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Research about Iowa

Source-linked reports with geographic coverage including Iowa.

At least 181 records · Page 10Linked to original sources
USGS2006

Bathymetric contour maps for lakes surveyed in Iowa in 2003

The U.S. Geological Survey, in cooperation with the Iowa Department of Natural Resources (IDNR), conducted bathymetric surveys on four lakes in Iowa during 2003 (Don Williams Lake, Easter Lake, Lake Macbride, and Lake Meyer). The purpose of the surveys is to provide the IDNR with information for the development of total maximum daily load (TMDL) limits, in particular, for estimating sediment load and deposition rates. The bathymetric surveys can provide a baseline for future work on sediment loads and deposition rates for these lakes. All lakes surveyed in 2003 are man-made lakes with fixed spillways. Bathymetric data were collected using boat-mounted, differential global positioning system (GPS) equipment, echo depth-sounding equipment, and computer software. Data were processed with commercial hydrographic software and exported into a geographic information system (GIS) for mapping and calculation of area and volume. Lake volume estimates ranged from 590,501,000 cubic feet (13,600 acre-feet) at Lake Macbride to 17,831,000 cubic feet (410 acre-feet) at Lake Meyer. Surface area estimates ranged from 38,118,000 square feet (875 acres) at Lake Macbride to 1,373,000 square feet (32 acres) at Lake Meyer.

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USGS2006

Bathymetric contour maps of lakes surveyed in Iowa in 2004

The U.S. Geological Survey, in cooperation with the Iowa Department of Natural Resources, conducted bathymetric surveys on six lakes in Iowa during 2004 (Lake Darling, Littlefield Lake, Lake Minnewashta, Nine Eagles Lake, Prairie Rose Lake, and Upper Gar Lake). The surveys were conducted to provide the Iowa Department of Natural Resources with information for the development of total maximum daily load limits, particularly for estimating sediment load and deposition rates. The bathymetric surveys can provide a baseline for future work on sediment loads and deposition rates for these lakes. Two of the lakes surveyed in 2004, Lake Minnewashta and Upper Gar Lake, are natural lakes. The other four lakes are manmade lakes with fixed spillways. Bathymetric data were collected using a boat-mounted, differential global positioning system, echo depth-sounding equipment, and computer software. Data were processed with commercial hydrographic software and exported into a geographic information system for mapping and calculating area and volume. Lake volume estimates ranged from 83,924,000 cubic feet (1,930 acre-feet) at Lake Darling to 5,967,000 cubic feet (140 acre-feet) at Upper Gar Lake. Surface area estimates ranged from 10,660,000 square feet (240 acres) at Lake Darling to 1,557,000 square feet (36 acres) at Upper Gar Lake.

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USGS2006

Hydrogeology and simulation of ground-water flow in the Silurian-Devonian aquifer system, Johnson County, Iowa

