Geology topics

Research about Illinois

Source-linked reports with geographic coverage including Illinois.

At least 181 records · Page 10Linked to original sources

USGS2011

The path to a successful one-million tonne demonstration of geological sequestration: Characterization, cooperation, and collaboration

The development of the Illinois Basin-Decatur USA test site for a 1 million tonne injection of CO 2 into the Mount Simon Sandstone saline reservoir beginning in 2011 has been a multiphase process requiring a wide array of personnel and resources that began in 2003. The process of regional characterization took two years as part of a Phase I effort focused on the entire Illinois Basin, located in Illinois, Indiana, and Kentucky, USA. Seeking the cooperation of an industrial source of CO 2 and site selection within the Basin took place during Phase II while most of the concurrent research emphasis was on a set of small-scale tests of Enhanced Oil Recovery (EOR) and CO 2 injection into a coal seam. Phase III began the commitment to the 1 million-tonne test site development through the collaboration of the Archer Daniels Midland Company (ADM) who is providing a site, the CO 2 , and developing a compression facility, of Schlumberger Carbon Services who is providing expertise for operations, drilling, geophysics, risk assessment, and reservoir modelling, and of the Illinois State Geological Survey (ISGS) whose geologists and engineers lead the Midwest Geological Sequestration Consortium (MGSC). Communications and outreach has been a collaborative effort of ADM, ISGS and Schlumberger Carbon Services. The Consortium is one of the seven Regional Carbon Sequestration Partnerships, a carbon sequestration research program supported by the National Energy Technology Laboratory of the U.S. Department of Energy.

Illinois↗

USGS2011

Meeting CCS communication challenges head-on: Integrating communications, planning, risk assessment, and project management

The Midwest Geological Sequestration Consortium, Schlumberger Carbon Services, and Archer Daniels Midland has implemented a comprehensive communications plan at the Illinois Basin–Decatur Project (IBDP), a one million metric tonne Carbon Capture and Storage project in Decatur, IL, USA funded by the U.S. Department of Energy’s National Energy Technology Laboratory. The IBDP Communication Plan includes consortium information, funding and disclaimer citations, description of target audiences, media communications guidelines, paper and presentations guidelines, site visit information, crisis communication, on-site photography regulations, and other components. The creation, development, and implementation processes for the IBDP Communication Plan (the Plan) are shared in this paper. New communications challenges, such as how to address add-on research requests, data sharing and management, scope increase, and contract agreements have arisen since the Plan was completed in January 2009, resulting in development of new policies and procedures by project management. Integrating communications planning, risk assessment, and project management ensured that consistent, factual information was developed and incorporated into project planning, and constitutes the basis of public communications. Successful integration has allowed the IBDP to benefit from early identification and mitigation of the potential project risks, which allows more time to effectively deal with unknown and unidentified risks that may arise. Project risks and risks associated with public perception can be managed through careful planning and integration of communication strategies into project management and risk mitigation.

Illinois↗

USGS2011

Effects of biologically-active chemical mixtures on fish in a wastewater-impacted urban stream

Stream flow in urban aquatic ecosystems often is maintained by water-reclamation plant (WRP) effluents that contain mixtures of natural and anthropogenic chemicals that persist through the treatment processes. In effluent-impactedstreams, aquatic organisms such as fish are continuously exposed to biologically-activechemicals throughout their life cycles. The North Shore Channel of the Chicago River (Chicago, Illinois) is part of an urban ecosystem in which > 80% of the annual flow consists of effluent from the North Side WRP. In this study, multiple samplings of the effluent and stream water were conducted and fish (largemouth bass and carp) were collected on 2 occasions from the North Shore Channel. Fish also were collected once from the Outer Chicago Harbor in Lake Michigan, a reference site not impacted by WRP discharges. Over 100 organic chemicals with differing behaviors and biological effects were measured, and 23 compounds were detected in all of the water samples analyzed. The most frequently detected and highest concentration (> 100 μg/L) compounds were ethylenediaminetetraacetic acid and 4-nonylphenolmono-to-tetraethoxycarboxylic acids. Other biologically-activechemicals including bisphenol A, 4-nonylphenol, 4-nonylphenolmono-to-tetraethoxylates, 4- tert -octylphenol, and 4- tert -octylphenolmono-to-tetraethoxylates were detected at lower concentrations (< 5 μg/L). The biogenic steroidal hormones 17β-estradiol, estrone, testosterone, 4-androstene-3,17-dione, and cis -androsterone were detected at even lower concentrations (< 0.005 μg/L). There were slight differences in concentrations between the North Side WRP effluent and the North Shore Channel, indicating minimal in-stream attenuation. Fish populations are continuously exposed to mixtures of biologically-activechemicals because of the relative persistency of the chemicals with respect to stream hydraulic residence time, and the lack of a fresh water source for dilution. The majority of male fish exhibited vitellogenin induction, a physiological response consistent with exposure to estrogenic compounds. Tissue-level signs of reproductive disruption, such as ovatestis, were not observed.

