The Mississippi River Valley alluvial aquifer is a water-bearing assemblage of gravels and sands that underlies about 32,000 square miles of Arkansas, Kentucky, Louisiana, Missis-sippi, Missouri, and Tennessee. Pumping of groundwater from the alluvial aquifer for agriculture started in the early 1900s in the Grand Prairie area for the irrigation of rice and soybeans. From 1965 to 2005, water use in the alluvial aquifer increased 655 percent. In 2005, 6,242 million gallons per day of water were pumped from the aquifer, primarily for irrigation and fish farming. Water-level declines in the alluvial aquifer were documented as early as 1927. Long-term water-level measure-ments in the alluvial aquifer show an average annual decline of 1 foot per year in some areas.