This blog post was written by UW-Madison undergraduate Shayla Barrera-Skibinski, who worked at WGNHS as a Social Media and Geology Assistant from 2022-2024. Includes June 2024 update by Mel Reusche.
Where does our drinking water come from?
It is easy to take for granted the water flowing out of our taps. Drinking water is one of Wisconsin’s most precious resources, vital to all Wisconsinites, and as such, it is an important focus for many science teachers across the state. In partnership with the UW-Stevens Point Center for Watershed Science and Education and the Wisconsin Department of Natural Resources, WGNHS has led a water workshop for Wisconsin educators for more than a decade. Through these amazing educators, key information about Wisconsin’s water is shared with the people who live here (Figure 1).
We all notice the Great Lakes that border our state, however hidden under our feet lies the source of most of our drinking water: groundwater. As the term suggests, this water is stored in the ground. Rather than a giant underground lake, groundwater is stored in the tiny spaces between individual grains of sediment (gravel, sand, silt, clay), or within fractures of bedrock. Picture a bucket filled with baseballs: if you poured in water, it would fill in the spaces between the baseballs. When a large, interconnected network of these underground spaces is filled with water, it is called an aquifer. Earth scientists that research groundwater are called hydrogeologists; they study this amazing resource and provide information on water issues such as water quality and contamination and water quantity. Everyone who drinks water (hint, you!) can benefit from understanding where our water comes from and how to keep it potable and plentiful.
There are 4 major aquifers in Wisconsin that hold a whopping 1.2 quadrillion (or, in other words, 1.2 million billion) gallons of water within buried sediments and rocks. If this water was at the surface, it would cover the state in 100 ft of water! This can be hard to imagine, but in some ways the rocks beneath our state are like a giant sponge for groundwater. For many, thinking and learning about this concept starts in a classroom with our Wisconsin educators!
Visualizing underground water flow
We use models more often than we think: the weather forecast we check to prepare for rain, the spinning globes in our classrooms, and even model airplanes! Models are one of the greatest resources for visualizing complicated processes. There are physical models to represent a concept, like a globe, or digital systems which can rely on unique computer programs. Both are representations to help us understand complicated ideas that can be difficult to imagine. Using a model is a great way to help us think about groundwater and for this reason, a sand tank model is the focus of the workshops led by WGNHS and UW-Stevens Point.
The sand tank groundwater model used in the workshop is just one of the many models used to simulate groundwater transport. Upon first glance this model looks a lot like an ant farm (Figure 2). Different types of sediment are layered between two sheets of plexiglass, with a low point on top to represent a lake or river. “Wells” are drilled from the top of the model into various sediment layers within the sand-filled tank to represent wells extracting water from different aquifers. With this simple “slice” of the subsurface, the model can be used to showcase the potential movement of contaminants within and between aquifers. A contaminant is anything polluting the groundwater that can make it unsafe to drink. When working with the model, contaminants are represented by food-coloring dyes, which are added at multiple points along the model (i.e., within wells, on the surface). Then we can observe as the contaminant moves through aquifers and between subsurface layers in a similar manner to real-life.
To help add context to the groundwater model and the lesson plans introduced at the workshop, educators spend time at the workshop learning about the unique rocks and sediment that make up the Wisconsin aquifers (Figure 3). They learn how these rocks affect the distribution of water below us, and the current groundwater principles and research, that can be incorporated into their lessons.
Lasting impact on Wisconsin educators
The sand tank groundwater model workshop has been taught for nearly 15 years! As of the year 2024, the annual workshop continues with two offerings occurring in the month of April at UW-Stevens Point and at Upham Woods Outdoor Learning Center. Wisconsin educators are invited to apply for a spot in the workshop, where they will be guided on how they can incorporate their new knowledge and tools into future lesson plans. In addition, educators are offered sand tank groundwater models for their classrooms to share the physical models with students. Through these activities, the importance of understanding and protecting Wisconsin’s groundwater can be passed on to future naturalists, hydrogeologists, and Wisconsinites. Past participants of the workshop have shared their experiences with passing on knowledge to their students. From this group of participants:
90% agreed that the sand tank model was vital to learning about groundwater resources.
95% reported that their students were actively engaged in the sand tank model lessons.
80% of participants said that their understanding of groundwater improved.
90% felt more confident in sharing this knowledge with their students after the workshop.
The unique opportunity to use a physical model, and learn directly from groundwater experts, informs and empowers educators, and fosters deeper understanding for students. With this deeper understanding, the workshop grows awareness about the future of Wisconsin’s most precious resource.
From the educators
Participants from the 2022 sand tank groundwater model cohort shared their thoughts and hopes for their own classrooms, check out some of their responses!
Further reading and resources
Learn more about the workshop and how to apply here (Applications are open 2025)
Learn more about the Wisconsin aquifers here
Listen to a talk from Dr. Ken Bradbury about the hydrogeology of Wisconsin here