Illinois↗

USGS2011

Using observed postconstruction peak discharges to evaluate a hydrologic and hydraulic design model, Boneyard Creek, Champaign and Urbana, Illinois

Boneyard Creek—which drains an urbanized watershed in the cities of Champaign and Urbana, Illinois, including part of the University of Illinois at Urbana-Champaign (UIUC) campus—has historically been prone to flooding. Using the Stormwater Management Model (SWMM), a hydrologic and hydraulic model of Boneyard Creek was developed for the design of the projects making up the first phase of a long-term plan for flood control on Boneyard Creek, and the construction of the projects was completed in May 2003. The U.S. Geological Survey, in cooperation with the Cities of Champaign and Urbana and UIUC, installed and operated stream and rain gages in order to obtain data for evaluation of the design-model simulations. In this study, design-model simulations were evaluated by using observed postconstruction precipitation and peak-discharge data. Between May 2003 and September 2008, five high-flow events on Boneyard Creek satisfied the study criterion. The five events were simulated with the design model by using observed precipitation. The simulations were run with two different values of the parameter controlling the soil moisture at the beginning of the storms and two different ways of spatially distributing the precipitation, making a total of four simulation scenarios. The simulated and observed peak discharges and stages were compared at gaged locations along the Creek. The discharge at one of these locations was deemed to be critical for evaluating the design model. The uncertainty of the measured peak discharge was also estimated at the critical location with a method based on linear regression of the stage and discharge relation, an estimate of the uncertainty of the acoustic Doppler velocity meter measurements, and the uncertainty of the stage measurements. For four of the five events, the simulated peak discharges lie within the 95-percent confidence interval of the observed peak discharges at the critical location; the fifth was just outside the upper end of this interval. For two of the four simulation scenarios, the simulation results for one event at the critical location were numerically unstable in the vicinity of the discharge peak. For the remaining scenarios, the simulated peak discharges over the five events at the critical location differ from the observed peak discharges (simulated minus observed) by an average of 7.7 and -1.5 percent, respectively. The simulated peak discharges over the four events for which all scenarios have numerically stable results at the critical location differs from the observed peak discharges (simulated minus observed) by an average of -6.8, 4.0, -5.4, and 1.5 percent, for the four scenarios, respectively. Overall, the discharge peaks simulated for this study at the critical location are approximately balanced between overprediction and underprediction and do not indicate significant model bias or inaccuracy. Additional comparisons were made by using peak stages at the critical location and two additional sites and using peak discharges at one additional site. These comparisons showed the same pattern of differences between observed and simulated values across events but varying biases depending on streamgage and measurement type (discharge or stage). Altogether, the results from this study show no clear evidence that the design model is significantly inaccurate or biased and, therefore, no clear evidence that the modeled flood-control projects in Champaign and on the University of Illinois campus have increased flood stages or discharges downstream in Urbana.

