In the late 1980s, a lengthy drought across Central Illinois left lake levels dangerously low. This was especially problematic for the City of Bloomington, which receives its water supply from Lakes Bloomington and Evergreen.
The city was unable to dilute pollutants discharged by farms into the lakes’ tributaries. One of those pollutants, nitrates, rose to concentrations above the federal Environmental Protection Agency (EPA) limit of 10 milligrams per liter, according to the Bloomington Water Department. While those levels did not harm adults, ingestion of extremely high concentrations of nitrates by infants under 6 months old could be fatal.
“The city entered into an agreement to reach EPA-approved levels within 10 years, and we’ve stayed in accordance since that time,” said Rick Twait, superintendent of water purification for the City of Bloomington.
Twait credits the change to Bloomington’s decision to partner with Illinois State and the McLean County Soil and Water Conservation District. Almost 30 years later, the University’s faculty and students have dedicated untold hours to helping the city enhance its water quality. In turn, the students have gained real-world experiences with state-of-the-art equipment.
Currently, Illinois State is in the second cycle of a two-year $86,000 renewable grant through the City of Bloomington to conduct applied research at four stream sites. Under the guidance of faculty members from the School of Biological Sciences and the Department of Geography-Geology, Illinois State students monitor the streams, conducting measurements on water levels, on water haziness due to erosion, and on the nitrate and phosphorus concentrations.
One of the students working on the project is Joe Miller. The hydrogeology master’s student is studying how naturally occurring processes, like plant uptake—the absorption of nutrients by plants—can affect the concentration of harmful pollutants in groundwater that escape crop fields. Nitrate, an ingredient in synthetic fertilizers, is the main focus of his research.
“Previous research has shown that only 50 percent of the nitrogen in synthetic fertilizers is used by crops,” Miller said. “The remaining half leaves the field and impacts surrounding areas.”
Problems arise once nitrates infiltrate watersheds. In the case of Bloomington, 80–90 percent of the streams feeding the city’s reservoirs are surrounded by farmland. As a result, these tributaries carry fertilizer nutrients, primarily nitrates and phosphorus, to Lakes Bloomington and Evergreen, which provide drinking water to 80,000 residents.
“Illinois State’s faculty and students have conducted applied research in our tributaries that our small crew never could have, and the solutions we’ve enacted have prevented us from needing multimillion dollar treatment facilities to remove nitrates,” Twait said.
The watershed research has raised the profile of the University’s hydrogeology program, one of only four in the U.S. to offer undergraduate and graduate-level degrees in the discipline, and has attracted innovative students like Miller, a native of Pennsylvania.
“What appealed to me about this work was the interplay between the physical geology, hydrogeology, and the biology of the region,” Miller said. “It also gave me a chance to explore water quality, a topic I’m really interested in.”
Miller’s collection site is across a road from farmland and alongside a tributary for Lake Evergreen.
Once a week, Miller sets up a 24-hour sampler, a device that collects groundwater each hour. He then runs the samples on an ion chromatograph, an instrument that helps him identify the changes that occurred in nitrate concentrations. He also accounts for light intensity, water level, and groundwater temperature over the cycle.
“These factors help me to tease out what is really going on,” Miller said. “My scientific opinion going into this was that plant uptake through photosynthesis has the largest impact on nitrogen concentration. However, there are other possibilities such as de-nitrification by microorganisms, physical processes, and even evaporation.”
The Illinois Water Resources Center, a nonprofit based at the University of Illinois at Urbana-Champaign, is funding Miller’s research through a $10,000, yearlong grant. The grant is being administered by Professor Eric Peterson, a hydrogeologist in the Department of Geography-Geology. He said Miller’s work is filling an important gap.
“Previous lab-controlled studies have shown that nitrate concentrations in the soil change based on the daily photosynthetic cycle of plants,” said Peterson. “However, when you’re working in the field, there are so many variables that are uncontrollable. That’s why Joe’s results will be important.”
Miller’s research is significant for another reason. While Illinois possesses some of the richest soils in the world, they do not drain effectively due to dense clay in the ground. To prevent crops from drowning in groundwater, Midwestern farmers installed ceramic drain tiles leading to waterways beginning in the late 1800s. The approach resulted in unintended consequences decades later.
“Once synthetic fertilizers became common practice in the 1960s, these drains acted as freeways for nutrients to reach streams,” Peterson said. “As a result, water is prevented from undergoing the natural processes that occur in soils that would normally remove nitrates and other solutes.”
In an effort to re-introduce some of these processes, the city moved the drain tiles that were leading to the tributary next to Miller’s collection site. The nutrient-rich water is now being returned to the soil before it reaches the stream.
Better water management practices resulting from research like Miller’s work are needed across the Midwest, particularly Illinois, Peterson said. The state accounts for approximately 20 percent of the harmful nutrients found in the Gulf of Mexico each year. When the runaway compounds hitch a ride south aboard the Mississippi River, they spawn algal blooms, which are blamed for the gulf’s growing “dead zone.”
“The problem comes when algal blooms die off,” Peterson said. “They require oxygen to decompose, and they take it from the water. Without oxygen, nothing else can survive, and that results in hypoxia, fish kills, and dead zones.”
Reversing Illinois’ contributions can by itself improve the Louisiana fishing industry, the second largest producer after Alaska, according to the National Oceanic and Atmospheric Administration (NOAA).
“Research like Joe’s helps to identify best management practices that can be applied to reduce the problems we’re starting to see in large bodies of water and reduce costs to clean them up.” Peterson said.
Miller is using his research for his thesis, which he plans to publish. He hopes it will help hydrogeologists uncover next-level questions, like which plants remove the most nitrates from groundwater. At the midpoint of his research, Miller believes this experience has already caused him to change his career aspirations.
“I entered this program thinking I wanted to be an environmental consultant, where I would implement others’ research,” he said. “Now I’m leaning toward a government research position. I want to create the best practices.”
For more information about Illinois State’s water research project, visit waterresearch.IllinoisState.edu.
Tommy Navickas can be reached at tjnavic@IllinoisState.edu.