Bedrock Aquifers

In bedrock aquifers, large scale stresses on the rock will result in numerous fractures in the rock. When we drill a well into these rocks, the bore hole intercepts numerous fractures, allowing water to seep into the well.

Some sedimentary rocks also has some degree of primary porosity (groundwater will also be held within the pore spaces of the rock).

This illustration shows that bedrock aquifers are found in many regions throughout Michigan, but are primarily found in the eastern half of the Upper Peninsula and the south-central part of the Lower Peninsula. The "good" aquifers shown on the map are typically productive sources of reasonable-quality drinking water. The groundwater in these bedrock aquifers flows to the well through the pore spaces in the formation and along the fractures in rock.

The "marginal" aquifers exhibit highly variable productivity or poor quality water. "Marginal 1" aquifers are similar rock types to the "good" aquifers, but have restricted porous flow and

fracture flow. "Marginal 2"aquifers are very dense, hard rock types which only support limited fracture flow.

The unmarked areas of bedrock are either unproductive or contain non-potable (non-drinkable) groundwater. Virtually everywhere in Michigan, at depth, brine (salt) water occurs in the formations. This water contains large amounts of dissolved solids, and on average is 10 times saltier than sea water!

Access to bedrock aquifers depends upon the thickness of the drift that buries the bedrock. The thicker the drift, the more expensive it is to access a bedrock aquifer.

Institute of Water Research - MSU
Design by Alex Morese