The Future of the Ogallala Aquifer

The Ogallala aquifer irrigates some of the most important cropland for food and fuel. For years, it's been steadily depleting leaving some to wonder about the sustainability of tapping into it for increased corn irrigation and ethanol production.
By Anduin Kirkbride McElroy | January 01, 2008
A summer's flight from Chicago to Denver can give one a new perspective on water use. Before the plane climbs above the clouds, one can see vast stretches of prairie land, cut into rectangles of dark green crops. From the sky, the crops seem to go on and on, delineated only by roads, trees and winding rivers. According to the National Corn Growers Association, more than 85 percent of all corn produced in the United States is nonirrigated, and much of it is raised on this fertile land that's been under agricultural production since white men settled the region in the 1800s.

As the flight continues over Illinois, Iowa, Nebraska and eastern Colorado, one might notice that the farmscape begins to change. Circles, one-half mile in diameter, start to be dispersed amongst the rectangles. Further on, the land looks like a pale green and yellow checkerboard with dark green checkers placed atop of the squares. As the plane descends over eastern Colorado, the prevailing color of the land is brownish yellow, a striking contrast to the circles full of dark green crops.

The land west of the Missouri River is fertile, but crops must be coaxed out of the ground with irrigation. The dark green circles are a result of center-pivot irrigation, which enables the arid prairie states to be as fruitful as the Midwestern states. Colorado, for example, with its mountains and high prairies, is the 13th largest corn-producing state in the United States, according to Dave Kramer, general manager of Sterling Ethanol LLC and Yuma Ethanol LLC in northeastern Colorado. What's more, Yuma County is one of the top three largest corn-producing counties in the country, producing 42 million bushels per year.

Irrigation has also enabled Nebraska to be an integral part of the Corn Belt. About 60 percent of corn acres in the state are irrigated, according to the Nebraska Corn Board. The state's corn supply and ambitious development recently bumped its ranking to the second largest ethanol-producing state, after Iowa. Nebraska has more than 1,565,000 gallons of annual capacity built or under construction.

Water Source
Yes, the land is fertile, thanks to a generous supply of groundwater. The High Plains aquifer, also known as the Ogallala aquifer, lies under portions of eight states: South Dakota, Nebraska, Wyoming, Colorado, Kansas, Oklahoma, New Mexico and Texas. It is one of the largest aquifers in the world, spanning about 175,000 square miles. According to the U.S. Geological Survey, approximately 27 percent of the irrigated land in the United States is in this region, and about 30 percent of the groundwater used for irrigation in the United States is pumped from the Ogallala aquifer. In 2000, irrigation withdrawals were 17 billion gallons per day and 1.9 million people were supplied by groundwater from the Ogallala aquifer with total public supply withdrawals of 315 million gallons per day, according to the USGS. The aquifer is not only large, but it's also accessible. "It's relatively shallow, the quality is relatively good, so it's very user friendly," says David Hume, a hydrogeologist and senior associate at Leggette, Brashears & Graham Inc.

The aquifer was formed over millions of years, but has since been cut off from its original natural sources and is being depleted faster than it can be recharged. The water table in the Ogallala Formation is separated from overlying land-use practices by as much as 400 feet of unsaturated sediments, and recharge has been estimated to take at least 50 years. Over extraction has led to substantial declines in the water table in many places, complete exhaustion of extractable groundwater in others, and debate and legislation about the aquifer's future, according to a report by Environmental Defense, a nonprofit environmental advocacy group formerly known as the Environmental Defense Fund. The report, "Potential Impact of Biofuels Expansion on Natural Resources; a case study of the Ogallala aquifer region," was released in September. Large portions of the aquifer show declines in the water table of more than 100 feet. Some reports have found that the water level is dropping by 3 to 5 feet a year in some areas. Estimates for its lifespan range from 60 to 250 years, depending on the area.

In the arid Plains, states have developed complicated legal arrangements for issuing water rights and developing water diversions. Water is appropriated by the government and the rights to it are traded and sold to the highest bidder. Lately, expanding cities have bought water rights from irrigation districts—essentially putting irrigated agriculture out of business. "Some areas in the Ogallala aquifer region, particularly in parts of Colorado and Nebraska, have existing groundwater protections that will reduce opportunities to convert new land to irrigated production," the Environmental Defense report states. "Strengthening and expanding any existing local and regional groundwater conservation efforts may be one of the most effective ways to minimize groundwater depletion and the destruction of significant remaining blocks of wildlife habitat."

Indeed, water rights are a significant issue in Colorado, as current producer Front Range Energy LLC found out when developing its plant in Windsor. According to BBI International Project Development Vice President Mark Yancey, who did project development for the plant, the company spent about $1 million just for the right to use the water; sourcing the water was a separate endeavor.

Years of drought have made aquifer resources even more important in the Plains states. Now that ethanol has moved into all corners of the aquifer people are starting to express concern over the industry's impact. Ethanol brings an increased demand for corn, which must be irrigated, and production of the fuel also requires significant amounts of water.

Like many industrial processes, water is vital to ethanol production. The majority is used in the cooling process; the amount used can be influenced by the quality of the water, Yancey says. The production process uses between 3 to 5 gallons of water for every gallon of ethanol produced. In the past few years, the lack of water has stopped the development of some plants. Proposed plants from Florida to northern Minnesota to California have faced opposition from those concerned about the facilities' water use. "Regulatory agencies and the public are more aware of the volume of water required," Hume says. "Opposition at public meetings has certainly increased in the past few years compared with when the industry first took off—you might have a few residents who would be concerned about the impact a plant could have on their water supply. In general, the industry has become more aware of possible oppostion and the importance of water for plant operations." Some of the awareness likely comes from media coverage of recent reports about ethanol's water requirements.