Illinois↗

USGS2010

Mineralogy and the release of trace elements from slag from the Hegeler Zinc smelter, Illinois (USA)

Slag from the former Hegeler Zn-smelting facility in Illinois (USA) is mainly composed of spinifex Ca-rich plagioclase, fine-grained dendritic or coarse-grained subhedral to anhedral clinopyroxenes, euhedral to subhedral spinels, spherical blebs of Fe sulfides, silicate glass, and less commonly fayalitic olivine. Mullite and quartz were also identified in one sample as representing remnants of the furnace lining. Secondary phases such as goethite, hematite and gypsum are significant in some samples and reflect surficial weathering of the dump piles or represent byproducts of roasting. A relatively rare Zn-rich material contains anhedral willemite, subhedral gahnite, massive zincite, hardystonite and a Zn sulfate (brianyoungite), among other phases, and likely represents the molten content of the smelting furnace before Zn extraction. The bulk major-element chemistry of most slag samples is dominated by SiO 2 , Al 2 O 3 , Fe 2 O 3 and CaO. The bulk composition of the slag suggests a high viscosity of the melt and the mineralogy suggests a high silica content of the melt. Bulk slag trace-element chemistry shows that the dominant metal is Zn with >28.4 wt.% in the Zn-rich material and between 212 and 14,900 mg/kg in the other slags. The concentrations of other trace elements reach the following: 45 mg/kg As, 1170 mg/kg Ba, 191 mg/kg Cd, 242 mg/kg Co, 103 mg/kg Cr, 6360 mg/kg Cu, 107 mg/kg Ni, and 711 mg/kg Pb. Zinc, as the dominant metal in the slags, is likely the most environmentally significant metal in these samples; Cd, Cu, and Pb are also of concern and their concentrations exceed US Environmental Protection Agency preliminary remediation goals for residential soils. Spinel was found to be the dominant concentrator of Zn for samples containing significant Zn (>1 wt.%); the silicate glass also contained relatively high concentrations of Zn compared to other phases. Zinc partitioned into the silicates and oxides in these samples is generally more resistant to weathering and therefore less leached when compared to the slag samples with lower bulk Zn concentrations where Zn is likely partitioned into volumetrically minor sulfides. This is confirmed by leachate tests that resulted in low leachate Zn concentrations for samples with Zn partitioned into spinel. In contrast, the concentrations of Zn and SO 4 are close to those expected from the dissolution of stoichiometric ZnS in leachates from samples in which the dominant host of Zn is suspected to be sulfides. The fact that Zn and other metals occur commonly as sulfides, which are more reactive than the silicates and oxides into which they dominantly partition according to other slag studies, indicates the Hegeler slag pile may be more of an environmental concern than other slag piles.

Illinois↗

USGS2010

Factors associated with hunter success for ducks on state-owned lands in Illinois, USA

Factors that influence hunter success for waterfowl are subject to varying levels of control by managers. The relative influence of these factors is poorly understood, but such information may be valuable to guide management actions intended to promote successful hunting and communicate management decisions to constituents. We used bag-check data to investigate factors influencing hunter success for mallards Anas platyrhynchos and other dabbling ducks (tribe Anatini) during the period 1981-2000 and 2002 at Illinois public waterfowl areas. Competing models of hunter success for mallards and other dabbling ducks included a negative association with average low temperature during the duck season (uncontrollable by managers) and positive associations with estimates of local and continental duck abundance, factors which we considered partially controllable by managers. Although a certain proportion of variation in hunter success for ducks cannot be directly influenced by managers, we suggest that programs and management efforts, which promote larger continental duck populations (e.g. Conservation Reserve Program) and local duck abundance (e.g. provide quality wetland foraging habitats), may positively influence hunter success.

Illinois↗

USGS2010

Development and analysis of a meteorological database, Argonne National Laboratory, Illinois

