Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock () or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Map showing gravity-based groundwater-storage and water-level change in a portion of the Tucson AMA, from spring 2008 to summer 2011.
Public Domain.
