Illinois possesses one of the most extensive and interconnected river systems in the United States. Major waterways including the Illinois River, Chicago River system, Kaskaskia, Sangamon, and LaMoine flow through densely populated urban areas, intensive agricultural landscapes, and industrial corridors before joining the Mississippi River. This hydrological profile makes Illinois both a significant contributor to, and a downstream recipient of, microplastic pollution.
The state’s combination of major municipal wastewater treatment infrastructure, intensive row-crop agriculture with widespread use of plastic agricultural products, and substantial urban impervious surfaces create micro and nanoplastics (MNP) sources that few other regions match.
The McCormick, et. al (2016) study on nine Illinois rivers established that wastewater treatment plant (WWTP) effluent is a significant point source of microplastic to urban streams, with concentrations consistently elevated downstream of discharge points. This work has informed subsequent research efforts across the state.
Environment Illinois and allied organizations have undertaken expanded statewide sampling projects in 2025 and 2026, surveying microplastic presence across dozens of rivers, lakes, and streams. While comprehensive results are still being compiled, preliminary findings confirm the pervasive presence of MNPs across Illinois water bodies of all sizes and types.
Regional context further reinforces the scale of the problem. A survey by Environment Minnesota found microplastics at every single site studied across the upper Midwest, confirming that contamination is not limited to major urban waterways but extends throughout the region’s freshwater systems. Illinois operates hundreds of municipal wastewater treatment plants. Even high-efficiency plants release significant quantities of MNPs, particularly fibers and fragments. And as a leading agricultural state, Illinois’s extensive use of plastic mulch, silage wrap, irrigation tubing, and polymer-coated fertilizers introduces MNPs directly into farm soils that wash into waterways. In industrial corridors, pre-production plastic pellets, processing residues, and industrial wastewater contribute to MNP loading. Tire wear particles, litter fragmentation, and atmospheric fallout are collected by stormwater systems and discharged, often untreated, into receiving waters.
Macomb, the county seat of McDonough County and home to Western Illinois University, is situated in west-central Illinois within the La Moine River watershed. The East Fork LaMoine River watershed, which directly encompasses the Macomb area, covers approximately 223 square miles across Hancock, McDonough, and Warren Counties. The LaMoine River flows into the Illinois River, which in turn joins the Mississippi River, establishing a direct hydrological connection from Macomb to the Gulf of Mexico.
Most of the land cover in the East Fork LaMoine River watershed is cultivated crops, with urban development concentrated primarily in and around Macomb. This agricultural dominance, while central to the regional economy, creates conditions that compound water quality challenges.
The Illinois Environmental Protection Agency (IEPA) has placed several segments of the watershed on the state’s 303(d) list of impaired waters. The list includes the East Fork of the LaMoine and Drowning Fork. The IEPA total maximum daily load (TMDL) assessment identifies the following pollutant sources within the watershed. There are three municipal wastewater treatment plants (Bardolph, Bushnell West, and Good Hope) plus Macomb’s wastewater infrastructure discharge treated effluent which discharge into the watershed. As the McCormick et al. study demonstrated, WWTP effluent is a primary point source of microplastics in Illinois rivers. The second identified sources are crop production, animal agriculture, agricultural tile drainage, and septic systems, all contribute to nutrient loading, sedimentation, and—by extension—microplastic introduction.
While much public attention focuses on urban sources of microplastics, agricultural landscapes like those surrounding Macomb harbor significant and underappreciated MNP sources. Used to retain moisture and suppress weeds, mulch film degrades in situ, releasing fragments directly into soil. Drip irrigation systems use extensive polyethylene and PVC tubing that degrades over time under UV exposure. Plastic wrapping used in livestock feed storage contributes to on-farm plastic waste that can fragment and enter waterways. Controlled-release fertilizers use polymer coatings that break down in soil, adding microplastic directly to agricultural land. Municipal biosolids applied as fertilizer contain concentrated MNPs retained during wastewater treatment, effectively returning microplastics to the land. The Nature Medicine 2025 review by Lamoree et. al, specifically identified plastic-film mulching as a practice that raises food safety concerns, as MNPs in agricultural soil can absorb and desorb pesticides and may be taken up by crops.
