"811 is the new number you should call before you begin any digging project. A new, federally-mandated national 'Call Before You Dig' number, 811 was created to help protect you from unintentionally hitting underground utility lines while working on digging projects." The site describes how 811 works and when to call (tree, pond, mailbox, fence, concrete), and links to state specific contacts. Also includes tips and testimonials and public service announcements. Note: may not display properly in all browsers.