A database of hourly values of air temperature, dewpoint temperature, wind speed, and solar radiation from January 1, 1948, to September 30, 2003, primarily using data collected at the Argonne National Laboratory station, was developed for use in continuous-time hydrologic modeling in northeastern Illinois. Missing and apparently erroneous data values were replaced with adjusted values from nearby stations used as 'backup'. Temporal variations in the statistical properties of the data resulting from changes in measurement and data-storage methodologies were adjusted to match the statistical properties resulting from the data-collection procedures that have been in place since January 1, 1989. The adjustments were computed based on the regressions between the primary data series from Argonne National Laboratory and the backup series using data obtained during common periods; the statistical properties of the regressions were used to assign estimated standard errors to values that were adjusted or filled from other series. Each hourly value was assigned a corresponding data-source flag that indicates the source of the value and its transformations. An analysis of the data-source flags indicates that all the series in the database except dewpoint have a similar fraction of Argonne National Laboratory data, with about 89 percent for the entire period, about 86 percent from 1949 through 1988, and about 98 percent from 1989 through 2003. The dewpoint series, for which observations at Argonne National Laboratory did not begin until 1958, has only about 71 percent Argonne National Laboratory data for the entire period, about 63 percent from 1948 through 1988, and about 93 percent from 1989 through 2003, indicating a lower reliability of the dewpoint sensor. A basic statistical analysis of the filled and adjusted data series in the database, and a series of potential evapotranspiration computed from them using the computer program LXPET (Lamoreux Potential Evapotranspiration) also was carried out. This analysis indicates annual cycles in solar radiation and potential evapotranspiration that follow the annual cycle of extraterrestrial solar radiation, whereas temperature and dewpoint annual cycles are lagged by about 1 month relative to the solar cycle. The annual cycle of wind has a late summer minimum, and spring and fall maximums. At the annual time scale, the filled and adjusted data series and computed potential evapotranspiration have significant serial correlation and possibly have significant temporal trends. The inter-annual fluctuations of temperature and dewpoint are weakest, whereas those of wind and potential evapotranspiration are strongest.

Illinois↗

USGS2010

Hydrology, water quality, and causes of changes in vegetation in the vicinity of the Spring Bluff Nature Preserve, Lake County, Illinois, May 2007–August 2008

Agriculture and urbanization have altered the hydrology and water quality of the coastal wetland complex along the shore of Lake Michigan at the Spring Bluff Nature Preserve and Illinois Beach State Park in northeastern Lake County, Ill., and the adjacent Chiwaukee Prairie State Natural Area in southeastern Wisconsin. Culverts, roads, ditches, and berms installed within the wetland complex have altered the natural directions of surface-water flow and likely have increased the natural hydroperiod in the Spring Bluff Nature Preserve and decreased it in the northern part of the Illinois Beach State Park. Relative to presettlement conditions, surface-water runoff into the wetlands likely is greater in quantity and higher in concentrations of several constituents, including chloride, nitrate, phosphorous, and suspended sediment. These constituent concentrations are affected by a variety of factors, including the amount of agricultural and urban land use in the watersheds. Hydrologic, chemical, and biologic processes within the wetland communities reduce the concentrations of these constituents in surface water before the water discharges to Lake Michigan by as much as 75 percent for chloride, 85 percent for nitrate, 66 percent for phosphorous, and more than an order of magnitude for suspended sediment. However, concentrations of phosphorous and suspended sediment in surface water increased within parts of the wetland complex. Given these changes, the floristic quality of these wetlands has been altered from the historic condition. Specifically, Typha spp. and Phragmites australis occur in greater numbers and over a larger area than in the past. The spread of Typha spp. and Phragmites australis appears to be enhanced by anthropogenic alterations within the wetland complex, such as increased water levels and duration of inundation and, possibly, increases in the total concentration of dissolved constituents in water.

Illinois↗

USGS2010

Pier and contraction scour prediction in cohesive soils at selected bridges in Illinois

