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IGWS Groundwater Resources

Beneath Iowa's land surface is a vast, natural storage and distribution system for groundwater, a resource that supplies over 80% of Iowans with their drinking water supplies. This resource is available through wells drilled into river valley sands and gravels, into other sand and gravel bodies buried within glacial deposits, and into the deeper limestone and sandstone strata beneath the state.

Over 35,000 sets of samples have been collected from the state's well drillers and contractors. These samples form a valuable "library" and are the basis of much of our understanding of Iowa's subsurface geologic and hydrologic setting. Thousands of logs prepared from these samples are available in our office or via electronic databases.

Water Supply  

The Survey provides information on the availability of groundwater supplies statewide. Given a specific geographic location, a water-well forecast can be prepared summarizing the available groundwater sources, the anticipated yields from existing aquifers, the quality of the water supply, the sequence of geologic materials to be encountered in drilling, and appropriate advisories on well construction or potential contamination problems. This information can be obtained by letter or office visit, over the phone, or by electronic pathways. More information is available online at:

Private Well Construction
Well Forecasting and Aquifers in Iowa

Most of the information available on the natural water quality of Iowa's groundwater concerns major chemical constituents, such as dissolved solids, hardness, and major ions such as sulfate, sodium, and iron. Over the past decade, additional information has become available on water quality related to agricultural contaminants such as nitrate and pesticides. Less information is available on trace metals, radionuclides, and organic chemicals. Information on the water quality of the major aquifers can be found in many of our publications, and individual analyses from municipal wells can also be obtained. More information is available online at: 

Alluvial Aquifers
Bedrock Aquifers
Iowa's Municipal Water-Supply Inventory (MWSI)
Regional and County Groundwater Resources
Water Quality and Agriculture 

Well Problems  

Water wells are a fact of life for rural dwellers, municipalities, and industrial users in Iowa. With thousands of well records from across the state on file, the Survey can forecast geologic and hydrologic conditions for people needing to drill a new well or needing to solve problems such as loss of yield or changes in water quality in existing wells. Problems in individual wells depend not only on the natural water quality of the aquifer, but on well siting, construction, and well history. For further information, contact the Survey at 319-335-1575.

Additional advice on water quality problems can be obtained from the State Hygienic Laboratory at the University of Iowa at 319-335-4500. They have a variety of publications on water quality and treatment. Another source is the Iowa State University Cooperative Extension Service office (515-294-4576), which also has publications on water quality problems and their treatment. 

Catalog of Water-Well Databases 

The Survey maintains an extensive collection of data that can be used to evaluate water resources and environmental impacts to water resources in Iowa. As with most organizations that deal with large quantities of information, we are making the transition to electronic data management. During this transition, databases that were formerly managed as paper files are being converted to electronic files. Substantial overlaps may occur between the contents of various databases. We are working to resolve these overlaps and potential conflicts, but this is a very large, time-consuming task.