Aquifer Recharge projects catching on in water-strapped cities
The Ogallala Aquifer occupies the High Plains of the United States, extending
northward from western Texas to South Dakota and is the major aquifer for Howard &
Martin Counties. The Ogallala was created 10 million years ago by fluvial deposition
from streams that flowed eastward from the Rocky Mountains during the Pliocene
epoch. Erosion has removed the deposits between the mountains and the existing
western boundary of the Ogallala, so there is no longer water recharge being received
from the Rockies.
Natural recharge to the Ogallala aquifer occurs primarily from rain, snowmelt, river
and reservoir leakage, or from irrigation. It is recognized that playa lakes are the
primary points of most natural recharge. Recent studies have estimated an average
recharge rate for the entire High Plains region of approximately 0.5 of an inch per year.
The amount of water in storage in an aquifer is reflected in the elevation of its water
table. If the rate of recharge is less than the natural discharge rate, the water table will
decline and the aquifer's storage will decrease.
The use of artificial recharge to store surplus surface water underground can be
expected to increase as growing populations demand more water. Artificial Storage and
Recovery (ASR) programs are being implemented as a way to store water in aquifers
during times when water is available and recover the water when it is needed. The State
of Texas has seen ASR programs implemented in such places as the San Antonio Water
System (SAWS). The Corpus Christi Aquifer Storage and Recovery Conservation
District is in the preliminary testing stage for the ASR program.
As the artificial aquifer recharge gains momentum state wide it is also becoming of
interest nationally. Utilities and water managers from Florida to California are
beginning to rely on recharged aquifers to help maintain water supplies during periods
of drought. For instance, Florida aquifers are routinely recharged in the winter, and
then tapped in the summer when water demand exceeds supply. In other areas,
geologic constraints and the need for long-term storage have led water managers to view
aquifer recharges and withdrawals as a last resort.
In Albuquerque, water officials hope the Bear Canyon pilot project will demonstrate
that infiltrated water from the Rio Grande can recharge the over pumped Middle Rio
Grande Basin aquifer and effectively store water for use in times of drought. Stephanie
Moore, manager of the project, noted that cities typically store water in reservoirs, but in
dry states like New Mexico, 10 to 15 percent of that water is lost to evaporation. Storing
some of the water underground reduces that loss to about 3 percent, and shields it from
the vagaries of the elements.
Researchers continue to work on methods to increase natural recharge to the aquifer
and to improve water-use efficiency. The prospects for the future of the Ogallala aquifer
ultimately depend upon its management by each of its water users.
The Permian Basin Underground Water Conservation District invites you to view their
website at www.pbuwcd.com for more information on Recharge Enhancement. You can
also call their office at 432-756-2136 or email us at permianbasin@sbcglobal.net.