This report presents the results of testing the Scour Rate In Cohesive Soils-Erosion Function Apparatus (SRICOS-EFA) method for estimating scour depth of cohesive soils at 15 bridges in Illinois. The SRICOS-EFA method for complex pier and contraction scour in cohesive soils has two primary components. The first component includes the calculation of the maximum contraction and pier scour (Zmax). The second component is an integrated approach that considers a time factor, soil properties, and continued interaction between the contraction and pier scour (SRICOS runs). The SRICOS-EFA results were compared to scour prediction results for non-cohesive soils based on Hydraulic Engineering Circular No. 18 (HEC-18). On average, the HEC-18 method predicted higher scour depths than the SRICOS-EFA method. A reduction factor was determined for each HEC-18 result to make it match the maximum of three types of SRICOS run results. The unconfined compressive strength (Qu) for the soil was then matched with the reduction factor and the results were ranked in order of increasing Qu. Reduction factors were then grouped by Qu and applied to each bridge site and soil. These results, and comparison with the SRICOS Zmax calculation, show that less than half of the reduction-factor method values were the lowest estimate of scour; whereas, the Zmax method values were the lowest estimate for over half. A tiered approach to predicting pier and contraction scour was developed. There are four levels to this approach numbered in order of complexity, with the fourth level being a full SRICOS-EFA analysis. Levels 1 and 2 involve the reduction factors and Zmax calculation, and can be completed without EFA data. Level 3 requires some surrogate EFA data. Levels 3 and 4 require streamflow for input into SRICOS. Estimation techniques for both EFA surrogate data and streamflow data were developed.

Illinois↗

USGS2010

The New Albany shale in Illinois: Emerging play or prolific source

The New Albany shale (Upper Devonian) in the Illinois basin is the primary hydrocarbon source rock for the basins nearly 4 billion bbl of oil production to date. The gas play is well-established in Indiana and Western Kentucky. One in-situ oil producing well was reported in a multiply competed well in the New Albany at Johnsonville field in Wayne County, Illinois. The Illinois gas and oil wells at Russellville, in Lawrence County are closely associated with the 0.6% reflectance contour, which suggests a higher level of thermal maturity in this area. Today, only one field, Russellville in eastern Lawrence County has established commercial production in the Ness Albany in Illinois. Two wildcat wells with gas shows were drilled in recent years in southern Saline County, where the New Albany is relatively deeply buried and close to faults associated with the Fluorspar District.

Illinois↗

USGS2010

Distribution of Escherichia coli and Enterococci in water, sediments, and bank soils along North Shore Channel between Bridge Street and Wilson Avenue, Metropolitan Water Reclamation District of Greater Chicago

The Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) wished to know the distribution and potential sources of fecal indicator bacteria, E. coli and enterococci, in water, sediments, and upland soils along an upstream and downstream portion of the North Shore Channel (NSC) that is the receiving stream for the District’s North Side Water Reclamation Plant (NSWRP) outfall. Biweekly water and sediment samples were collected between August and October 2008 and included the following locations upstream of the outfall: Bridge Street (UPS-1), Oakton Street (UPS-2), the NSWRP outfall (OF), and downstream: Foster Avenue (DNS-1), and Wilson Avenue (DNS-2). E. coli and enterococci were consistently found in water and sediments at all sampling locations, with bacterial densities in water increasing below the NSWRP outfall; bacterial densities in sediment were more variable. On a relative measurement basis (i.e., 100 ml=100 g), both E. coli and enterococci densities were significantly higher in sediments than water. E. coli and enterococci were consistently recovered from bank soil along wooded, grassy, erosional, and depositional areas at two recreational parks, as well as other riparian areas along the river. Thus, soils along the river basin are likely sources of these bacteria to the NSC channel, introduced through runoff or other physical processes. Tributaries, such as the North Branch of the Chicago River (NBCR) that flow into NSC near Albany Ave, may provide a constant source of E. coli and enterococci to the NSC. Additionally, storm sewer outfalls may increase E. coli loadings to NSC during wet weather conditions. Our findings suggest that the abundance of nonpoint sources contributing to the overall fecal indicator bacteria (FIB) load in the NSC channel may complicate bacteria source determination and remediation efforts to protect the stream water quality.

Illinois↗

USGS2009

Soil geochemical signature of urbanization and industrialization – Chicago, Illinois, USA

