The Water Survey collects data and conducts integrated modeling to understand the complex dynamics of surface water and groundwater systems and their interactions. These efforts guide statewide and municipal policy and practices in preserving and maintaining sustainable water resources.
Surface Water
Sediment collection and analysis
Sediment composed of clay, silt, and sand deposited on riverbanks and floodplains contributes to the mineral-rich soils of Illinois’ valuable farmland. Excess sediment in waterways, however, negatively affects water quality, aquatic habitats, navigation, recreation, and tourism.
The Water Survey has long been at the forefront of researching and monitoring sediment transport in Illinois. The Benchmark Sediment Monitoring Program, initiated at the Water Survey in 1981, provides long-term data from 15 monitoring stations sampled weekly across the state. The data are used to conduct research, produce reliable information for land and water resource planning and management, and identify watersheds with high sediment delivery rates.
ISWS also established sediment and nutrient monitoring networks to support the U.S. Department of Agriculture’s Conservation Reserve Enhancement Program (CREP), which works to reduce the amount of silt, sediment, and nutrients entering the Illinois and Kaskaskia Rivers. Monitoring began in five Illinois River Basin subwatersheds in 1999 and expanded to include four Kaskaskia River Basin subwatersheds in 2013. Today, this continued monitoring provides the long-term data needed to measure the success of CREP conservation practices in high-priority conservation areas. Learn more about our Illinois and Kaskaskia river watershed monitoring.
Sediment sampling for chemical and biological analyses helps to inform restoration and mitigation efforts and determine beneficial uses of dredged materials. ISWS scientists provide a wide range of sediment sampling capabilities through their Vibrocore program, in which they sample depths beyond the reach of the most common sediment sampling techniques. ISWS has used this technique to collect samples for the Illinois Department of Natural Resources (IDNR), the U.S. Army Corps of Engineers, and the Illinois State Geological Survey, among others.
In a recent project, scientists provided sample collection services for the Illinois Department of Transportation (IDOT) to help identify contaminated sediment and best management strategies for beneficial reuse or disposal of sediment dredged for bridge construction projects throughout the state.
Surface water quality
Phosphorus and nitrogen from agricultural land and cities are known to contribute excess nutrients to surface water systems. ISWS researchers have studied nutrient runoff from these sources for decades, but are more recently investigating in-stream processes, such as stream bed erosion, as well.
Scientists conducted in-stream surveys in agricultural tributary watersheds of the Kaskaskia River and are developing models to simulate the amount of erosion occurring and how much phosphorus runs off into water bodies. This information is used to evaluate the effectiveness of CREP and, more specifically, to find alternative placements of agricultural best management practices based on which sound watershed management plans can be developed to reduce sediment and nutrient runoffs.
Scientists have developed the Illinois Coastal Zone Water Quality Database (ICoastalDB), funded by the IDNR, to determine and analyze more than 200 water quality parameters in the Illinois coastal zone. Data for this project was collected from various agencies, programs, and projects, and compiled into the Illinois Data Bank to assess the status of water quality in coastal areas. In a recently completed IDNR-funded project, scientists conducted trend analyses of selected water quality constituents, including phosphorus and chloride concentrations, which are of particular concern for communities in the Illinois Coastal Management Zone.
Emerging surface water research
The surface water research team’s recent research projects include:
- Integrating artificial intelligence (AI) with physically based hydrological models to improve watershed modeling
- Examining water demand for the power generation sector in Illinois and across the nation, and developing approaches and models to explore climate change impacts on water demand by thermoelectric plants
- Integrating machine learning with process-based watershed models to explore sediment and nutrient dynamics
- Assessing landscape and in-stream contribution of phosphorus and sediment in agricultural watersheds
- Continued development of a modeling framework to evaluate the impact of agricultural conservation practices in CREP-eligible areas of the Illinois River basin and the Kaskaskia River watersheds
Groundwater
Groundwater quality
ISWS researchers sample groundwater for a variety of constituents to understand geochemical processes within aquifers. Numerous naturally occurring chemicals, such as arsenic, manganese, radium, barium, and others, and anthropogenic contaminants, such as chloride from road salt applications, nitrate from fertilizers and septic systems, and lead from service lines, pose health risks.
Recent examples of groundwater quality research include:
- Sampling domestic wells in Kane County to evaluate how chloride from road salt applications has accumulated in shallow aquifers
- Sampling monitoring wells in natural areas of Lake County to evaluate chloride, nitrate, arsenic, and sulfate in shallow aquifers
- Sampling domestic wells in Will County to assess the groundwater quality in the Silurian dolomite aquifer
- Studying microplastic contamination in karst terrain in Jo Daviess County
- Using isotopes to study the timing and extent of glacial recharge to the Cambrian-Ordovician sandstone system and its sources of salinity
- Developing computer models to simulate the accumulation of chloride from road deicers over 30 years in the shallow aquifer of Will County
Real-time data collection from aquifers
More than 370 dedicated monitoring wells track how groundwater levels change through time in the state’s major shallow and deep aquifers. Groundwater levels change in response to seasonal rainfall and storm events, changes in river stage, pumping from high-capacity and irrigation wells, and land-use changes. These monitoring sites provide critical data to evaluate aquifer recharge, research groundwater-surface water interactions, and support long-term water supply planning for Illinois aquifers.
