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Title
A Sediment Quality Assessment and Management Framework for Dam Removal Projects
Alternative Title
Managing Watersheds for Human and Natural Impacts: Engineering, Ecological, and Economic Challenges, EWRI and ASCE 2005 Watershed Management Conference, Williamsburg, Virginia, July 19-22, 2005
Creator
Brian Graber
Jim Turek
Joe Rathbun
Karen Pelto
Laura Wildman
Massachusetts Department of Fish & Game
Michigan Department of Environmental Quality
NOAA Restoration Center
American Rivers
Date Created and/or Issued
2005
Contributing Institution
UC Riverside, Library, Water Resources Collections and Archives
Collection
Clearinghouse for Dam Removal Information (CDRI)
Rights Information
Copyrighted
Transmission or reproduction of materials protected by copyright beyond that allowed by fair use requires the written permission of the copyright owners. Works not in the public domain cannot be commercially exploited without permission of the copyright owner. Responsibility for any use rests exclusively with the user.
Description
Scope/Content: Abstract: Sediment trapped behind a dam may be chemically contaminated, with the potential to cause toxicity and contaminant bioaccumulation in biota and also to greatly complicate dam removal. However, sediment quality has been assessed in only a small fraction of the more than 80,000 reservoirs in the U.S. Therefore, efficient screening and assessment techniques are essential to determine the level of sediment management necessary for dam removals and to avoid unnecessary impacts to the river system. The Massachusetts Riverways Program is working with the USGS to develop the Regional Impounded Sediment Quality Assessment (RISQA), a GIS-based model that provides an initial screening of the probability of contamination in impoundment sediment. The model combines land-level data, such as historic land use and known contamination sites, with the drainage network in the watershed upstream of an impoundment. Reservoirs identified by the RISQA model as likely to contain contaminated sediments should be individually assessed using a sampling design appropriate for the local situation, a set of sediment quality criteria against which to judge the magnitude of the problem, and a decision framework for selecting the appropriate management action. Survey design and sampling techniques are well established, and range from a quick, qualitative reconnaissance survey to a statistically-rigorous coring survey. Sediment quality criteria vary from state to state, and are typically either narrative standards or are based on biological/toxicological assessments and/or bulk sediment chemistry. In addition to sediment quality criteria assessments, the proposed sediment management decision framework considers sediment transport capacity of the stream, downstream sensitivity to sedimentation, and contaminant bioavailability. Available management options include natural erosion and deposition downstream, staged dam removal, full or partial dredging, isolation/stabilization, or a combination. Choosing among the management options requires consideration of site-specific social concerns and financial limitations as well as technical issues. This paper outlines a process for sediment assessment as well as a potential management framework when dealing with sediments on a dam removal project.
Type
text
Form/Genre
digital copy
Identifier
ark:/86086/n2np2422
121
Subject
Sediment and channel dynamics
Dams
Dam retirement
Place
US

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