- Source: Colorado State University
- Summary:
- Groundwater pumping from the the High Plains
Aquifer has led to long segments of rivers drying up and the collapse of
large-stream fishes.
-
FULL STORY
The Arikaree River in 2000 in early summer, when water is near its maximum extent.
Credit: Kurt Fausch
Farmers in the Great Plains of
Nebraska, Colorado, Kansas and the panhandle of Texas produce about
one-sixth of the world's grain, and water for these crops comes from the
High Plains Aquifer often known as the Ogallala Aquifer the
single greatest source of groundwater in North America. A team of
researchers, including Colorado State University Professor Kurt Fausch
and Jeff Falke, a CSU alumnus and an assistant professor at the
University of Alaska Fairbanks, have discovered that more than half a
century of groundwater pumping from the aquifer has led to long segments
of rivers drying up and the collapse of large-stream fishes.
If pumping practices are not modified, scientists warn that these
habitats will continue to shrink, and the fish populations along with
them.
The research team combined modeling from the past and future to
assess changes in Great Plains streams and their fish populations
associated with groundwater pumping from the High Plains Aquifer. The
findings have implications for watersheds around the world, because
irrigation accounts for 90 percent of human water use globally, and
local and regional aquifers are drying up.
A 'train wreck'
Fausch said the study results are sobering. Based on earlier
observations and modeling by Falke and a team of graduate students and
faculty at CSU, the Arikaree River in eastern Colorado, which is fed by
the aquifer and used to flow about 70 miles, will dry up to about
one-half mile by 2045.
"You have this train wreck where we're drying up streams to feed a
growing human population of more than 7 billion people," Fausch said.
Fausch described the situation as a "wicked problem," one with no
good solution. "More water is pumped out every year than trickles back
down into the aquifer from rain and snow," he said. "We are basically
drying out the Great Plains."
Pumping has dried up streams, small rivers
Since the 1950s, pumping has extracted nearly as much water as what
exists in Lake Erie about 100 trillion gallons and almost none of
it trickles back into the aquifer.
"This pumping has dried up long segments of many streams and small
rivers in the region," Fausch said. From 1950 to 2010, a total of 350
miles of stream dried up in the large area the team studied in eastern
Colorado, southwestern Nebraska and northwestern Kansas. "Our models
project that another 180 miles of stream will dry up by 2060," Fausch
said.
The loss of fish in the area is also a concern. "What we're losing
are the fishes that require habitat found only in the rivers and large
streams of the region, and replacing them with those that can survive in
the small streams that are left," Fausch said. "We are losing whole
populations of species from rivers in that region because there's no
habitat for them."
As an example, seven of the 16 native fish species that were once
found in the Arikaree River have disappeared since the first surveys
were done in the 1940s. These fish include small minnows, suckers and
catfish, species that the CSU scientist said are not among those that
are currently federally endangered or threatened, so there's little
regulatory authority to preserve the habitats.
"We're losing fish that people really don't know about," said Fausch. "They are cool and very beautiful, but not charismatic."
Losing a river means losing more than fishes
Effects from the groundwater pumping will extend beyond the fishes
and streams, too. Farmers in that area hope to conserve enough water so
that future generations can continue to work on the land. And the
everyday places that benefit from water could also disappear.
"If they lose the river, they'll not only lose fishes, but they'll
also lose water for their cattle, and cottonwoods that provide shade,"
Fausch explained. "They also lose the grass that grows in the riparian
zone, which is critical forage for cattle in summer. Some of that's your
livelihood, but it's also the place you go for picnics, and to hunt
deer and turkeys. If you lose the river, you lose a major feature of
what that landscape is."
Fausch said that there are some signs of progress, despite the grim
findings. Local officials have put meters on wells to ensure that
farmers pump only the amount of water allowed under their permits. And
farmers are always experimenting with new technology that will allow
them to optimize the amount of water they use to achieve the highest
crop yields, since it takes electricity to pump the water from deep
underground and this is an important cost to them. This doesn't mean
that the groundwater levels that feed streams are not declining, but
instead are declining at a slower rate than in the past, he said.
Growing dryland crops an option
One additional option, though it might be a hard sell, is for farmers
to grow dryland crops, meaning that they rely only on rainfall each
year, instead of pumping water. The problem is the crop yields then vary
widely from year to year, depending on the rain.
"Every farmer understands that eventually they will no longer be able
to afford to pump as much water," said Fausch. "Farmers are amazing
economists. New options such as economical drip irrigation are being
discussed, and farmers will likely switch to these options when they
become available."
Fausch, who has studied rivers throughout his entire career, grows
wistful when talking about the research. "When we lose these rivers, we
will lose them for our lifetime, our children's lifetime, and our
grandchildren's lifetime," he said.
Even if all pumping were stopped tomorrow, the aquifer would refill
very slowly, over the next 100 years or more, said Fausch. As the
groundwater table rose, rivers would start to flow again.
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