Ogallala Aquifers Drying Less Water for Irrigation

Plans 45 Years of Well Data Show Near 100-foot Declines in Some Texas Countries

The Ogallala Aquifer across the region has dropped about 325 billion gallons every year for at least the past four decades.

To put that number into perspective, the roughly 1-foot annual drop in the aquifer is more than enough to supply all of Lubbock's municipal water needs for 25 years.

And it has dropped about that amount every year since 1969, according to High Plains Underground Water District data analyzed by the Lubbock Avalanche-Journal, which is owned by Morris Communications, the parent company for The Topeka Capital-Journal.

In all, across the district's 16 counties, the aquifer has fallen about 40 feet, a decline of roughly 44.9 million acre-feet since 1969.

Primarily used for irrigation, the aquifer is critical to the region where agriculture represents about 30 percent of the economy. Agriculture's direct economic impact for the High Plains is upward of $3 billion annually.

As vast as the High Plains aquifer is — it spans eight states and holds nearly 3 billion acre-feet of water — it could still run dry. A Kansas study last year estimated it could in less than 50 years.

It likely will be sooner here.

Rapidly declining

That nearly 45 million-acre-foot decline in the Ogallala Aquifer equates to about 14.6 trillion gallons of water over 45 years.

That is enough — if the average American uses, conservatively, about 69 gallons a day — to meet the Lone Star State's entire municipal water needs for roughly 20 years.

An acre-foot of water is used to describe large water resources such as river flows and reservoirs. It is the equivalent of 1 acre of surface area covered by water 1 foot deep — 325,853 gallons.

The aquifer decline is larger than Lake Mead, which filled to capacity is roughly 28.9 million acre-feet. Lake Mead is the man-made reservoir in Nevada that supplies Las Vegas.

The reason for the ambiguity is complicated. Part of the answer is in what is actually being measured — how much is in irrigation wells. The High Plains district isn't yet measuring how much water is taken out of the Ogallala.

This distinction is important because of the second reason for the uncertainty. The Ogallala Aquifer moves — albeit slowly — about a foot a day from west to east, according to the U.S. Geological Survey.

‘Not sustainable'

The Ogallala Aquifer is among the largest aquifers.

It extends 174,000 square miles beneath portions of eight states from South Dakota to Texas in one of the most productive agricultural regions in the world. Growing concern over extensive irrigation has led to, among other things, a state-mandated regional approach to conservation that requires planners to craft strategies that include a desired future condition.

The goal for Lubbock and the region is 50 percent left in 50 years.

‘Important resource'

The region was built on agriculture. Irrigation made it more profitable.

Economic researchers at the institute estimate a third of the ag revenue would be lost with a return to dryland farming, which typically has lower yields.

Less than 30 percent of the cropland overlying the aquifer is irrigated. But more than half of the counties where depletion is a threat to irrigated agriculture are in Texas, according to a 2012 Texas Tech report on the future of the Great Plains.

And of those 19 Texas counties, nine are within the High Plains Underground Water District.

LifeExpectancyOfTheOgallala: SeeVideo

Source: CJOnline

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Taxonomy

• Agriculture
• Irrigation
• Aquifer Recharge