Aquifer: Aquafornia debuts its new Weekend Wrap-up feature called “Water Word of the Week” with a word that coincidentally begins with the first letter of the alphabet.

A search on Water Education Foundation’s new site Aquapedia, a free online water encyclopedia, defines aquifers as “an unseen but critical resource in California’s water supply system. These natural basins that sit below the surface are found underneath 40 percent of California’s land area.” Along with the definition are diagrams and sections titled Aquifer Overview and Aquifer Challenges. (photo: Great Basin National Park has a regional aquifer system.)

Another online source of general reference information is “Aquifer Basics” from the U.S. Geological Survey (USGS). The website also includes a listing of principal aquifers such as the California Central Valley aquifer system and Coastal Basin aquifers.

Making headlines recently due to drought in the Southwest has been the Ogallala Aquifer, which encompasses 174,000 square miles underneath parts of eight states (South Dakota, Nebraska, Wyoming, Colorado, Kansas, Oklahoma, New Mexico and Texas). Author Marc Reisner wrote about it in “Cadillac Desert: The American West and Its Disappearing Water,” published in 1986. In July 2013, NBC Learn produced a YouTube video featuring an overview, background and a wide-range of interviews about the Ogallala Aquifer.

For a better understanding of aquifers, read Western Water (May/Jun 2011) titled “Preserving Quantity and Quality: Groundwater Management in California.” “In California’s basins, groundwater occurs in aquifer systems composed of clay, silt, sand and gravel,” Gary Pitzer wrote. “The sand and gravel provide water to wells.”

Also, a USGS study published in May 2013 addresses the nation’s aquifers.