Geology topics

Padraic S. O’Shea

Publications and source records attributed to Padraic S. O’Shea.

13 recordsLinked to original sources

USGS2026

Floods of June 20–July 6, 2024, in the Big Sioux River, Rock River, Little Sioux River, Ocheyedan River, and Floyd River Basins, northwestern Iowa

Major flooding occurred on June 20–July 6, 2024, in northwestern Iowa affecting the Big Sioux, Rock, Little Sioux, Ocheyedan, and Floyd River Basins. Heavy rain fell in northwestern Iowa, southwestern Minnesota, and southeastern South Dakota on June 20–22, 2024. Parts of northwestern Iowa recorded 2–6 inches of rainfall and localized amounts exceeding 12 inches. A maximum peak-of-record streamflow of 175,000 cubic feet per second at the U.S. Geological Survey streamgage Big Sioux River at Akron, Iowa (06485500), was recorded on June 22, 2024, and had an annual exceedance probability range of 0.2–0.49 percent. High-water marks were measured at four locations along the Big Sioux River between U.S. Interstate 29 at Sioux City, Iowa, upstream to Iowa Highway 10 north of Hawarden, Iowa, a distance of 75.7 river miles. A maximum peak-of-record streamflow of 157,000 cubic feet per second at the U.S. Geological Survey streamgage Rock River near Rock Valley, Iowa (06483500), was recorded on June 22, 2024, and had an annual exceedance probability of less than 0.2 percent. High-water marks were measured at eight locations along the Rock River between County Road B30 east of Hudson, South Dakota, upstream to Iowa Highway 9 at Rock Rapids, Iowa, a distance of 39.3 river miles. A maximum peak-of-record streamflow of 63,000 cubic feet per second at the U.S. Geological Survey streamgage Little Sioux River at Correctionville, Iowa (06606600), was recorded on June 24, 2024, and had an annual exceedance probability range of 0.2–0.49 percent. High-water marks were measured at 11 locations along the Little Sioux River between Iowa Highway 31 west of Correctionville, Iowa, upstream to U.S. Highway 18 north of Spencer, Iowa, a distance of 134.8 river miles. A maximum streamflow of 24,500 cubic feet per second at the U.S. Geological Survey streamgage Ocheyedan River near Spencer, Iowa (06605000), was recorded on June 22, 2024, and had an annual exceedance probability range of 0.2–0.49 percent. High-water marks were measured at three locations along the Ocheyedan River between County Road M38 west of Spencer, Iowa, upstream to U.S. Highway 18 west of Everly, Iowa, a distance of 12.8 river miles. A maximum streamflow of 41,000 cubic feet per second at the U.S. Geological Survey streamgage Floyd River at Alton, Iowa (06600100), was recorded on June 22, 2024, and had an annual exceedance probability range of 1–1.99 percent. High-water marks were measured at six locations along the Floyd River between Iowa Highway 3 at Le Mars, Iowa, upstream to Iowa Highway 10 at Alton, Iowa, a distance of 27.5 river miles. The high-water marks were used to develop flood profiles for the Big Sioux, Rock, Little Sioux, Ocheyedan, and Floyd Rivers.

Iowa, Minnesota, South Dakota↗

USGS2026

Floods of June 2024 in northwestern Iowa

Following a heavy, multiday rainfall event that took place between June 20 and June 22, 2024, widespread flooding occurred in parts of northwestern Iowa. Ten U.S. Geological Survey (USGS) streamgages with periods of record ranging from 56 to 99 years in length experienced new peaks of record, three of which were more than double the previous peak-of-record: 06483500 (Rock River near Rock Valley, Iowa), 06605850 (Little Sioux River at Linn Grove, Iowa), and 06606600 (Little Sioux River at Correctionville, Iowa). A Presidential declaration of a major disaster for the State of Iowa was approved on June 24, 2024, and the cost of the flooding is estimated at over $310 million. The severity of this flooding prompted the USGS, in cooperation with the Iowa Department of Transportation, to summarize the meteorological and hydrological conditions preceding the flooding, compile estimates of the magnitude of peak flows resulting from the flooding, and update estimates of peak-flow frequency for selected USGS streamgages. Of the 33 streamgages analyzed, a peak streamflow occurred that corresponded to an annual exceedance probability of less than 4 percent at 13 streamgages, an annual exceedance probability of less than 1 percent at 6 streamgages, and an annual exceedance probability of less than 0.2 percent at 1 streamgage.

