Water Resources of the United States
Guide to USGS World Wide Web Services
You are viewing World Wide Web (WWW) pages from a U. S. Geological Survey site. Parts of the text or images may be references or "hot links" to other locations in the same document, or to other documents. These references are usually indicated by underlining the text and/or making it a different color, or displaying it in reverse video. It's important to realize that the references in USGS documents can point to documents produced and served by non-USGS sources.
USGS documents are served from 150 different sites, and reflect a variety of regional styles and interests. All of these sites can be reached from pathways starting at the USGS home page. We serve more than 7 million pages per month to more than 200,000 users. Altogether, tens of thousands of USGS WWW pages are available for your viewing.
We hope you find our pages helpful!
Browsers SupportedThe behavior of your screen depends on the particular program, or "browser," you are using to access these pages. Get assistance from your local WWW experts if you need help with your browser. Many browsers have help built into them which can be displayed by clicking on a help menu selection. This particular webserver (water.usgs.gov) recognizes your browser as one that can read HTML tables, and will present information using tables. that can not read HTML tables, and will attempt to present information in alternative formats, where possible. Other webservers may act differently.
You will be able to view nearly all the content offered on USGS pages if you have:
If a page requires more than these features to see its contents, an explanation or warning will be provided and, for critical content, an alternative meeting the above standard will be provided.
Although we recommend viewing the pages with graphics, you may set your browser to ignore graphics if your transmission speed is limited. You can access most of the content with a text-only browser, but obviously not the graphics.
Whichever browser you choose, we recommend that you get the most recent version for corrections and updates. Many problems reported to us turn out to be "bugs" in older copies of browsers. Hundreds of different browsers are used to access our pages, and it not possible for us to keep track of all browser problems.
About These Particular WWW DocumentsUSGS documents are served from about 150 sites located throughout the United States. Although the sites are managed locally, most USGS pages contain certain design elements in common. A "backbone" navigation pathway provides connectivity among all sites. Because our pages may be served from different sites, it is possible that a server that is temporarily out of commission will make some pages inaccessible or that pages will be missing some graphics. Please be patient and try again. Extended outages usually will be announced on an upper-level page.
The top of every document should have the new USGS mark, like the top of this page. (We're still in the process of converting some older pages, though.) It is not uncommon for WWW pages to reference pages on different servers and even different agencies. The USGS mark at the top of the page is your sign that you are looking at a page from USGS. Usually, clicking on the mark will bring you to the USGS home page. Besides explaining some important facts about the USGS, the home page is the head of a logical navigation path that can connect you to any public page served by the USGS.
The bottom of each page should contain a reference to a local "home page" to help you navigate the USGS network. This often is more convenient than returning all the way back to the USGS home page. Most pages also contain the the email address of the person who maintains it, and the date and time of the last modification. These are important if you are reporting a problem.
Most materials on public USGS WWW pages are in the public domain and may be freely copied, though we request the courtesy of proper citations to our work. USGS WWW pages sometimes include copyrighted materials used by permission, so you should carefully check for a copyright notice before you make a copy of any page. If you have special needs for copying or referencing our materials, or questions about how our links operate, the page maintainer will be happy to help you.
We try to do everything possible to create attractive, informative pages that work properly on your client software. If we fall short of this goal on any page, please let us know!