US Geological Survey
U.s. Geological Survey: Where Is Earth's Water Located?
Find out how much of the water on Earth is actually usable by humans, and where the rest of it is located. Learn where our water comes from and why it never runs out. Click Home to access the site in Spanish.
US Geological Survey
Usgs: How Much Water Is There on (And In) the Earth?
The USGS gives an overview of the amount of water on Earth and where it is located. It gives a few interesting facts about the Earth's supply of water. Click Home to access the site in Spanish.
US Geological Survey
Earth's Water: Rivers and Streams
The USGS explains the definition of a river and how a river is supplied with water. Included is a cross section of a river. Click Home to access the site in Spanish.
US Geological Survey
Usgs: Trends in Ground Water Use, 1950 2005
This site from USGS describes the importance of ground-water, provides a map of ground-water use (by state), a map of the percent of total withdrawals coming from ground water, and a map of the percent of public-supplied population...