Iowa↗

USGS2026

Estimation of magnitude and frequency of floods for rural, unregulated streams in and near Virginia and West Virginia

Magnitude and frequency of annual peak streamflows were computed for 813 streamgages on rural, unregulated streams with annual peak streamflow data from 1791 through the 2021 water years in and near Virginia and West Virginia. The study was done in cooperation with the Federal Emergency Management Agency, the West Virginia Department of Transportation, and the Virginia Department of Transportation. Regression equations were developed for estimating flood frequency and magnitude. Twelve regions with homogeneous flood characteristics were identified. Generalized least squares regression equations relating logarithmic-transformed drainage area and peak streamflow were developed for the 0.5, 0.2, 0.1, 0.04, 0.02, 0.01, 0.005, and 0.002 annual exceedance probabilities (AEPs). Drainage area was the only significant variable for all equations. The range of drainage areas used to develop the equations differed for each region; the smallest drainage area in any region was 0.21 square miles (mi 2 ) and the largest drainage area in any region is 2,966 mi 2 . Pseudo coefficient of determination (pseudo- R 2 ) values for regression equations ranged from 0.481 to 0.995 for all regions and AEPs. Performance metrics and diagnostic plots indicated that equations for 11 of the 12 regions showed generally good performance, with pseudo- R 2 values ranging from 0.762 to 0.968 for the 0.01 AEP. The overall average change in at-site 0.01 AEP annual peak streamflows at individual streamgages was 0.5 percent compared to the most recent 2011 Virginia study and 2.3 percent compared to the most recent 2010 West Virginia study. Changes from the previous studies for estimates from regional equations for the 0.01 AEP, solved specifically for a 50 mi 2 basin, ranged from a 30 percent increase to a 45 percent decrease in areas where the previous regions overlapped with the current regions by 750 mi 2 or more. New regional skews were developed using Bayesian weighted least-squares/Bayesian generalized least-squares regression for two skew regions that included the study area. A constant regional skew of 0.50 was computed for streams in Virginia, West Virginia, and Maryland that drain to the Atlantic Ocean. A constant regional skew of 0.048 was computed for streams that drain to the Gulf of America, including streams in Kentucky and Tennessee, most of West Virginia, far southwestern Virginia, and part of western Maryland. About 12 percent of the 418 streamgages with 30 or more gaged peaks had statistically significant (p-value [significance level] less than or equal to 0.05) trends, with 40 of these exhibiting positive trends and 11 exhibiting negative trends. Streamgages with 30 percent or greater development were excluded from regression analyses. A regulation index was developed that accounted for storage and drainage area of dams and drainage area at the streamgage; a value of 0.0040 or more for the regulation index indicates regulated peak streamflow. Frequency analyses were done at 86 streamgages on regulated streams. Regression procedures developed in this study are applicable only to rural, unregulated streams within Virginia and West Virginia with drainage basins that (1) are within the range of drainage areas used to develop the equations for each region, (2) included less than 30 percent of developed area, and (3) had a regulation index less than 0.0040.

Kentucky, Maryland, North Carolina, Ohio, Pennsylv↗

USGS2025

Hydroclimatic and land-use factors affecting peak streamflow in Illinois, Iowa, Michigan, Minnesota, Missouri, Montana, North Dakota, South Dakota, and Wisconsin

Flood-frequency analysis provides the basis for flood risk estimates used by water-resource managers in land-use planning, and it informs the design of essential infrastructure such as bridges and culverts. Federal guidelines for flood-frequency analysis do not offer guidance on addressing changing climate and land-use conditions when estimating floods. However, failing to consider climatic and land-use changes that cause abrupt or gradual changes in flood regimes can result in a poor representation of the true flood risk. In response to concerns about changing flood regimes, the U.S. Geological Survey, in cooperation with nine State agencies (Illinois Department of Transportation, Iowa Department of Transportation, Michigan Department of Transportation, Minnesota Department of Transportation, Missouri Department of Transportation, Montana Department of Natural Resources and Conservation, North Dakota Department of Water Resources, South Dakota Department of Transportation, and Wisconsin Department of Transportation) began a study to examine variability and change in hydrology and climate and the effects of urbanization and tile drainage on flooding. The analyses of patterns and changes in hydrology and climate were reported in a multichapter Scientific Investigations Report, the findings of which are summarized in this U.S. Geological Survey Circular. Additional analyses documenting changes in seasonality of flooding and the effects of urbanization and tile drainage were completed and published as separate studies and are also summarized in this Circular. These studies provide extensive exploratory analysis of peak streamflow, daily streamflow, and climate data, setting the stage for advancements in flood-frequency analysis.