The concentrations of 45 elements in ambient (not obviously disturbed) surface soils were determined for 57 sites distributed throughout the city of Chicago, Illinois in the upper Midwestern United States. These concentrations were compared to soils from 105 sites from a largely agricultural region within a 500-km radius surrounding the city and to soils collected from 90 sites across the state of Illinois. Although the bulk composition of the Chicago urban soils reflects largely natural sources, the soils are significantly enriched in many trace elements, apparently from anthropogenic sources. The median concentration of Pb in Chicago soils is 198 mg/kg, a 13-fold enrichment compared to regional concentrations. Zinc (median 235 mg/kg), Cu (59 mg/kg), and Ni (31 mg/kg) are also enriched from 2- to 4-fold in Chicago soils and all four elements show strong mutual correlations. These elevated concentrations are most likely related to vehicular and roadway sources and represent uneven distribution across the city as airborne material. Other airborne particulate material from a combination of fossil fuel combustion, waste incineration, and steel production may contribute to apparent elevated concentrations in Chicago soil of Fe (median 2.9%), Mo (5 mg/kg), V (82 mg/kg) and S (0.09%). Chicago soils are enriched from about 1.6- to 3-fold in these elements. Enrichments in P and Se may be caused by direct addition of phosphate fertilizer to parklands, lawns and gardens. The density of the sampling (1 site per 10 km 2 ) is inadequate to define the distribution of the observed enrichments within the city or to predict soil compositions for most of the areas between sample sites, but does provide a statistically significant signature of the history of urban and industrial activity within the city in contrast to the surrounding agricultural lands.

Illinois↗

USGS2009

Effect of detention basin release rates on flood flows: Application of a model to the Blackberry Creek Watershed in Kane County, Illinois

The effects of stormwater detention basins with specified release rates are examined on the watershed scale with a Hydrological Simulation Program - FORTRAN (HSPF) continuous-simulation model. Modeling procedures for specifying release rates from detention basins with orifice and weir discharge configurations are discussed in this report. To facilitate future detention modeling as a tool for watershed management, a chart relating watershed impervious area to detention volume is presented. The report also presents a case study of the Blackberry Creek watershed in Kane County, Ill., a rapidly urbanizing area seeking to avoid future flood damages from increased urbanization, to illustrate the effects of various detention basin release rates on flood peaks and volumes and flood frequencies. The case study compares flows simulated with a 1996 land-use HSPF model to those simulated with four different 2020 projected land-use HSPF model scenarios - no detention, and detention basins with release rates of 0.08, 0.10, and 0.12 cubic feet per second per acre (ft 3 /s-acre), respectively. Results of the simulations for 15 locations, which included the downstream ends of all tributaries and various locations along the main stem, showed that a release rate of 0.10 ft 3 /s-acre, in general, can maintain postdevelopment 100-year peak-flood discharge at a similar magnitude to that of 1996 land-use conditions. Although the release rate is designed to reduce the 100-year peak flow, reduction of the 2-year peak flow is also achieved for a smaller proportion of the peak. Results also showed that the 0.10 ft 3 /s-acre release rate was less effective in watersheds with relatively high percentages of preexisting (1996) development than in watersheds with less preexisting development.

Illinois↗

USGS2008

Measuring gravity currents in the Chicago River, Chicago, Illinois

Recent studies of the Chicago River have determined that gravity currents are responsible for persistent bidirectional flows that have been observed in the river. A gravity current is the flow of one fluid within another caused by a density difference between the fluids. These studies demonstrated how acoustic Doppler current profilers (ADCP) can be used to detect and characterize gravity currents in the field. In order to better understand the formation and evolution of these gravity currents, the U.S. Geological Survey (USGS) has installed ADCPs and other instruments to continuously measure gravity currents in the Chicago River and the North Branch Chicago River. These instruments include stage sensors, thermistor strings, and both upward-looking and horizontal ADCPs. Data loggers and computers installed at gaging stations along the river are used to collect data from these instruments and transmit them to USGS offices. ?? 2008 IEEE.

