April 2023

Rounding a bend in a deep, otherwise dry creek bed, Tracy Branam called back, “It looks like we’ve found something, here, Sam!”

We’d been half-bushwhacking through the woods, following an ancient GPS unit and dubious verbal directions from a landowner, for more than 45 minutes, looking for a spring none of us had ever visited before. Finally, we’d found flowing water and traced it back to its source: a deep, bluish pool at the base of a limestone wall.

IGWS Volunteer Affiliate Sam Frushour collects a water sample from a spring in southern Indiana. | Sara Clifford, IGWS

IGWS retiree-turned-volunteer Sam Frushour splashed across the creek, picked his way along the edge of the rock face, and knelt to collect a sample as close as possible to where the water emanated from the ground. Had he hauled in his gear, he would have gone deeper. Frushour, 79, is still an avid cave diver. But he wasn’t doing that over this terrain.

While Frushour dunked the dipper, Branam deployed a wired sonde near the center of the blue pool. A handheld device recorded readings on pH, temperature, conductivity, dissolved oxygen, and oxidation reduction potential.

Temperature and conductivity confirm whether he’s looking at a spring or just surface drainage.

Dissolved oxygen and pH will tell what’s going on with the water before it reaches the surface: whether the aquifer feeding the spring has any large cavities or caves for air to interact with the water, and what the main type of water-mineral interaction is. Carbonate rocks like limestone and dolomite will buffer pH to around 7 or 8; if it’s a sandstone aquifer, pH typically will be less than 7, dissolved silicon will be high, and dissolved calcium and magnesium will be lower.

IGWS Research Scientist Tracy Branam holds a sonde that measures several types of data points. | Sara Clifford, IGWS

Sometimes, oxidation reduction is obvious from the smell: in exceptionally reduced waters, sulfur will occur as sulfide as opposed to sulfate. Sulfide is the “rotten egg” odor.

Next, Branam strung a tape measure along the flowing stream, marked a start point and an end point, and timed how long it took a leaf, a birch bark peel, or a twig—whatever wouldn’t swamp itself—to make it through the course. That was to approximate the stream flow, the volume of water per unit of time.

Recording the chemical properties of the water as well as the flow of the spring are important data points when charting Indiana’s water sources. This is a perennial spring—one that flows regardless of weather—as opposed to an ephemeral spring, which does not flow year-round. “If you’re in the driest time of the year and you’ve still got water (in your spring), it’s probably perennial,” Frushour said.

“What we’re trying to do is get (data on) as many perennial ones that are actually being used for something,” Branam explained. “Some of them are just nice because they’re big, like Orangeville Rise is the second-largest in the state. The Hamer Spring over at Spring Mill State Park is used to run the grist mill. And then some of them, we found some down here in Orange County which are the only source of water for a couple of homes. And then there’s the ones in Martin County where they’re kind of coming out of a pipe that people just walk up to and fill up jugs, so, we’re trying to monitor those springs particularly.

“But then there’s others that just aren’t used for anything.”

More than 100 Indiana property owners have given permission for the IGWS to sample water from their springs periodically. The IGWS has no enforcement power; the data collected is only for the sake of science. Still, reports are provided to the landowner that show whether their spring water contains certain biologic or chemical agents above recommended levels.

“A lot of times, people just use the water and don’t care what’s going on with it,” Frushour said.

In addition to telling IGWS scientists about the quantity and quality of water, springs data also gives clues about the underlying geology. As spring water gradually wears away the rock, the minerals in those rocks get taken up by the water, creating various compositions of “mineral springs” that used to drive the economies of many Indiana towns.

“Some of the ephemeral springs, especially out in Greene County where I live, are really valuable in terms of mapping stratigraphy,” Branam said. “They go through the sandstone, hit the limestone, but you can spot all along it and it’s almost a linear feature where limestone and sandstone meet. It makes it easier to map (the bedrock contacts).” That data also will be helpful as the IGWS develops hydrostratigraphic maps over the next few years to show the location and extent of aquifers.

IGWS Vounteer Affiliate Sam Frushour (left) and Research Scientist Tracy Branam take measurements at a cave spring in southern Indiana. | Sara Clifford, IGWS

Samples safely bottled and bagged, we meandered back through the briars and craggy streambeds, only taking one wrong turn on the way back before finding the barbed-wire fence we’d wriggled under on the way in.

“I’ve spent half my adult life wandering in the woods and getting paid for it,” Frushour remarked.

‘Pretty great way to spend a work day.