OPEN-FILE REPORT 2004-1014 Geophysical, Sedimentological, and Photographic Data from the John Day Reservoir, Washington and Oregon: Data Archive and Preliminary Discussion by VeeAnn A. Cross and David C. Twichell INTRODUCTION: The John Day Reservoir, also known as Lake Umatilla, occupies a 123 km long section of the Columbia River, and was formed after completion of the John Day Dam in 1968. Recently, concerns about declining stocks of endangered anadromous salmonids in the Columbia River basin raised the issue of restoration of riverine functions in this and other Columbia and Snake River reservoirs. One option for restoration of riverine functions includes lowering water levels within selected reservoirs such as the John Day Reservoir. Questions about how much sediment has been trapped by this dam warranted a detailed study of the floor of the reservoir to assess changes that had occurred since impoundment. High-resolution geophysical mapping techniques were employed to provide, to our knowledge, the first detailed view of the floor of the reservoir since its formation. This geophysical "road map" in concert with bottom video images, some sediment samples, and historical data collected prior to creation of the reservoir were incorporated into a GIS. The subsequent text summarizes the techniques used in this study. It also provides a preliminary analysis of the results and a background for the GIS that accompanies this report. DIRECTORY STRUCTURE: Top level directory: index.htm - This file is intended to be the starting point for the DVD-ROM access. It is written in the Hypertext Markup Language utilized by the World Wide Web (WWW) project and must be opened with a WWW browser. Once opened, the user may browse the DVD-ROM's contents as they would browse pages from the WWW. readme.txt - ASCII text file containing a description of this DVD-ROM. This file may be viewed or printed with any system program capable of opening ASCII text files. johnday.apr - ArcView project file created with ArcView 3.2a on a Windows2000 computer. Directories: Directory data - What follows is a brief description of the data contained in the underlying directories. For a more complete description of the data, refer to the data section of this DVD, or the metadata associated with each data file. This directory contains the following subdirectories: basemap - contains shoreline data from the John Day Reservoir, as well as the locations of the McNary and John Day dams which enclose the reservoir. These data are available as ESRI shapefiles. Also available in this directory is a mosaic of pre-impoundment aerial photographs of the John Day Reservoir interpretation - ESRI shapefiles of interpreted layers of the reservoir floor. nav - contains navigation data, both as ASCII text files and as ESRI shapefile, pertaining to sidescan and seismic data collection in the John Day Reservoir. samples - ESRI shapefiles indicating locations of lake bottom video and lake bottom still photos and/or sediment samples. The subdirectories contain bottom images, with the directory name being an indicator of the year the images were collected. Either 2000 (in img2000) or 2002 (in img2002). segy - CHIRP seismic-reflection profiles in SEG-Y format. seisimages - contains JPEG images of all the seismic- reflection profiles collected as part of this study. sidescan - contains sidescan-sonar mosaics of the reservoir floor. The subdirectories indicate the projection of the imagery, either geographic or stateplane (Washington Stateplane South). These images are available in TIFF and MrSid image formats. Directory htmldocs: contains the HTML pages accessed within this Open-File Report. This directory contains the subdirectory icons which contains all the image files and icons utilized in constructing the Open-File Report HTML pages. Directory metadata: contains the HTML and ASCII text versions of the metadata files for all the data contained in this Open-File Report. This metadata is organized into the following subdirectories: basemap, interpretation, nav, samples, segy, seisimages, sidescan. DISCLAIMER: This DVD-ROM publication was prepared by an agency of the United States Government. 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