Illinois↗

USGS2008

The April 18, 2008 Illinois earthquake: an ANSS monitoring success

The largest-magnitude earthquake in the past 20 years struck near Mt. Carmel in southeastern Illinois on Friday morning, 18 April 2008 at 09:36:59 UTC (04:37 CDT). The Mw 5.2 earthquake was felt over an area that spanned Chicago and Atlanta, with about 40,000 reports submitted to the U.S. Geological Survey (USGS) “Did You Feel It?” system. There were at least six felt aftershocks greater than magnitude 3 and 20 aftershocks with magnitudes greater than 2 located by regional and national seismic networks. Portable instrumentation was deployed by researchers of the University of Memphis and Indiana University (the first portable station was installed at about 23:00 UTC on 18 April). The portable seismographs were deployed both to capture near-source, high-frequency ground motions for significant aftershocks and to better understand structure along the active fault. The previous similar-size earthquake within the Wabash Valley seismic zone (WVSZ) of southeastern Illinois and southwestern Indiana was a magnitude 5.0 in June 1987. The seismicity associated with the WVSZ is thought to occur in a complex horst and graben system of Precambrian igneous and metamorphic units at depths between 12 and 20 km. Paleoliquefaction evidence suggests several major shaking events have occurred within the past 12,000 years (Munson et al. 1997).

Illinois↗

USGS2008

Density currents in the Chicago River: Characterization, effects on water quality, and potential sources

Bidirectional flows in a river system can occur under stratified flow conditions and in addition to creating significant errors in discharge estimates, the upstream propagating currents are capable of transporting contaminants and affecting water quality. Detailed field observations of bidirectional flows were made in the Chicago River in Chicago, Illinois in the winter of 2005-06. Using multiple acoustic Doppler current profilers simultaneously with a water-quality profiler, the formation of upstream propagating density currents within the Chicago River both as an underflow and an overflow was observed on three occasions. Density differences driving the flow primarily arise from salinity differences between intersecting branches of the Chicago River, whereas water temperature is secondary in the creation of these currents. Deicing salts appear to be the primary source of salinity in the North Branch of the Chicago River, entering the waterway through direct runoff and effluent from a wastewater-treatment plant in a large metropolitan area primarily served by combined sewers. Water-quality assessments of the Chicago River may underestimate (or overestimate) the impairment of the river because standard water-quality monitoring practices do not account for density-driven underflows (or overflows). Chloride concentrations near the riverbed can significantly exceed concentrations at the river surface during underflows indicating that full-depth parameter profiles are necessary for accurate water-quality assessments in urban environments where application of deicing salt is common.

Illinois↗

USGS2007

Water level fluctuations in an urban pond: Climatic or anthropogenic impact?

In 1996, the Illinois State Geological Survey began an investigation of fluctuating water levels in a pond in Cary, Illinois. The cause of the fluctuations appeared to be ground water discharge into a storm sewer recently installed by the Illinois Department of Transportation. However, analysis of climatic data provided an equally likely explanation of the fluctuations. Distinguishing the effect of climatic variations from the effect of the storm sewer was hampered by the lack of antecedent ground water and surface water data. In similar settings, it is recommended that ground water and surface water data be collected prior to initiating any infrastructure improvements.

Illinois↗

USGS2007

Nitrate concentrations in Illinois rivers 1967 to 1974: Comparison among reporting agencies

Long term data on surface water quality can sometimes be assembled by combining data collected by different agencies at different times and assuming that between agency differences in data quality are insignificant. The objective of this paper was to assess the quality of riverine nitrate (NO3) concentrations in Illinois measured and reported by four agencies from 1967 to 1974 by comparing median values for similar sampling locations and periods. A total of 17 river reaches were identified for which two agencies reported NO3 concentrations during similar periods. Nonparametric comparison of median values and analysis of covariance with discharge as a covariant produced similar results. Nitrate concentrations reported by the U.S. Geological Survey (USGS) from 1967 to 1971 were not statistically (P > 0.05) different from values reported by the Illinois State Water Survey (ISWS) for two of three river reaches. Additionally, NO3 concentrations reported by USGS from 1972 to 1974 were not statistically different than concentrations reported by the Illinois Environmental Protection Agency (IEPA) for four of five river reaches. From 1969 to 1971, NO3 concentrations reported by the Illinois Department of Public Heath and the Illinois Environmental Protection Agency (IDPH/IEPA) were less than one-fourth the magnitude of values reported by ISWS. The median NO3 concentrations measured by the Central Illinois Public Service (CIPS) were significantly greater than those measured by USGS and IDPH/IEPA in the three comparable sampling locations. The use of NO 3 concentrations measured by CIPS and IDPH/IEPA prior to 1972 is not recommended.

Illinois↗