Description
Physical Description:ix, 76 pages : illustrations, maps ; 28 cm.
Format:System requirements: Adobe Acrobat Reader.
Mode of access: Internet from the USGS Web site. Address as of 1-14-02: http://water.usgs.gov/pubs/wri/wri014081/wrir01-4081.pdf; current access is available via PURL.
Bibliography:Includes bibliographical references (pages 62-64).