Evaluation of Ground Water in LaGrange County

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Evaluation of Ground Water in LaGrange County

by Nancy R. Hasenmueller and Tracy D. Branam

Background

LaGrange County is located in northeastern Indiana and lies in the St. Joseph River Basin; the estimated population of the county in 2001 was 35,410 people (U.S. Census Bureau, 2004). Ground water is the source of 75 percent of the water withdrawn in the basin (Indiana Department of Natural Resources, Division of Water, 1987). Agriculture is the primary land use in the basin and nearly 78 percent of the acreage in the county is in farms.

Image of map of Indiana showing location of LaGrange County. In 2002, the Indiana Geological Survey at Indiana University began a project to evaluate the chemistry and relative age of the ground water in LaGrange County. The study was conducted to determine the levels of both naturally occurring and man-made contaminants in the ground water.

Water samples were collected from 50 wells in LaGrange County during the summer of 2002. These wells draw water from mixed deposits of gravel, sand, silt, and clay that were laid down by glaciers during the Ice Age.

Topeka fan terrain

Some sampled wells draw water from a glacial deposit composed of sand and gravel known as the Topeka fan. The crest or ridge of the Topeka fan extends from Lagrange southwestward to Ligonier. The sand and gravel deposits of the fan slope northwestward toward Emma Lake and the town of Topeka.

Modern-day Oliver Lake

Other sampled wells draw water from sand and gravel in the Oliver Lake glacial sequence. This sequence contains more clay and silt than the Topeka fan. Much of the clay and silt was deposited in glacial lakes that once covered parts of the landscape. Modern-day lakes in LaGrange County are much smaller remnants of these Ice Age lakes. The intent of the sampling was to acquire baseline water-quality data for the ground water in aquifers in these two very different glacial sequences. The wells range in depth from 10 to 220 feet.

Click the images below to view larger versions.

Image showing vertical section through the Topeka fan sequence. Click to view a larger version.

Vertical section through Topeka fan sequence (click image for a larger view)

Glacial terrain map showing 2002 sampling sites. Click to view a larger version.

Glacial terrain map showing 2002 sampling sites (click image for a larger view)

Image showing vertical section through the Oliver Lake sequence. Click to view a larger version.

Vertical section through Oliver Lake sequence (click image for a larger view)

This project is a cooperative study with the Indiana University Department of Geological Sciences and the LaGrange County Health Department, and is co-funded by the Indiana Department of Environmental Management.

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