Bedrock of Silurian and Devonian age (termed the “Silurian-Devonian aquifer system”) is the primary source of ground water for Johnson County in east-central Iowa. Population growth within municipal and suburban areas of the county has resulted in increased amounts of water withdrawn from this aquifer and water-level declines in some areas. A 3-year study of the hydrogeology of the Silurian-Devonian aquifer system in Johnson County was undertaken to provide a quantitative assessment of ground water resources and to construct a ground-water flow model that can be used by local governmental agencies as a management tool. Johnson County is underlain by unconsolidated deposits of Quaternary age and Paleozoic-age bedrock units. The bulk of the Quaternary deposits consists of weathered and unweathered glacial till; however, shallow alluvium and buried sand and gravel deposits also are present. Six bedrock hydrogeologic units are present in Johnson County (oldest to youngest): Maquoketa confining unit, Silurian aquifer, Wapsipinicon Group (aquifer and confining unit), Cedar Valley aquifer, Upper Devonian shale confining unit, and Cherokee confining unit. Although separate aquifers and confining units are described, the Silurian- and Devonian-age units are considered as a single aquifer system. The top of the Silurian-Devonian aquifer system is considered as the top of the Cedar Valley aquifer, where present, and the base of the aquifer system is considered as the top of the Maquoketa confining unit. The hydraulic properties of the rocks that comprise the Silurian-Devonian aquifer system are highly variable as a result of the variable composition of the rocks and the presence of solution features in some of the carbonate-rock units. For the combined Silurian-Devonian aquifer system, specific capacity averages 2.1 gallons per minute per foot of drawdown, transmissivity averages about 580 feet squared per day, and hydraulic conductivity averages 8.3 feet per day. Recharge to the Silurian-Devonian aquifer system in Johnson County is predominantly from infiltration of precipitation to the bedrock. Discharge from the aquifer is primarily to municipal, industrial, and private-development wells. Reliable measurements of the amount of recharge to or discharge from the ground-water system in Johnson County, however, are not available. Altitude of the 1996 potentiometric surface ranged from more than 750 feet above the North American Vertical Datum of 1988 (NAVD88) in northern Johnson County to less than 575 feet above NAVD88 in the central part of the county. A large cone of depression within the potentiometric surface is present in the central part of the county, between Coralville and Iowa City. A large limestone quarry is located near the center of this cone of depression. Ground water generally flows from the northern and western parts of Johnson County either toward the cone of depression in the center of the county or south out of the county. Ground water also flows toward the Cedar River in the northeastern part of the county. A ground-water divide in the northeastern part of the county roughly approximates the surface-water divide between the Iowa River and Cedar River drainages. A numerical ground-water-flow model of the Silurian-Devonian aquifer system in Johnson County was used to test concepts of ground-water flow, to assess the need for additional data, and to evaluate the potential effects of anticipated increased ground-water development and drought. The 1-layer model was calibrated to average 1996 ground-water conditions, which were assumed to approximate steady-state flow conditions. The model also was used to simulate steady-state conditions for 2004, steady-state conditions using anticipated pumping rates for 2025, and potential future drought conditions. The simulated potentiometric surface generally replicated the potentiometric surface for 1996 and 2004 conditions. The calculated root mean squared error values for the 1996 and 2004 simulations were 13.6 and 18.6 feet, respectively. The mean absolute differences between measured and simulated water levels for the 1996 and 2004 simulations were about 11 and 14 feet, respectively. Total model-calculated inflow to the ground-water system for the 1996 simulation was 19.6 million gallons per day (Mgal/d), and the largest model-calculated inflow component was areal recharge (15.1 Mgal/d). Total model-calculated outflow from the ground-water system was 19.7 Mgal/d, and the largest outflow component was discharge to wells (10.5 Mgal/d). Model-calculated water-budget components for the 2004 simulation were similar to the 1996 components. Potential future steady-state conditions were simulated using anticipated 2025 pumping rates. Pumpage both for existing wells and for assumed new wells, based on anticipated population growth in the northern part of the county and for the nearby municipalities, was included in the model. Simulated 2025 pumpage was about 1.5 Mgal/d greater than simulated 2004 pumpage. Simulated steady-state ground-water levels, using anticipated 2025 pumping rates, were lower than 2004 simulated levels throughout the county, and simulated water-level declines ranged from less than 1 foot near the county boundaries to about 11 feet. Potential future drought conditions were simulated by assuming that recharge to the Silurian-Devonian aquifer system is reduced by a factor of 0.75 and that water-supply pumpage is increased by a factor of 1.25 over the anticipated 2025 pumping rates. Overall, simulated water levels for future drought conditions were greater than 5 feet lower than simulated 2004 conditions and were a maximum of about 30 feet lower in the northeastern part of the county. The greatest limitation to the model is the lack of measured or estimated water-budget components for comparison to simulated water-budget components. Because the model is only calibrated to measured water levels, and not to water-budget components, the model results are nonunique. Other model limitations include the relatively coarse grid scale, lack of detailed information on pumpage from the quarry and from private developments and domestic wells, and the lack of separate water-level data for the Silurian- and Devonian-age rocks.

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USGS2006

Occurrence of isoxaflutole, acetamide, and triazine herbicides and their degradation products in 10 Iowa rivers draining to the Mississippi and Missouri Rivers, 2004

During 2004, a study to document the occurrence of herbicides and herbicide degradation products was conducted for 10 major Iowa rivers draining to the Missouri and Mississippi Rivers. Seventy-five water-quality samples were collected to measure isoxaflutole, acetamide, and triazine herbicides and their herbicide degradation products. An analytical method to measure isoxaflutole and its degradation products, diketonitrile and benzoic acid, was developed by the U.S. Geological Survey Organic Geochemistry Research Laboratory in Lawrence, Kansas, using vacuum manifold solid-phase extraction and liquid chromatography/mass spectrometry/mass spectrometry and is described in this report. Isoxaflutole, a low application rate preemergence herbicide for control of annual broadleaf weeds, is used extensively in Iowa. Findings from the study documented in this report indicate that isoxaflutole was designed to degrade quickly to diketonitrile, which appears to be more stable, and then to benzoic acid. Of the 75 samples collected to measure isoxaflutole, there were four detections of isoxaflutole, 53 detections of diketonitrile, and 41 detections of benzoic acid. Also, results of acetamide and triazine water-quality samples correlate with past studies, which indicate that herbicide degradation products are detected more frequently and often at higher concentrations in surface water than their parent compounds. In addition to analysis of isoxaflutole and its degradation products, samples were analyzed by the USGS National Water-Quality Laboratory schedule 2001 for about 52 pesticides and their degradation products.