A report issued in October by the National Research Council titled "Water implications of biofuels production in the United States" analyzed the potential impacts on water quality and supply from increased use of corn for ethanol production. The NRC formed a committee to look at how shifts in the nation's agriculture to include more energy crops, and potentially more crops overall, could affect water management and long-term sustainability of biofuels production. It found that an increase in ethanol production from corn could significantly impact water quality and availability unless new practices are employed.

The report acknowledged that the water consumed in the ethanol production process is similar to most other industries, but could still substantially affect local water supplies. It estimated that a 100 MMgy plant would consume as much water as a town of 5,000 people, using the national average water use per person per day of 180 gallons. "Biorefineries themselves generate local, but often intense, water supply challenges, while irrigated agriculture can generate regional-scale problems," the report says. "If, however, the agriculture is rain-fed, water for the biorefinery may be the primary source of groundwater or surface water extraction in the area. Compared to the water incorporated in the feedstock, water use for the biorefineries is quite small." The report concluded that producing 1 gallon of ethanol from irrigated corn requires 780 gallons of water, using statistics from 2003 when 2,100 gallons of irrigation water was used to produce a bushel of corn, which yielded 2.7 gallons of ethanol. This number doesn't include the water required to make the ethanol, and is actually about 200 times greater than the 4:1 water to ethanol ratio. Yancey confirms these findings. "The water used to produce ethanol at a 100 MMgy plant is equal to one center pivot—1,000 gallons per minute," he says.

Growing biofuels crops in areas with limited water supplies is a major concern, the report says. According to the NRC, "the committee found that agricultural shifts to growing corn and expanding biofuels crops into regions with little agriculture, especially dry areas, could change current irrigation practices and greatly increase pressure on water resources in many parts of the United States." Biofuels crop irrigation could compete with, or even be constrained by, regional water demands for drinking, industry and other uses. "In the next five to 10 years, increased agricultural production for biofuels will probably not alter the national-aggregate view of water use," the report reads. "However, there are likely to be significant regional and local impacts where water resources are already stressed."

The Ogallala aquifer is certainly stressed. "This aquifer is currently being pumped at a rate of more than 1.5 billion gallons per day for agriculture, municipalities, industry and private citizens," the report reads. "Thus, 15 million gallons per day for bioethanol would represent only 1 percent of total withdrawls. But it is an incremental withdrawal from an already unsustainable resource. Current water withdrawals are much greater than the aquifer's recharge rate (about 0.02 to 0.05 foot per year in south-central Nebraska …), resulting in up to a 190-foot decline in the water table over the past 50 years. It is equivalent to ‘mining' the water resource, and the loss of the resource is essentially irreversible."

The Environmental Defense study looked at the Ogallala aquifer as a "microcosm of the environmental concerns that may accompany rapid and unplanned expansion of biofuels production." According to the report, the aquifer supports the majority of irrigated agriculture in the southern Great Plains. "However, in recent decades it has experienced substantial water table declines in areas where rates of groundwater pumping have far exceeded rates of replacement," the report says.

The report found that the water demands for individual plants from ethanol processing and feedstock production aren't exceptionally higher than other industrial or agricultural users. However, the construction of new plants in areas where water is already scarce can impact the level of the aquifer. "Water demands from new ethanol plants in areas of Ogallala aquifer depletion may reach 2.6 billion gallons per year for corn-to-fuel processing alone, and between 59 [billion] and 120 billion gallons per year for increased water demand if there are local increases in irrigated corn production," according to the study. Interestingly, the region is experiencing ethanol production growth in areas where water resources are most stressed. The report points to southwest Kansas and the Texas panhandle, where several plants are proposed or under construction, as areas with the highest depletion, defined as within 50 miles of aquifer zones where water tables have dropped by more than 10 feet between 1980 and 1996.

Other Water Users
The Environmental Defense report didn't go over very well with the Nebraska Corn Board. "It made for sensational headlines and is just the latest in a series of attacks on corn and ethanol producers in regard to water," said Jon Holzfaster, a farmer and chairman of the board. "Those who want to blame the expansion of ethanol for increased water usage are ignoring the fact that corn is going to be produced in Nebraska, whether or not there is an ethanol industry. And that those same acres will likely be irrigated whether they are growing corn, soybeans or any other crop." Holzfaster compared the water used to raise corn to that used to water homeowner's lawns and golf courses. "It is estimated that it may take around 1,750 gallons of water to produce a bushel of corn," he said. "That sounds like a lot, but did you know it takes 684,000 gallons of water per acre per year to irrigate a golf course? And that, on average, a homeowner uses 21,600 gallons to water his or her lawn each year?" The NCGA has also found it useful to put the numbers in perspective. Based on USGS statistics, NCGA Chief Executive Officer Rick Tolman points out that it takes 1,851 gallons of water to refine a barrel of crude oil and 1,500 gallons to produce a barrel (42 gallons) of beer.

Regardless of these justifications, Environmental Defense advocates for policy changes that would encourage sustainable ethanol development. "Current biofuels policy makes few distinctions between different biofuels production pathways," the group says. "But plant location, production techniques and choice of feedstocks strongly influence the environmental footprint of ethanol production." Ideal policy changes, which would by nature need to be local and regional, would guide ethanol production toward more sustainable locations by making local approval of ethanol plant siting contingent on analyzing the impacts on water resources in areas of existing water scarcity. "Local agencies should be careful to consider indirect effects of ethanol in driving new irrigated cropland acres as well as calculations of water use directly for ethanol plant operation," Environmental Defense says.

Anduin Kirkbride McElroy is an Ethanol Producer Magazine staff writer. Reach her at [email protected] or (701) 746-8385.