A new report by the U.S. Geological Survey shows that growing corn for biofuel production  is having unintended effects on water quality and quantity in northwestern Mississippi and the Gulf of Mexico.

The information is the result of key findings from a study assessing water quality in the Mississippi Delta, where more water is necessary to produce corn than to produce cotton, which requires increased withdrawals of groundwater for irrigation. “Because corn uses 80 percent more water for irrigation than cotton, exchanging corn for cotton will decrease water-levels,” says Heather Welch, author of the Geological Survey report.

The U.S. Department of Energy’s Biofuels Initiative, which was implemented in 2006, calls for the replacement of 30 percent of current levels of gasoline consumption with biofuels by 2030 and the reduction of ethanol costs to prices competitive with gasoline by 2012.

From a press release detailing the report:

Scientists [have] found that the conversion of cotton to corn acreage (comparing 2007 to 2002) is estimated to have increased the nitrogen load for the Yazoo River by 7 percent. The Yazoo River Basin has been identified as a contributor of nitrogen to the Gulf of Mexico. Levels of nitrogen in the Gulf of Mexico have resulted in low dissolved oxygen conditions which can impact fish and bottom dwelling organisms.

The release quotes Jeannie Barlow, Geological Survey hydrologist and coauthor of the study, saying that some streams in the area have remained dry for months during periods of low rainfall: “We are seeing a loss of habitat complexity, and lowered water levels have decreased baseflow to streams.”