The USGS Web site Water Resources of the United States can direct you to information about your local water body. Under the heading "Local Information" click on "Local Websites & USGS Contacts in Your State!" There you can select your state on a map to find local information.
Below "Local Information" on this site is a link to "Connections." If you click on the link "Search USGS Websites" and type a name (such as "Mississippi") in the Search field and then click "seek", a list of search results is shown.