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USGS2006

Research plan and preliminary results: A field research site for emerging contaminants in Iowa

Research has recently documented the prevalence of a wide variety of pharmaceuticals and other emerging contaminants (ECs) in streams across the United States. Wastewater treatment plants (WWTPs) have been found to be an important source and collection point of ECs to streams as many ECs are incompletely removed during treatment. To investigate the complex in-stream processes (e.g., dilution, sorption, degradation, dispersion, etc.) that can affect ECs following their input from a WWTP and determining if such input is having an effect on the aquatic ecosystem requires the integration of multi-disciplinary efforts at a carefully selected field site. Preliminary work has identified an 8-km reach of Fourmile Creek in central Iowa as an ideal research site to investigate such important research questions pertaining to ECs. Unique aspects of Fourmile Creek included: (1) it single source effluent-dominated stream, (2) background data document the input of a wide variety of ECs from WWTP discharge, (3) small basin size, (4) relatively simple flow system, (5) background data suggest that undefined processes are taking place decreasing the level of select ECs during stream transport, (6) the WWTP uses a treatment technology (activated sludge) typical of many towns in Iowa and the United States (7) a hydrogeologic setting of a low-gradient, small stream (average discharge less than 1.41 m³/s) in glacial drift is typical of many areas in Iowa and across the Midwest, and (8) the existence of a low-head clam approximately 2 km upstream of the WWTP outfall allowing more accurate "above WWTP" and "below WWTP" comparisons in aquatic ecosystems. Furthermore, the WWTP is scheduled to close by 2011 providing a unique opportunity to determine how stream hydrology, water chemistry and aquatic biota react to the removal of the primary source of flow and ECs in this system. This will allow a novel "before" and "after" assessment not previously available in EC research. Research to date at the site has included installation of a streamflow gauging station, dye-tracing tests (to determine water travel times), Lagrangian water-quality sampling at two flow/water temperature regimes, and sampling for ECs in bed sediment. Selected fish have been collected for analysis and identification. In addition, basic fish community and fish health assessment for different seasons and spawning conditions are being analyzed. The research "framework" is unique at Fourmile Creek for investigating the important question of how ECs are transported through the environment and if the presence of such compounds is having a deleterious effect on aquatic ecosystems.

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USGS2005

Contribution of base flow to nonpoint source pollution loads in an agricultural watershed

Nonpoint source pollution of surface water from overland flow, drainage tiles, and ground water discharge is a major cause of water quality impairment in Iowa. Nonpoint source pollution from base flow ground water was estimated in the Walnut Creek watershed by measuring chemical loads of atrazine, nitrate, chloride, and sulfate at 18 tributary creeks and 19 tiles. Loads were measured during a stable base flow period at creeks and tiles that discharged into Walnut Creek between two stream gauges. Chemical concentrations of atrazine (< 0.1−12 μg/L), nitrate (0.1 to 15 mg/L, and chloride (1.5 to 26 mg/L) in water were similar for creek and tile samples. Water draining predominantly agricultural row crop areas had much higher concentrations than water draining restored prairie areas. Three methods were used to estimate base flow discharge in the watershed: (1) Darcy flux; (2) watershed discharge budget; and (3) discharge-drainage area; each yielded similar results (31.2 L/s to 62.3 L/s). Base flow loads to the main channel were estimated by subtracting the loads from the upstream gauge; creeks and tiles, from the total load measured at the downstream gauge station. Base flow concentration for atrazine ranged from 0.15 to 0.29 μg/L and sulfate concentration ranged from 32 to 64 mg/L, whereas concentrations for nitrate and chloride were negative (−1 to −4 mg/L). Calculated base flow concentrations of atrazine and sulfate appeared to be reasonable estimates, but negative concentrations of nitrate and chloride imply either loss of chemical mass in the stream from upstream to downstream sampling points or measurement error. Load data suggest little contribution from base flow pollutants to Walnut Creek water quality, with most of the pollutant load derived from major tributary creeks. Results from this study have implication for determining total maximum daily loads in agricultural watersheds where contributions from point sources (creeks and tiles) can be used to estimate loads from nonpoint source ground water inputs.