Illinois, Iowa, Michigan, Minnesota, Missouri, Mon↗

USGS2025

Assessing microplastics, per- and polyfluoroalkyl substances (PFAS), and other contaminants of global concern in wadable agricultural streams

Microplastics, per- and polyfluoroalkyl substances (PFAS), antibiotic resistance genes (ARGs), pharmaceuticals and personal care products (PPCPs), and pesticides may lead to unintended environmental contamination through many pathways in multiple matrices. This statewide, multi-matrix study of contaminants of global concern (CGCs) in agricultural streams across Iowa (United States) is the first to examine multiple CGCs in water, bed sediment, and fish to understand their occurrence in small streams located in regions of intense agriculture activity. Iowa plays a pivotal role in agriculture, with more than 85% of Iowa’s landscape devoted to agriculture making it an ideal location for determining the prevalence of CGCs to provide critical baseline exposure data. Fifteen sites were sampled across a range of predominant land uses (e.g., poultry, swine); all sites had detections of microplastics in all matrices. Concentrations of PFAS varied but were detected in water and sediment; all fish had detections of perfluorooctanesulfonate (PFOS), a type of PFAS. More than 50% of water and bed sediment samples had detections of ARGs. The most frequently detected PPCP was metformin. No sites had a cumulative exposure activity ratio greater than 1.0 for chemical exposures; 13 sites were above the 0.001 precautionary threshold. Toxicity quotients calculated using Aquatic Life Benchmarks were below the 0.1 moderate risk threshold for chemical exposures for all but one site. For fish, all sites exceeded the moderate and high-risk thresholds proposed for microplastic particles for food dilution (both chronic and acute exposures) and all sites exceeded the microplastic moderate threshold proposed for chronic tissue translocation, and two sites exceeded the threshold for acute tissue translocation.

Iowa↗

USGS2024

Peak streamflow trends in Iowa and their relation to changes in climate, water years 1921–2020

This study summarizes trends and change points for peak and daily streamflow in Iowa from water years 1921 through 2020. Nonstationarity in peak streamflow in Iowa can include monotonic trends, change points, and changes in seasonality. Spatial patterns of nonstationarity in peak streamflow, daily streamflow, and monthly climatic data (observed and modeled) were examined across four temporal periods. Upward trends in peak and daily streamflow were detected across central and eastern Iowa, from 1921 onward and were likely predominantly driven by increases in annual and seasonal precipitation during this time.

Iowa↗

USGS2024

Introduction and methods of analysis for peak streamflow trends and their relation to changes in climate in Illinois, Iowa, Michigan, Minnesota, Missouri, Montana, North Dakota, South Dakota, and Wisconsin

