[Editors: The new USGS report is on the Web at
http://pubs.usgs.gov/sir/2012/5261/] TACOMA, Wash. — Geologic
barriers, the intermixing of water between aquifers through
wells, and groundwater pumping contribute to the pattern of
declines of groundwater levels of the Columbia Plateau,
according to a report published by the U.S. Geological Survey.
Groundwater from the 44,000-square-mile Columbia Plateau
Regional Aquifer, a system in decline since the 1970s, is a
critical resource for the nearly 1.3 million people in Idaho,
Oregon, and Washington, as well as providing irrigation water
for the region’s estimated $6 billion-per-year agriculture.
"This study is a beautiful example of USGS scientists doing what
we do best: making detailed measurements over a broad region,
combining those observations with historical information,
interpreting the data within a geologic context, including the
use of geologic analogues, and working well with local
partners," said USGS Director Marcia McNutt. "Understanding the
cause of