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USGS2005

Degradates provide insight to spatial and temporal trends of herbicides in ground water

Since 1995, a network of municipal wells in Iowa, representing all major aquifer types (alluvial, bedrock/karst region, glacial drift, bedrock/nonkarst region), has been repeatedly sampled for a broad suite of herbicide compounds yielding one of the most comprehensive statewide databases of such compounds currently available in the United States. This dataset is ideal for documenting the insight that herbicide degradates provide to the spatial and temporal distribution of herbicides in ground water. During 2001, 86 municipal wells in Iowa were sampled and analyzed for 21 herbicide parent compounds and 24 herbicide degradates. The frequency of detection increased from 17% when only herbicide parent compounds were considered to 53% when both herbicide parents and degradates were considered. Thus, the transport of herbicide compounds to ground water is substantially underestimated when herbicide degradates are not considered. A significant difference in the results among the major aquifer types was apparent only when both herbicide parent compounds and their degradates were considered. In addition, including herbicide degradates greatly improved the statistical relation to the age of the water being sampled. When herbicide parent compounds are considered, only 40% of the wells lacking a herbicide detection could be explained by the age of the water predating herbicide use. However, when herbicide degradates were also considered, 80% of the ground water samples lacking a detection could be explained by the age of the water predating herbicide use. Finally, a temporal pattern in alachlor concentrations in ground water could only be identified when alachlor degradates were considered.

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USGS2005

Observed and simulated movement of bank-storage water

Detailed hydrologic and water-chemistry data were collected that document the movement of bank-storage water during March 7-April 17, 1990, in an alluvial aquifer adjacent to the Cedar River, Iowa. Hydrologic data included 745 daily ground-water-level measurements from 27 observation wells. Water-chemistry data indicate that bank-storage water had smaller specific conductance and larger concentration of atrazine than ambient ground water. To quantify the movement of the bank-storage water, a two-dimensional ground-water flow model was constructed, and the resulting calibrated model accurately simulated observed conditions. Analysis of water chemistry and model results indicate that a 2-meter rise in the river stage caused bank-storage water to move horizontally at least 30 meters into the aquifer and vertically about 4 meters below the river bottom, whereas the remaining 30 percent moved laterally through the riverbank. The model also showed that bank storage caused the ground-water flux to the river to increase by a factor of five during the first three weeks of base flow after runoff and that it required about five weeks for bank-storage water to discharge from the alluvial aquifer after the peak river stage. These results quantitatively demonstrate the importance of bank storage as a source of recharge to the alluvial aquifer and as a source of water to the river during early base-flow conditions.

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USGS2005

Occurrence of selected herbicides and herbicide degradation products in Iowa's Ground Water, 1995

Herbicide compounds were prevalent in ground water across Iowa, being detected in 70% of the 106 municipal wells sampled during the summer of 1995. Herbicide degradation products were three of the four most frequently detected compounds for this study. The degradation product alachlor ethanesulfonic acid was the most frequently detected compound (65.1%), followed by atrazine (40.6%), and the degradation products deethylatrazine (34.9%), and cyanazine amide (19.8%). The corn herbicide acetochlor, first registered for widespread use in the United States in March 1994, was detected in a single water sample. No reported herbicide compound concentrations for this study exceeded currem U.S. Environmental Protection Agency's maximum contaminant levels or health advisory levels for drinking water, although the herbicide degradation products examined have yet to have such levels established. The occurrence of herbicide compounds had a significant, inverse relation to well depth and a significant, positive relation to dissolved-oxygen concentration. It is felt that both well depth and dissolved oxygen are acting as rough surrogates to ground-water age, with younger ground water being more likely to contain herbicide compounds. The occurrence of herbicide compounds was substantially different among the major aquifer types across Iowa, being detected in 82.5% of the alluvial, 81.8% of the bedrock/ karst region, 40.0% of the glacial-drift, and 25.0% of the bedrock/nonkarst region aquifers. The observed distribution was partially attributed to variations in general ground-water age among these aquifer types. A significant, inverse relation was determined between total herbicide compound concentrations in ground water and the average soil slope within a 2-km radius of sampled wells. Steeper soil slopes may increase the likelihood of surface runoff occurring rather than ground-water infiltration&ndash;decreasing the transport of herbicide compounds to ground water. As expected, a significant positive relation was determined between intensity of herbicide use and herbicide concentrations in ground water.