Flood-frequency analysis, also called peak-flow frequency or flood-flow frequency analysis, is essential to water resources management applications including critical structure design and floodplain mapping. Federal guidelines for doing flood-frequency analyses are presented in a U.S. Geological Survey Techniques and Methods Report known as Bulletin 17C. A basic assumption within Bulletin 17C is that for drainage basins without major hydrologic alterations, statistical properties of the distribution of annual peak streamflows (peak flows) are stationary; that is, the mean, variance, and skew are constant. The stationarity assumption has been widely accepted within the flood-frequency community; however, a better understanding of long-term climatic persistence and concerns about potential climate change and land-use change has caused a reexamination of the stationarity assumption. Flood-frequency analyses that do not incorporate observed trends and abrupt changes may result in a poor representation of the true flood risk. Bulletin 17C does not offer guidance for incorporating nonstationarities when estimating floods, and it describes a need for studies that incorporate changing climate or basin characteristics. In response to this need and a history of concern regarding nonstationarity peak flows in the region, this study was done by the U.S. Geological Survey, in cooperation with the Departments of Transportation of Illinois, Iowa, Michigan, Minnesota, Missouri, South Dakota, and Wisconsin; the Montana Department of Natural Resources and Conservation; and the North Dakota Department of Water Resources, to assess potential nonstationarity in peak flows in the north-central United States. This chapter summarizes the methods used to detect hydroclimatic changes in peak-flow data in the study region. A wide range of analyses and statistical approaches are applied to document the primary mechanisms controlling floods and characterize temporal changes in hydroclimatic variables and peak flow. Four periods were selected for analysis of peak flow, daily streamflow, and climate data. The periods are (1) a 100-year period, 1921–2020; (2) a 75-year period, 1946–2020; (3) a 50-year period, 1971–2020; and (4) a 30-year period, 1991–2020. The climate data consist of monthly time series estimates of temperature, precipitation, potential evapotranspiration, actual evapotranspiration, snowfall, soil moisture storage, snow water equivalent, and runoff on a 3.1-mile by 3.1-mile grid for the conterminous United States. Statistical and graphical analyses were used to investigate potential changes in hydrology and climate. The starting point for these analyses was the initial data analysis of peak flow described in Bulletin 17C, which includes plotting the peak flow and checking for autocorrelation, monotonic trends, and changes points. Analyses were added to examine additional features in the data. To examine potential causal drivers of changes, the climate data were analyzed graphically and statistically. Results are provided in a U.S. Geological Survey data release. The study limitations are documented for users of the results.

Iowa, Illinois, Michigan, Missouri, Minnesota, Mon↗

USGS2023

Estimating peak-flow quantiles for selected annual exceedance probabilities in Illinois

This report presents the methods, results, and applications of an updated flood-frequency study for the State of Illinois. This study, which uses data through September 2017, updates two previous studies that used data through 1999 and 2009, respectively. Flood-frequency estimates are used for a variety of land-use planning and infrastructure design purposes, including for the hydraulic design of bridges. The flood frequencies presented are the stream discharges (or quantiles) that are exceeded each year with a given probability, called the annual exceedance probability (AEP). Estimates are provided for eight AEPs: 0.5, 0.2, 0.1, 0.04, 0.02, 0.01, 0.005, and 0.002. The basic data used are the annual maximum discharges (peak flows) at streamgages in and near Illinois and the measurable physical properties (basin characteristics) of the basins upstream from those streamgages. The logarithms of the peak flow records at qualifying streamgages were fit to the Pearson Type 3 distribution using federally recommended methods, providing one of the two primary products of the study, which is the set of peak-flow quantiles at the streamgages and their uncertainties. The other primary product is sets of equations, determined by least-squares regression, that relate the peak-flow quantiles and the basin characteristics. There is one set of equations for each of Illinois’ seven hydrologic regions, and, for each region, one equation for each AEP. These regional equations allow the estimation of peak-flow quantiles at ungaged locations throughout the state and their uncertainties. A set of illustrative example applications is provided, and tables of all results at all study streamgages and regions are provided in associated data releases. The study results are also being made available in a web application, StreamStats.

Illinios↗

USGS2022

Floods of June 21–July 1, 2018, in the Floyd River and Little Sioux River Basins, northwestern Iowa

The Floyd River and Little Sioux River Basins in northwestern Iowa flooded on June 21–July 1, 2018, after sustained rainfall on June 14–27, 2018. Within the Floyd River Basin, rainfall totals from June 14 to 21 preceding flooding were 3.01 inches (in.) at Le Mars, 4.50 in. at Orange City, and 7.44 in. at Sheldon. Within the Little Sioux River Basin, rainfall amounts for the 2-week period from June 14 to 27 preceding flooding were 11.29 in. at Lake Park, 12.95 in. at Milford, 5.56 in. at Spencer, 7.71 in. at Sioux Rapids, and 6.13 in. at Cherokee. Flooding in the Floyd River Basin resulted in a recorded maximum peak discharge of 14,300 cubic feet per second (ft 3 /s; annual exceedance probability [AEP] estimate between 4 and 10 percent) at the U.S. Geological Survey (USGS) streamgage Floyd River at Alton, Iowa (06600100), and a recorded maximum peak discharge of 9,180 ft 3 /s (AEP estimate greater than 10 percent) at the USGS streamgage Floyd River at James, Iowa (06600500). Flooding in the Little Sioux River Basin resulted in a recorded maximum peak discharge of 16,300 ft 3 /s (AEP estimate between 4 and 10 percent) at the USGS streamgage Little Sioux River at Linn Grove, Iowa (06605850), and maximum peak discharges of 18,700 ft 3 /s (AEP estimate greater than 10 percent) and 20,000 ft 3 /s (AEP estimate greater than 10 percent) were recorded at the USGS streamgages Little Sioux River at Correctionville, Iowa (06606600), and Little Sioux River near Turin, Iowa (06607500), respectively. High-water mark elevations were surveyed at 19 locations along the Floyd River and 22 locations along the Little Sioux River to develop 2 flood profiles: a 52.5-mile profile along the Floyd River from State Highway 3 at Le Mars to U.S. Highway 18 at Sheldon that includes the USGS streamgage Floyd River at Alton and a 101-mile profile along the Little Sioux River from U.S. Highway 59 at Cherokee to U.S. Highway 18 north of Spencer that includes the USGS streamgage Little Sioux River at Linn Grove.

