Authored by Martha Roberts and Theodore Toombs of the Environmental Defense Rocky Mountain office and Dr. Timothy Male, senior ecologist with the Land, Water & Wildlife Program in the group's Washington, DC office, the report takes the form of a case study of the Ogallala Aquifer region.
One of the world's largest aquifers, the Ogallala Aquifer, also known as the High Plains Aquifer, is a vast, shallow underground pool of water located beneath portions of Colorado, Kansas, Nebraska, New Mexico, Nebraska, Oklahoma, South Dakota, Texas, and Wyoming.
The Ogallala Aquifer supports the majority of irrigated agriculture in the southern Great Plains. But the water table is declining in areas where rates of groundwater pumping have far exceeded rates of replacement. The region was also the center of Dust Bowl conditions in the 1930s.
The report warns that water withdrawals for growing corn and processing it to make ethanol fuel will put unsustainable pressure on the aquifer.
New corn ethanol plants currently under construction or planned will increase the region's ethanol production capacity by 900 percent, the report finds. The area currently hosts only five ethanol plants with combined production of 71.5 million gallons per year, but another nine plants, with 639 million gallons per year capacity, are currently under construction.
Each gallon of ethanol takes four gallons of water to produce, so the authors calculate that the nine plants under construction would increase groundwater withdrawals from some of the most depleted parts of the Ogallala region by an estimated 2.6 billion gallons per year.
'This dramatic expansion of ethanol production has substantial implications for already strained water and grassland resources in the Ogallala Aquifer region,' the authors say.
Additional water withdrawals will be required to grow the corn that will serve as feedstock for the ethanol production plants.
The report cites USDA National Agricultural Statistics Service surveys of irrigation rates showing that production of one bushel of corn consumes an average of 2,600 gallons of irrigation water in counties in or near areas of high Ogallala depletion.
According to this figure, if only 10 to 20 percent of the ethanol feedstock comes from newly planted irrigated corn acreage near the ethanol plants, water withdrawals from the most depleted parts of the Ogallala region would increase by approximately 59 to 120 billion gallons per year.
This increase is equal to up to 86 percent of the total irrigation water demand of the state of South Dakota and is comparable to the 76 billion gallons of water used annually by the one million customers of the primary water utility for Denver, Colorado, the report states.
Conversion of grasslands to cornfields is another likely result of the U.S. demand for ethanol, the report says. 'Conversion may be directly linked to ethanol expansion, as when grassland is converted to supply corn to a nearby ethanol plant, or more indirectly connected, as when grassland is converted to satisfy demand for livestock feed or export markets displaced by increasing use of corn for ethanol.'
The report calls for measures to 'mitigate the negative implications of biofuels production and create incentives for the cleanest production pathways.'
The authors praise California's Low Carbon Fuels Standard, which requires a 10 percent decrease in the carbon content of transportation fuels sold in the state by 2020. 'Such policies should also be paired with strong incentives for water and wildlife protection that should accompany any solely carbon-focused standard,' they recommend.
They are looking to the new farm bill now before the U.S. Senate to maintain or expand the federal Conservation Reserve Program 'in recognition of its critical role in maintaining vulnerable soil, water, and wildlife habitat resources.'
In addition, the report calls for a strong 'Sodsaver' provision in the farm bill that eliminates subsidy support for any crops planted on formerly untilled grasslands. This measure also is advocated by many other environmental groups.
The authors call on local and regional decision makers to strengthen and expand groundwater conservation efforts and also to guide ethanol production toward the most sustainable locations by making local approval of ethanol plant siting contingent on analyzing the impacts on water resources in areas of water scarcity.