Water for Food

What happens in Neb., stays in Neb… and other things you didn’t know about the Ogallala Aquifer

April 29, 2014

Credit: U.S. Geological Survey

Credit: U.S. Geological Survey

For one thing, the aquifer that most think of — one of the world’s largest that underlies parts of eight U.S. states — is technically not the Ogallala Aquifer, but the High Plains Aquifer.

“That’s been a source of confusion,” said hydrogeologist Jim Goeke, professor emeritus at the University of Nebraska-Lincoln. “We use the names interchangeably, but they’re not the same. We have other productive aquifers in Nebraska in hydraulic connection that encompass the entire High Plains Aquifer.”

But the name aside, what bothers Goeke more is the common misinformation he encounters about aquifers, especially the High Plains.

“People think it’s an underground lake, that if you pump water out of Nebraska, it will affect water levels in Texas. That’s absolutely not true,” he said.

It’s easy to understand the confusion when the aquifer is often referred to in such terms as a vast underground sea and is illustrated with graphics depicting, well, an underground lake.

But, in fact, aquifers are layers of water-bearing porous rock or sand that allow water to move between layers of nonporous rock. Water filters through cracks and other spaces in the soil and rock until it reaches an impermeable layer. The water can be extracted using wells.

That geological complexity has important implications. In the High Plains’ case, the Republican River, which flows across Nebraska’s southern end, cuts the state’s section of the aquifer off from Kansas and points south.

“It’s one aquifer, but it’s not hydraulically connected,” Goeke said, adding that he runs into decision-makers and even engineers who don’t understand that “what happens in Nebraska, stays in Nebraska.”

That Nebraska’s and Texas’ groundwater fates aren’t linked stems from other geological quirks. Nebraska, for example, is privileged with significantly higher recharge rates thanks to the Sandhills, which spans the state’s western half. Its sandy soils and wetlands are particularly effective at filtering water quickly. About two-thirds of the High Plains’ water is stored in Nebraska.

That recharge rate is one reason why Nebraska’s aquifer drawdowns differ so dramatically from other regions. Texas, for example, has depleted 29 percent of its portion of the High Plains, compared to Nebraska’s 0.5 percent, according to the U.S. Geological Survey. Other factors include Texas’ 30-year head start on intensive irrigation and Nebraska’s groundwater management efforts as irrigation ramped up, which has helped protect the resource.

While Texas and Kansas are facing significant groundwater problems, it doesn’t mean Nebraska’s 0.5 percent drawdown hasn’t wrecked havoc on the state’s natural resources, said Goeke, citing another common misconception.

“That half-percent has affected stream flows, primarily in the Republican Basin,” he said. “We have a legal obligation to deliver water to Kansas, and as we pump groundwater in Nebraska, we have affected the tributary flows to the Republican.” Similar problems exist with the Platte River, which affect endangered species.

James Goeke holds sediment material at a High Plains Aquifer drill site in western Neb. Credit: University of Nebraska-Lincoln

Jim Goeke holds sediment material at a High Plains Aquifer drill site in western Neb. Credit: University of Nebraska-Lincoln

The Nebraska legislature recently created a Water Sustainability Fund to better coordinate surface and groundwater management and to provide much needed resources to address water scarcity and quality throughout the state. Texas, too, has begun to take steps to slow drawdowns, particularly as an extreme drought further threatens water resources.

Goeke’s advice for High Plains Aquifer users: Make every drop count.

Some irrigators aggressively manage their water use, adopting more efficient methods, because they realize using less water helps their bottom line, but many of their neighbors haven’t gotten that message yet, he said. “We have momentum in the history of water use, and it’s very difficult to turn it around.”

But there’s reason for optimism, he added. “We’ve got a lot of innovative techniques that we’re developing, plus this new sustainability legislation. In Nebraska, we’ve been doing good things, aggressive things, to promote sustainability of the water resources.”

 
Jim Goeke retired in 2011 after 41 years as a research hydrogeologist with the Conservation and Survey Division at the University of Nebraska-Lincoln. He was stationed at the West-Central Research and Extension Center in North Platte, Neb.


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