Iowa↗

USGS2021

Flood of June 30–July 1, 2018, in the Fourmile Creek Basin, near Ankeny, Iowa

Major flooding occurred June 30–July 1, 2018, in the Fourmile Creek Basin in central Iowa after thunderstorm activity over the region. The largest recorded 24-hour precipitation total at a National Oceanic and Atmospheric Administration weather station was 8.72 inches in Ankeny, Iowa, and 7.54 inches in Des Moines, Iowa. A maximum peak-of-record discharge of 10,000 cubic feet per second was recorded at U.S. Geological Survey streamgage 05485605, Fourmile Creek near Ankeny, Iowa, on July 1, 2018, with an annual exceedance probability of less than 0.2 percent. A maximum peak-of-record discharge of 12,000 cubic feet per second also was recorded at U.S. Geological Survey streamgage 05485640, Fourmile Creek at Des Moines, Iowa, on July 1, 2018, with an annual exceedance-probability range of 0.5–1 percent. High-water mark elevations were surveyed at 11 locations along Fourmile Creek between State Highway 163 in Pleasant Hill, Iowa, and U.S. Route 69 near Alleman, Iowa, a distance of 21.0 river miles. The high-water marks were used to develop a flood profile for Fourmile Creek.

Iowa↗

USGS2018

Stream-channel and watershed delineations and basin-characteristic measurements using lidar elevation data for small drainage basins within the Des Moines Lobe landform region in Iowa

Basin-characteristic measurements related to stream length, stream slope, stream density, and stream order have been identified as significant variables for estimation of flood, flow-duration, and low-flow discharges in Iowa. The placement of channel initiation points, however, has always been a matter of individual interpretation, leading to differences in stream definitions between analysts. This study investigated five different methods to define stream initiation using 3-meter light detection and ranging (lidar) digital elevation models (DEMs) data for 17 streamgages with drainage areas less than 50 square miles within the Des Moines Lobe landform region in north-central Iowa. Each DEM was hydrologically enforced and the five stream initiation methods were used to define channel initiation points and the downstream flow paths. The five different methods to define stream initiation were tested side-by-side for three watershed delineations: (1) the total drainage-area delineation, (2) an effective drainage-area delineation of basins based on a 2-percent annual exceedance probability (AEP) 12-hour rainfall, and (3) an effective drainage-area delineation based on a 20-percent AEP 12-hour rainfall. Generalized least squares regression analysis was used to develop a set of equations for sites in the Des Moines Lobe landform region for estimating discharges for ungaged stream sites with 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent AEPs. A total of 17 streamgages were included in the development of the regression equations. In addition, geographic information system software was used to measure 58 selected basin-characteristics for each streamgage. Results of the regression analyses of the 15 lidar datasets indicate that the datasets that produce regional regression equations (RREs) with the best overall predictive accuracy are the National Hydrographic Dataset, Iowa Department of Natural Resources, and profile curvature of 0.5 stream initiation methods combined with the 20-percent AEP 12-hour rainfall watershed delineation method. These RREs have a mean average standard error of prediction (SEP) for 4-, 2-, and 1-percent AEP discharges of 53.9 percent and a mean SEP for all eight AEPs of 55.5 percent. Compared to the RREs developed in this study using the basin characteristics from the U.S. Geological Survey StreamStats application, the lidar basin characteristics provide better overall predictive accuracy.