Western Illinois University is positioned to play a valuable role in regional microplastic research. University departments in biology, chemistry, environmental science, and geography have the capacity and local knowledge to conduct watershed-scale MNP monitoring, characterize agricultural sources, assess ecological impacts on local aquatic communities, and engage students in citizen science. Given that no published microplastic-specific study has yet focused on the LaMoine River system, this represents a significant research opportunity.
It is important to remember that every microplastic particle that enters the East Fork LaMoine River near Macomb has a downstream trajectory: the LaMoine flows into the Illinois River, which joins the Mississippi River, which discharges into the Gulf of Mexico. Local contamination in McDonough County is not merely a local problem—it feeds directly into a continental-scale transport system that delivers microplastics to one of the world’s largest marine ecosystems.
What can individuals do? Choose reusable bags, bottles, containers, and utensils. Avoid heating food in plastic containers. Instill external filters (e.g., Filtrol, PlanetCare) or washing bags (e.g., Guppyfriend) that can capture 80–90% of synthetic fibers before they enter the wastewater stream. Prioritize cotton, wool, linen, and hemp garments over synthetic polyester, nylon, and acrylic. Use activated carbon and reverse osmosis home water filters which can reduce MNP concentrations in drinking water. Use glass, stainless steel, or ceramic for food storage and cooking.
How can municipalities help? Advanced treatment technologies such as membrane bioreactors, disc filters, and dissolved air flotation can dramatically reduce MNP discharge in effluent. Green infrastructure (bioswales (vegetative channels), rain gardens, constructed wetlands) and enhanced stormwater treatment can intercept MNPs from urban runoff before they reach waterways. Address aging sewer systems to reduce combined sewer overflows that bypass treatment entirely.
How can farmers help? Transition from conventional polyethylene mulch film to certified biodegradable alternatives. Implement on-farm plastic waste collection, recycling, and proper disposal programs. Reduce reliance on polymer-coated fertilizers where alternatives exist. Install riparian buffer (vegetative plantings near the waters edge) zones to intercept agricultural MNP runoff before it reaches waterways. Conduct soil testing for MNP contamination on fields with long histories of plastic mulch use Community participation is essential for both monitoring and advocacy. Citizen science programs such as river cleanups with microplastic sampling, community water quality testing, and engagement with organizations like the Alliance for the Great Lakes, Prairie Rivers Network, and Environment Illinois empower residents to contribute to data collection while building political will for policy change. Schools and universities, including Western Illinois University, can integrate microplastic sampling into curricula, creating educational opportunities while generating valuable local data.
Conclusion
Microplastics and nanoplastics represent a uniquely challenging environmental and public health problem: they are ubiquitous, persistent, largely invisible to the naked eye, and increasingly linked to serious health outcomes in humans. The scientific evidence base has expanded dramatically in recent years, from the detection of MNPs in virtually every human organ to landmark studies associating them with a more than four-fold increase in cardiovascular risk and their accumulation in brain tumors.
The problem is global, but it is also deeply local. In western Illinois, the agricultural landscape surrounding Macomb generates microplastic contamination through sources that receive far less attention than their urban counterparts: plastic mulch, silage wrap, polymer-coated fertilizers, and WWTP effluent. Every particle that enters the East Fork La Moine River begins a journey through the La Moine, the Illinois River, and the Mississippi toward the Gulf of Mexico. Local contamination is inseparable from the continental and global microplastic burden.
Addressing this challenge will require action across all community segments: individuals reducing plastic use and installing laundry filters; municipalities upgrading wastewater treatment and managing stormwater; state and federal policymakers establishing monitoring requirements and discharge standards; farmers adopting biodegradable alternatives and collection programs; and researchers filling critical knowledge gaps about exposure, health impacts, and remediation technologies.
The presence of microplastics in our water, our food, our air, and now our blood and brains is not a future concern— it is a present reality. The question is not whether to act, but how quickly and how effectively we can respond.
Informed civic engagement, grounded in scientific evidence and local knowledge, is the essential foundation for the policy changes, infrastructure investments, and behavioral shifts that this challenge demands. The invisible threat of microplastics will only be addressed when communities, researchers, and policymakers make it visible and act accordingly.
