Although there are various methods for restricting access to documents stored on a World Wide Web (WWW) site1 (a Web site), none of the widely used methods is completely suitable for restricting access to Web applications hosted on an The U.S. Geological Survey (USGS) is committed to providing the Nation with reliable scientific information that helps to enhance and protect the overall quality of life and that facilitates effective management of water, biological, energy, and mineral resources (http: //www.usgs. gov/). Information on the Nation's water resources is critical to ensuring...