Iowa↗

USGS2018

Flood of August 24–25, 2016, Upper Iowa River and Turkey River, northeastern Iowa

Major flooding occurred August 24–25, 2016, in the Upper Iowa River Basin and Turkey River Basin in northeastern Iowa following severe thunderstorm activity over the region. About 8 inches of rain were recorded for the 24-hour period ending at 4 p.m., August 24, at Decorah, Iowa, and about 6 inches of rain were recorded for the 24-hour period ending at 7 a.m., August 24, at Cresco, Iowa, about 14 miles northwest of Spillville, Iowa. A maximum peak-of-record discharge of 38,000 cubic feet per second in the Upper Iowa River at streamgage 05388250 Upper Iowa River near Dorchester, Iowa, occurred on August 24, 2016, with an annual exceedance-probability range of 0.2–1 percent. High-water marks were measured at six locations along the Upper Iowa River between State Highway 26 near the mouth at the Mississippi River and State Highway 76 about 3.5 miles south of Dorchester, Iowa, a distance of 15 river miles. Along the profiled reach of the Turkey River, a maximum peak-of-record discharge of 15,300 cubic feet per second at streamgage 05411600 Turkey River at Spillville, Iowa, occurred on August 24, 2016, with an annual exceedance-probability range of 1–2 percent. A maximum peak discharge of 35,700 cubic feet per second occurred on August 25, 2016, along the profiled reach of the Turkey River at streamgage 05411850 Turkey River near Eldorado, Iowa, with an annual exceedance-probability range of 0.2–1 percent. High-water marks were measured at 11 locations along the Turkey River between County Road B64 in Elgin and 220th Street, located about 4.5 miles northwest of Spillville, Iowa, a distance of 58 river miles. The high-water marks were used to develop flood profiles for the Upper Iowa River and Turkey River.

Iowa↗

USGS2016

Estimation of peak discharge quantiles for selected annual exceedance probabilities in northeastern Illinois

This report provides two sets of equations for estimating peak discharge quantiles at annual exceedance probabilities (AEPs) of 0.50, 0.20, 0.10, 0.04, 0.02, 0.01, 0.005, and 0.002 (recurrence intervals of 2, 5, 10, 25, 50, 100, 200, and 500 years, respectively) for watersheds in Illinois based on annual maximum peak discharge data from 117 watersheds in and near northeastern Illinois. One set of equations was developed through a temporal analysis with a two-step least squares-quantile regression technique that measures the average effect of changes in the urbanization of the watersheds used in the study. The resulting equations can be used to adjust rural peak discharge quantiles for the effect of urbanization, and in this study the equations also were used to adjust the annual maximum peak discharges from the study watersheds to 2010 urbanization conditions. The other set of equations was developed by a spatial analysis. This analysis used generalized least-squares regression to fit the peak discharge quantiles computed from the urbanization-adjusted annual maximum peak discharges from the study watersheds to drainage-basin characteristics. The peak discharge quantiles were computed by using the Expected Moments Algorithm following the removal of potentially influential low floods defined by a multiple Grubbs-Beck test. To improve the quantile estimates, regional skew coefficients were obtained from a newly developed regional skew model in which the skew increases with the urbanized land use fraction. The skew coefficient values for each streamgage were then computed as the variance-weighted average of at-site and regional skew coefficients. The drainage-basin characteristics used as explanatory variables in the spatial analysis include drainage area, the fraction of developed land, the fraction of land with poorly drained soils or likely water, and the basin slope estimated as the ratio of the basin relief to basin perimeter. This report also provides the following: (1) examples to illustrate the use of the spatial and urbanization-adjustment equations for estimating peak discharge quantiles at ungaged sites and to improve flood-quantile estimates at and near a gaged site; (2) the urbanization-adjusted annual maximum peak discharges and peak discharge quantile estimates at streamgages from 181 watersheds including the 117 study watersheds and 64 additional watersheds in the study region that were originally considered for use in the study but later deemed to be redundant. The urbanization-adjustment equations, spatial regression equations, and peak discharge quantile estimates developed in this study will be made available in the web application StreamStats, which provides automated regression-equation solutions for user-selected stream locations. Figures and tables comparing the observed and urbanization-adjusted annual maximum peak discharge records by streamgage are provided at https://doi.org/10.3133/sir20165050 for download.

Illinois↗