by Andrew Gelderloos, Geology Specialist, Water Resources Division, Michigan Department of Environment, Great Lakes, and Energy
We can see most of the water cycle: rivers flow into lakes, clouds that drop rain and snow, and even water vapor from our breath on a cold day. But we can’t see groundwater, an essential component of the water cycle that supports the water we see and the life all around us.
Groundwater is, of course, water that is underground.
Groundwater is not an underground lake that you could swim in. Instead, it fills cracks and small pore spaces between sediments (like sand and clay) or within rocks. But, just like a lake holds a lot of water, there is a lot of water in underground aquifers.
This should surprise you. We see water everywhere we look in Michigan. But when 45% of Michiganders turn on their tap, the water that flows out is pumped from a groundwater well (Michigan Department of Environment, Great Lakes, and Energy, 2020).
Groundwater is not an underground river with ripples and rapids. Instead, it slowly flows between connected pore spaces and cracks. But, just like a river moves water across the landscape, groundwater can travel through an aquifer for miles before we see it at the surface.
If you take a drop of water from a stream and you want to trace the history of that drop back to when it fell as rain or snow, your journey will most likely take you underground, back through an aquifer, and then up to the surface where the precipitation landed.
This should surprise you. Intuitively, we all tend to visualize what we would be able to see: rain and snowmelt running off the ground surface and into a stream. But, “even during storm peaks, streamflow is composed mostly of water that has been stored in the landscape for weeks, months, or years” (Kirchner, Benettin, and van Meerveld, 2023).
Although we cannot see it, there is a lot of groundwater in Michigan. And it makes hidden connections throughout the state. Take a moment this month to reflect on how influential groundwater is to us, the lakes and streams in Michigan, our economies, and our ecosystems.
In the next two monthly newsletters, I’ll share what everyone needs to know about how groundwater moves so that you can help keep yourself, your neighbors, and your neighboring waters healthy.