Around 155 of these monitoring wells track water levels hourly in real time. Monitoring groundwater in real time provides data to update models, identify seasonal and long-term trends, and understand the effects of human-made changes on land and water resource management. This information is key in projecting future water supply and demand scenarios. ISWS researchers receive financial support from water authorities, municipalities, private entities, and the IDNR to manage various monitoring sites.
Some monitoring network highlights:
- The Imperial Valley Water Authority sponsors the longest-running monitoring network at ISWS, consisting of 19 raingages and 18 groundwater observation wells, which began operating in the early 1990s. These monitoring sites continue to gather observations to update the Mahomet aquifer groundwater model. This data enables a better understanding of rainfall distribution in the area and how precipitation contributes to recharge of the Mahomet aquifer. Learn more about our Imperial Valley Precipitation and Groundwater Monitoring Network.
- Through other locally funded networks, such as the City of Decatur and Kane County gage stations, scientists can assess seasonal and long-term trends in aquifers, measure contaminants, check on the aquifers’ response to higher water demand during summer and drought periods, and create and update maps.
- The IDNR water supply planning programs support monitoring networks that are not as easily funded by local entities, such as the deep Cambrian-Ordovician sandstone aquifer system and the Green River Lowlands, which extend to multiple counties and have regional cones of depression that are essential to monitor.
Explore monitoring well locations and data with our interactive Illinois Groundwater Monitoring Network map or read more about our groundwater monitoring networks.
Emerging cross-disciplinary research
Hydrogeology of fault zones
Subsurface geologic structures and fault zones can affect how groundwater flows through aquifer systems. For example, in Northern Illinois, the Sandwich Fault Zone acts as a barrier to groundwater flow, exacerbating water supply problems in Kendall and Will counties as communities draw down the sandstone aquifer.
Sampling of water isotopes, mapping of water levels, and groundwater flow modeling have shed light on how groundwater flows through these complex features. Scientists have also conducted airborne geophysical and seismic surveys to map the 3D architecture and subsurface properties of the Sandwich Fault Zone in northern Illinois. This research will inform how other fault zones in Illinois affect groundwater flow and whether certain fault types can provide pathways for vertical fluid and gas migration, with implications for natural gas storage and carbon sequestration activities in the state. ISWS collaborates with ISGS on this research.
Interaction of surface water and groundwater
Leveraging 125 years of data and expertise, ISWS scientists use integrated hydrologic modeling to understand the interactions of all aspects of the water cycle — atmospheric water, surface waters, and groundwater — to address today’s most challenging hydrologic issues. This represents a major step forward from previous modeling at the Water Survey, in which we separated hydrologic research from management, such as surface waters being simulated separately from groundwater. Integrated hydrologic models foster a deeper understanding of processes and provide more powerful forecasting tools for analyzing both local and regional hydrologic systems.
Integrated surface water and groundwater flow modeling
Several of the defining principles and methodologies of modern groundwater flow models originated at ISWS. In the past few decades, ISWS modelers have used these modern tools to explore the pressing groundwater issues throughout the state. Now, researchers are exploring ways to push modeling capabilities into unprecedented territory, specifically by integrating groundwater and surface water models.
Our Computational Hydrology for Decision Support (CH4DS) team has been working on a water resource project with IDOT in the East St. Louis, IL area since the 1980s. Historically, this project has predominantly focused on regional groundwater, as rising groundwater levels rebounding from diminished industrial withdrawals threaten to inundate major interstate thoroughfares through the city.
In this project, staff are building a model that accounts for various hydrologic processes to provide IDOT with management solutions that optimize infrastructure systems and minimize unnecessary impacts on surrounding water resources. Newly constructed models of the American Bottom aquifer help ISWS researchers understand the region’s interconnected hydrology and the potential consequences for those living there.
The research group has been instrumental in elevating the model framework at ISWS to include high-performance computing and machine learning/genetic algorithms. The coupling of groundwater flow models with other types, such as surface water and reactive transport models, highlights this work.
Building on this work, ISWS is partnering with USGS for a large-scale study of the Illinois River Basin, including the Mahomet aquifer and Kankakee watershed. Scientists will use this evolved shallow aquifer model of Illinois within this basin to assess water availability and the fate and transport of nitrate. This partnership with USGS has a research goal to study harmful algal blooms in northern Illinois, focusing on how human land and waste management practices affect regional water resources.
Learn more about our computational hydrology work.