The atlas, which covers groundwater resources in Alaska as well as Hawaii, Puerto Rico, and the U.S. Virgin Islands, was presented at the Alaska Water Well Association meeting in Anchorage on February 13.
Alaska's groundwater is generally of good quality and is suitable for most uses, although hard water and naturally high iron concentrations are common. There are localized water quality problems with various natural and man-made causes. These include natural geologic conditions, such as aquifers in marine sedimentary rocks, that can produce brackish water. Natural biologic processes and contamination from septic tank discharges can cause high nitrate concentrations, and intensive pumping in aquifers near the coasts can mix sea water with freshwater, making it unfit for most uses.
Most of the groundwater pumped in Alaska comes from sand and gravel aquifers that are typical of a relatively small part of the state. The consolidated bedrock that covers more than 70 percent of Alaska forms aquifers with great variability, and much remains to be learned about the groundwater that might potentially be tapped.
Information on current and historical groundwater conditions in Alaska, as well as the chemical quality of water pumped from aquifers around the state, are described in the atlas.
Although about 23 percent of the freshwater used in Alaska comes from groundwater sources, 90 percent of the state's rural population depends on groundwater for domestic use.
Most of Alaska's groundwater is pumped from only a few unconsolidated- deposit aquifers formed by glacial outwash and river sands and gravel, which are easily developed and generally yield good quality water.
Juneau, Fairbanks, and about fifty smaller communities depend primarily on groundwater for public supplies.
Anchorage was a heavy user of groundwater through 1985, causing water levels to decline up to fifty feet. Construction of a pipeline from Eklutna Lake dramatically reduced reliance on groundwater.
Fairbanks' population relies equally on groundwater from both the unconsolidated sand and gravel deposits of the Tanana River Basin aquifer and on fractured-rock aquifers.
Permafrost presents unusual groundwater development and withdrawal problems that are explained in some detail in the atlas. Continuous permafrost, which yields little groundwater, covers the northern part of the state.
The USGS atlas summarizes groundwater information for Alaska, Hawaii, Puerto Rico and the U.S. Virgin Islands, and provides a list of published reports on groundwater in each area.
Printed in an 18-by-24 inch format with numerous maps and illustrations, this atlas joins twelve others in a series that together provide a source of comprehensive information, written in nontechnical language, on the groundwater resources of the nation.
The atlas, entitled "Ground-Water Atlas of the United States, Segment 13, Alaska, Hawaii, Puerto Rico and the U.S. Virgin Islands," by James A. Miller, R.L. Whitehead, and Perry G. Olcott, is published as USGS Hydrologic Investigations Atlas 730-N.
Copies may be purchased for $4.00 each from the Information Services Branch, USGS, Box 25286, Denver, CO 80225, telephone 1-800/435-7627 or by fax at 303/ 202-4693. There is a $3.50 shipping and handling charge for each order mailed. An abstract and ordering information is available on the Internet at: <http://wwwcapp.er.usgs.gov/publicdocs/gwa/>
Copies will be also available at the Anchorage Earth Science Information Center, 4230 University Drive, Anchorage, AK. phone 1-800/USA-MAPS.
As the nation's largest water, earth and biological science and civilian mapping agency, the USGS works in cooperation with more than 2000 organizations across the country to provide reliable, impartial, scientific information to the public, resource managers, planners, and other customers. This information is gathered in every state by USGS scientists to minimize the loss of life and property from natural disasters, contribute to sound conservation, economic and physical development of the nation's natural resources, and to enhance the quality of life by monitoring water, biological, energy, and mineral resources.-
For additional information on local groundwater availability and quality in Alaska, please contact Gordon Nelson. Telephone: 907/786-7111, Fax: 907/786-7150) Web site: <http://www-water-ak.usgs.gov>
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