Generous rain in recent weeks took southeastern Nebraska out of the drought zone. But the moisture really isn’t enough to assuage worries about global warming and permanent climate change.
And the dramatic declines in groundwater levels in Nebraska reported this week underlined the long-term problem that the state faces.
Since the current drought began in 2000, groundwater levels in parts of the state have dropped by more than 30 feet, reported Mark Burbach of the University of Nebraska’s School of Natural Resources.
This is an ominous trend for counties that depend heavily on irrigation, including those along the Platte River and Perkins, Chase and Dundy counties in southwestern Nebraska.
Agriculture in the state has become increasingly dependent on the water supplies in the Ogallala Aquifer, that immense underground reservoir of water that accumulated over centuries.
Large-scale irrigation began in Nebraska in the 1950s. As wet and dry cycles alternated since then, water tables in parts of Nebraska have fallen, only to recover somewhat in wet cycles.
But the long term trend is still in the wrong direction.
“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.
In southwest Nebraska and Box Butte County, groundwater levels have dropped more than 50 feet since large scale groundwater irrigation began.
Southeastern Nebraska may have become more sanguine as rain pelted down recently. But even though there were flood warnings for some of the state’s rivers, the overall picture didn’t improve much.
Actually, the state as a whole was in better shape a year ago. According to the National Drought Mitigation Center, about 9 percent of Nebraska was out of the drought zone last week. A year ago, the figure was about 13 percent. And this year, more than 30 percent of the state was experiencing extreme drought. A year ago, none of the state was.
Water policy in Nebraska is now based in theory on the premise that water usage should be sustainable.
Unfortunately, no one really knows what it will take to sustain groundwater levels.
It will be difficult enough to bring groundwater usage down to a level that will be sustainable based on historic rainfall totals.
But with every year that the drought continues, there is more doubt that historic rainfall totals are a reliable guide to the future.