Calumet Aquifer facts for kids

The Calumet Aquifer is like a giant underground sponge that holds water. It's an aquifer found beneath the land at the very southern end of Lake Michigan. This important water source is located under parts of Lake County, Indiana, Porter County, LaPorte County, and Cook County, Illinois.

Sadly, the Calumet Aquifer is known for having high levels of pollution. This pollution comes from old factories and industrial areas in the Calumet Region. To its south, it touches another underground water source called the Valparaiso Moraine Aquifer. To its north, it's bordered by Lake Michigan.

Where is the Calumet Aquifer?

The Calumet Aquifer is located under several cities. These include Gary, Hammond, and East Chicago.

This aquifer sits in loose layers of fine sand and glacial till. Glacial till is a mix of dirt and rocks left behind by ancient glaciers. It's found in a flat area called the Calumet Lacustrine Plain. Sometimes, you can also find layers of peat (decaying plants) and gravel within it. Because of these loose materials, the aquifer can easily get polluted from things on the surface.

People in the local communities usually get their drinking water from Lake Michigan. The Calumet Aquifer has not been used much as a main source of water.

How the Aquifer Gets Water

The area above the Calumet Aquifer gets about 36 inches of precipitation (rain and snow) each year. About 12 inches of this water soaks into the ground and recharges the aquifer. This means the aquifer gets refilled with fresh water.

The aquifer can hold a lot of water. About 12% of its total volume is water that can be released.

Aquifer and Rivers

The Calumet Aquifer is a groundwater aquifer. This means it helps supply water to local rivers and streams. It provides water to the Grand Calumet River and the Little Calumet River.

Sometimes, the rivers can also give water back to the aquifer. For example, when the Little Calumet River floods, its water level rises above the aquifer. Then, water from the river can flow into the aquifer. The Calumet Aquifer also gets water from the Valparaiso Moraine Aquifer to the south. This water travels through the bedrock system that lies beneath both aquifers.

Across most of its area, the aquifer is about 15 feet (4.6 m) thick with water. It usually lies about 15 feet (4.6 m) below the ground. In some places, it can be much thicker, reaching around 45 feet (14 m) of saturated thickness.

Different Parts of the Aquifer

Sometimes, the Calumet Aquifer is divided into two parts. These are the Calumet Aquifer itself and the Lacustrine Plain Aquifer. The Calumet Aquifer proper is a narrower strip along Lake Michigan. The Lacustrine Plain Aquifer lies underneath it in a deeper layer.