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Airborne Electromagnetic (AEM) Survey


In 2013, Exploration Resources International (XRI), under contract with the NRD, gathered airborne electromagnetic data in the northwestern part of the District. The project area included 99-square miles within a larger area, now called the Dwight-Valparaiso-Brainard Special Management Area.

The special management area designation by the NRD Board of Directors was in response to seasonal water level declines and, as hoped, the electromagnetic survey provided extensive information about the area's geology, aquifer characteristics and water in storage. The NRD's use of the data is on-going. This summary is intended to help landowners in the project area access data showing the depth to aquifer material, the thickness of the aquifer and other basic information. Much more, very technical information collected is also available for download.

The survey was flown by helicopter over three distinct blocks of land detailed on the map.

To access a full, interactive map with aquifer information about individual tracts of land, you will need to have a version of the Google Earth program installed on your computer. You can download the free version by clicking HERE. Now, with Google Earth installed, click

Interactive Map (5.5MB).
(This map provides a good indication of the availability of ground water, but the actual availability of ground water may vary significantly. The users' hardware capabilities may limit success in executing this link's intended actions.)

Google Earth will open and load the necessary map information. This may take a minute. Click any blue-shaded point on the map to see information about aquifer materials there. Tip: In the left column, in the Places tab, click on "Aquifer Properties" to highlight, then at the bottom of the tab click the "Adjust Opacity" square and adjust the slider to make underlying map features more visible!

This graphic explains information in the pop-up marker that appears when you click on the map.

The information available through the interactive map represents just a small portion of the data collected in the electromagnetic survey. The entire report from XRI is lengthy and geologically technical, but it is available for download in several sections. There is also a brief summary of the project by NRD Water Resources Specialist Dick Ehrman.

Download Options
(The users' hardware capabilities may limit success in executing this link's intended actions.)

A hard copy of the entire report from XRI is available at the:

Dwight Public Library, 120 North Second Street, open Wednesdays 3:30pm – 6:30pm and Saturdays 9:30am – 11:30am

Valparaiso Public Library, 300 West Second Street, open Tuesdays and Wednesdays 3:00pm – 8:00pm, Thursdays  1:00pm – 8:00pm and Saturdays 9:00am – Noon

East Butler Public Schools Library, 212 South Madison Street, in Brainard during school hours

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