The U.S. Geological Survey (USGS) recently released a new report entitled “Ground-Water Availability in the United States.â€Â The article is written for a broad range of audiences which makes an interesting read for anyone interested in what scientists know (and don’t know) about the nation’s groundwater supply. In addition, comprehensive maps and diagrams illustrate the varying features of aquifers around the county.Â
Several facts and estimates cited in the report truly put into perspective how crucial the groundwater supply is to the country. One recent study estimated the average pumpage of groundwater in the U.S. in 2000 to be 83 billion gallons per day. However, compare this figure with the study’s estimate that 1 trillion gallons per day are naturally recharged to the groundwater supply and one might wonder how some aquifers continue to decline. Part of the answer is some aquifers have much higher recharge capabilities. As the report explains, the vast majority of aquifers in the arid west are recharged at less than inch per year while most of the eastern U.S. recharges at more than 10 inches per year.Â
While broad in scope, the report offers a very comparative glimpse into the unique characteristics of aquifers throughout the country. Just 20 “principal aquifers†account for about 90 percent of the ground water withdrawals in the nation. Of these 20 aquifers, seven are located primarily in portions of Oregon, Washington, California, Nevada, Idaho, and Arizona. Not surprisingly, many of these aquifers are suffering from declining water tables.    Â
To learn more, follow the link from the following webpage to download and view the document:
http://pubs.usgs.gov/circ/1323/.
