By Todd Neeley
DTN Staff Reporter
MANHATTAN, Kan. (DTN) -- Kansas officials are working to get a handle on the state of the High Plains Aquifer and questions remain about if or how long aquifer levels can be sustained.
More data is needed regarding how the aquifer behaves and how efforts by farmers and other water users could affect its future, state and university experts said during the Kansas Governor's Conference on the Future of Water in Kansas last week in Manhattan.
James Butler, senior scientist and section chief in geohydrology at the Kansas Geological Survey based at the University of Kansas, said scientists continue to unearth surprises.
Though the aquifer has continued to decline in the past two decades, Butler said a recent examination of data collected from wells raises more questions than it answers.
"Most of us realize the High Plains Aquifer is under stress," Butler said. "The aquifer in the west third of the state -- we're talking about a system under stress. What are the prospects for sustainability of the aquifer? ... We have some very valuable data sets."
In Thomas County in northwest Kansas, however, he said when researchers took time to explore data collected they found more water flowing into the aquifer than "we would have anticipated." Since the High Plains Aquifer is seasonally pumped, Butler said it was easy to compare rates for water pumping and discharge.
"We can determine pumping rate needed to maintain water balance," he said. In northwest Kansas for example, Butler said, researchers examined 182 wells, finding the total amount pumped annually averaged about 430,000 acre feet.
"If we had pumped 22% less in the area, levels wouldn't have changed," Butler said. "We think there is a significant component of water moving through the saturated zone, moving through the system. We're not completely sure. There is a larger-than-expected inflow into the system. We're unsure what's causing it."
Because factors that drive changes in water balance will change, he said researchers will need to continue to study how the aquifer recharges.
Researchers have been collecting well data for years, Butler said, but only recently started to look more closely at what it might be saying about a so-called water balance -- withdrawals versus recharge.
"Collecting data sets takes a lot of effort," he said. "We haven't spent much time actually studying data. Too often we're leaving a lot of information in the files because we don't have time to explore it."
A Kansas State University study released this month found Kansas reached peak groundwater depletion -- or depletion caused by over-tapping an aquifer beyond the rate of available recharge -- in the High Plains Aquifer in 2010.
The study concluded, "The groundwater resources of the High Plains Aquifer are vulnerable, and society has the opportunity now to better understand the tapping processes and to plan for a more resilient future."
KANSAS AG EFFORTS
Farmers can take steps to make the aquifer more sustainable, according to work being done in one local enhanced management area, or LEMA, in Sheridan County in northwest Kansas, said Bill Golden, research assistant professor in the department of agriculture economics at Kansas State.
Water users in the Sheridan County LEMA voluntarily follow an annual 55-inch water pumping allocation per acre aimed at reducing overall pumping in the LEMA by 20%. It is a five-year program and producers in the LEMA can vote to end involvement on an individual basis.
"We know today the aquifer is over-appropriated," Golden said.
Much has been made about how producers who reduce water used to grow crops are likely to suffer lower yields and generate less crop income.
However, Golden said a recent study he conducted in Sheridan County where producers voluntarily provided data on cash flow, water usage and other information, found farmers on voluntary water allocations are competitive with their counterparts not in LEMAs.
Economic models generally show farmers experience lost revenues as they reduce water usage, Golden said. In the Sheridan County LEMA, however, he said he has seen producers adapt to water allocations.
For instance, there was a spike in acres planted to sorghum in 2013 in response to a higher price and the 2012 drought. Sorghum is a more water-efficient crop compared to corn.
"The majority of farmers in Sheridan County were down to deficit irrigation," Golden said.
In 2013 LEMA farmers reduced total irrigated corn acres by about 20% and increased sorghum acres. "We thought farmers would expand dryland acres and keep irrigating corn," he said.
What's more, an ongoing five-year study among farmers in the LEMA found net cash flow was higher per inch of irrigation compared to producers out of the LEMA in surrounding areas. In Golden's study net cash flow is defined as revenue minus variable expenses and land rent.
That was the case, although farmers in the LEMA on average produced 198-bushels-per-acre corn compared to 212-bpa corn outside the LEMA in 2013. Golden cautioned the producer sample is not considered to be statistically valid and more data is needed to reach broader conclusions.
Though more data is needed, Golden said net cash flow on corn in the LEMA was about $403 per acre compared to $397 net cash flow on corn outside the LEMA. "So producers inside the LEMA made as much money on corn as those outside the LEMA," he said.
Following the 2012 drought, Golden said farmers in the LEMA cut water use in 2013 by about 25%. When it comes to irrigated sorghum acres, he said LEMA farmers cut irrigation by more than 400% from 2012 to 2013 in Sheridan County. Farmers outside the LEMA maintained irrigation levels on sorghum.
The groundwater study -- Steward, D.R., Allen, A.J., Peak groundwater depletion in the High Plains Aquifer, projections from 1930 to 2110. Agric. Water Manage. (2015) -- can be viewed here:
Todd Neeley can be reached at email@example.com
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