Upper Delta Water Resources
Following the New Madrid Earthquakes of 1811 and 1812, much of Southeast Missouri, Northwest Tennessee, and Northeast Arkansas became swamp land because of the collapse of the natural tributaries into the Mississippi River. The region became overgrown with Cypress trees and water grasses. Today, the region is a fertile agricultural region with an elaborate system of man-made drainage ditches running through the Missouri Bootheel and SE Arkansas.
Oxbow lake from Mississippi River
Groundwater Aquifers. A Missouri Department of Natural Resources study found that despite increased water use from irrigating rice and other crops in the Missouri Bootheel, there has been no net decline in the alluvial aquifer in the region since the first water-level monitoring began in 1956. For more information download NDNR Report 46. Groundwater Resources of Missouri
|Aquifer||Thickness||Irrigation well yield|
|SE Lowlands Alluvial||0 to 300 feet||500 to 3,000 gpm|
|Wilcox and Claiborne||0 to 1,250 feet||200 to 1,700 gpm|
|McNairy||200 to 2,000 feet||150 to 750 gpm|
The SE Lowlands alluvium aquifer covers about 3,600 square miles and was laid down by the ancestral Mississippi and Ohio Rivers. The alluvium is the primary aquifer used for irrigation in the region and supplies most of the domestic water and much of the municipal and industrial waters. Although most irrigation wells tapping the alluvium yield about 1,000 gal/min., yields of more than 3,000 gal/min have been reported. This aquifer is so prolific that most irrigation wells are only 70 to 100 feet deep, even though the alluvium is generally much thicker. The quality of the water is excellent for crop production and is extensively used in furrow and center pivot irrigation systems. However, the high iron content in the water has caused problems in drip irrigation systems when the iron precipitates in the emitters.
The Wilcox and Claiborne group of aquifers underlies about 2,200 square miles of the area. This group crops out, or is exposed at the surface, over about 100 square miles on the Crowleys Ridge and Benton Hills. This group consists of up to 1,400 feet of unconsolidated or loosely consolidated sand and clay. This aquifer, which is reported to yield more than 1,500 gal/min in some areas, supplies many municipal systems.
The McNairy Formation, which is locally called the "Ripley Sand," underlies about 3,000 square miles and crops out over about 125 square miles on the Crowleys Ridge and Benton Hills. This formation, which consists of sand, sandy clay, and clay is reported to yield more than 700 gal/min. The high artesian pressure, very low hardness, and low iron concentration of the water makes this aquifer attractive for municipal supplies even though this aquifer may occur at considerable depths. Source: Luckey and Fuller, USGS Open File Report 79-421