F - Methods for Estimating the Impacts of HFEs on Hydropower at GC Dam
147 KB 
 Appendix G - Letter of Concurrence from AZ State Historic Preservation Office
240 KB
 Appendix H - Biological Opinion
1.3 MB 
 Entire Document
 5.2 MB
 FINAL Finding of No Significant Impact
 2.5 MB



Last updated: May 23, 2012