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IGWS - Des Moines River Aquifer

Des Moines River Aquifer

The Des Moines River aquifer consists of sand and gravel deposited by the Des Moines River. A segment of the Des Moines River aquifer, which covers parts of Emmet and Palo Alto counties, was selected for a detailed hydrogeologic study (Figure 1). The primary objective of this study was to evaluate the potential impact of a new Iowa Lakes Regional Water wellfield near Osgood (Osgood wellfield) on nearby irrigation wells.

Figure 1. Extent of Des Moines River aquifer study area in Palo Alto and Emmet counties.

In the study area, the Des Moines River aquifer consists of sand and gravel deposits ranging in thickness from 6 to over 50 feet. Cobble and boulder zones are found in locations throughout the study area and produce large quantities of water. The sand and gravel is overlain by 2 to 6 feet of fine-grained sediments consisting of silt and silty sand and underlain by glacial till.

The Des Moines River aquifer supplies up to 400 million gallons of water per year to users in the study area. Current users include 14 irrigation water use permits (24 known irrigation wells) and two existing public water use permits (City of Emmetsburg and City of Graettinger). The proposed Iowa Lakes Regional Water Osgood wellfield involves six wells that will remove an additional 539 million gallons of water per year.

A computer model simulating the effects of a severe drought found adequate water resources are available to meet the Iowa Lakes Regional Water Systemís proposed permitted withdrawals in the Des Moines River aquifer. However, cooperation would be necessary from both Iowa Lakes Regional Water and the irrigators to maintain water supplies during a severe drought.

Adjustments in pumping cycles and rotating active and inactive wells may be necessary. The irrigation wells may also need to pump during the night when water demand is lower for the Osgood wellfield.


Des Moines River Aquifer