Irrigation is mining a finite resource

Nebraska isn't thought of as a mining state, but we need to change our thinking.

Yes, we have oil and gas, which remove finite amounts of a valuable resource from the ground, and most people don't think of sand and gravel operations as "mining," but they are. And, quarries aren't unknown.

But there's a much more extensive "mining" operation going on in the Cornhusker state, and it can't continue at its current rate.

The Ogallala aquifer covers 174,000 square miles under eight states, including most of Nebraska. It ranges from a few feet deep to more than 525, formed when the rubble from the emergence of the Rocky Mountains poured into the remains of ancient valleys and channels.

Looking at cold, clear fresh water produced from deep wells, it's hard to believe that much of it dates back to the last ice age.

As huge as that water supply is, and while it is somewhat recharged by rainfall, it has its limits.

That's especially true now, while we're in the midst of a seven-year drought.

Starting 50 years ago, we began developing large-scale irrigation to the point that today, we're pumping water out of it four times faster than it can be replenished.

That mining has resulted in groundwater declines of 30 to 50 feet over the years -- not news to readers in far Southwest Nebraska, but alarming to geoscientists such as Mark Burbach at the University of Nebraska-Lincoln.

"We certainly aren't coming to the bottom of the well, so to speak, but the level of groundwater declines in many parts of Nebraska are indisputable, and could even be viewed as alarming," Burbach said.

Dundy County is among the areas with the steepest declines, 30 feet or more over the past six years. Counties showing drops of 15 feet or more include Chase and Perkins counties.

The only places showing a rise in groundwater level were areas which received large amounts of rain just before readings were taken from monitoring wells, or such as a couple of spots along the North Platte River which rely heavily on surface irrigation.

Ground and surface water irrigation and their relationship are key to the Republican River conflict with Kansas, and the groundwater declines are a sharp illustration of the cause of the problem.

It's also a reminder of the just how important it is to find ways to efficiently and fairly distribute a finite, but vital, natural resource.