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USGS2005

Estimation of streamflow, base flow, and nitrate-nitrogen loads in Iowa using multiple linear regression models

Nineteen variables, including precipitation, soils and geology, land use, and basin morphologic characteristics, were evaluated to develop Iowa regression models to predict total streamflow (Q), base flow (Qb), storm flow (Qs) and base flow percentage (%Qb) in gauged and ungauged watersheds in the state. Discharge records from a set of 33 watersheds across the state for the 1980 to 2000 period were separated into Qb and Qs. Multiple linear regression found that 75.5 percent of long term average Q was explained by rainfall, sand content, and row crop percentage variables, whereas 88.5 percent of Qb was explained by these three variables plus permeability and floodplain area variables. Qs was explained by average rainfall and %Qb was a function of row crop percentage, permeability, and basin slope variables. Regional regression models developed for long term average Q and Qb were adapted to annual rainfall and showed good correlation between measured and predicted values. Combining the regression model for Q with an estimate of mean annual nitrate concentration, a map of potential nitrate loads in the state was produced. Results from this study have important implications for understanding geomorphic and land use controls on streamflow and base flow in Iowa watersheds and similar agriculture dominated watersheds in the glaciated Midwest.

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USGS2005

Iowa magnetic and gravity maps and data: A web site for distribution of data

Magnetic anomalies are due to variations in the Earth's magnetic field caused by the uneven distribution of magnetic minerals (primarily magnetite) in the rocks that make up the upper part of the Earth's crust. The features and patterns of the magnetic anomalies can be used to delineate details of subsurface geology, including the locations of buried faults and magnetite-bearing rocks and the depth to the base of sedimentary basins. This information is valuable for mineral exploration, geologic mapping, and environmental studies. The Iowa magnetic map is constructed from grids that combine information collected in nine separate magnetic surveys conducted between 1953 and 1972. The data from these surveys are of varying quality. The design and specifications (terrain clearance, sampling rates, line spacing, and reduction procedures) varied from survey to survey depending on the purpose of the project and the technology of that time. Every attempt was made to acquire the data in digital form. All survey grids have been continued to 305 m (1,000 ft) above ground and merged together to form the State compilation.

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USGS2005

Water resources data, Iowa water year 2004, volume 1: surface water and precipitation

This volume of the annual hydrologic data report of Iowa is one of a series of annual reports that document hydrologic data gathered from the U.S. Geological Survey.s surface- and ground-water data-collection networks in each State, Puerto Rico, and the Trust Territories. These records of streamflow, ground-water levels, and quality of water provide the hydrologic information needed by local, State, and Federal agencies, and the private sector for developing and managing our Nation.s land and water resources. This report is the culmination of a concerted effort by dedicated personnel of the U.S. Geological Survey who collected, compiled, analyzed, verified, and organized the data, and who typed, edited, and assembled the report. The authors had primary responsibility for assuring that the information contained herein is accurate, complete, and adheres to Geological Survey policy and established guidelines.

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USGS2005

Water resources data, Iowa, water year 2005

This volume of the annual hydrologic data report of Iowa is one of a series of annual reports that document hydrologic data gathered from the U.S. Geological Survey&rsquo;s surface- and ground-water data-collection networks in each State, Puerto Rico, and the Trust Territories. These records of streamflow, ground-water levels, and quality of water provide the hydrologic information needed by local, State, and Federal agencies, and the public for developing and managing our Nation&rsquo;s land and water resources. This report is the culmination of a concerted effort by dedicated personnel of the U.S. Geological Survey who collected, compiled, analyzed, verified, and organized the data, and who typed, edited, and assembled the report. The authors had primary responsibility for assuring that the information contained herein is accurate, complete, and adheres to U. S. Geological Survey policy and established guidelines.

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USGS2004

Urban contribution of pharmaceuticals and other organic wastewater contaminants to streams during differing flow conditions

During 2001, 76 water samples were collected upstream and downstream of select towns and cities in Iowa during high-, normal- and low-flow conditions to determine the contribution of urban centers to concentrations of pharmaceuticals and other organic wastewater contaminants (OWCs) in streams under varying flow conditions. The towns ranged in population from approximately 2000 to 200 000. Overall, one or more OWCs were detected in 98.7% of the samples collected, with 62 of the 105 compounds being found. The most frequently detected compounds were metolachlor (pesticide), cholesterol (plant and animal sterol), caffeine (stimulant), &beta;-sitosterol (plant sterol) and 1,7-dimethylxanthine (caffeine degradate). The number of OWCs detected decreased as streamflow increased from low- (51 compounds detected) to normal- (28) to high-flow (24) conditions. Antibiotics and other prescription drugs were only frequently detected during low-flow conditions. During low-flow conditions, 15 compounds (out of the 23) and ten compound groups (out of 11) detected in more than 10% of the streams sampled had significantly greater concentrations in samples collected downstream than in those collected upstream of the urban centers. Conversely, no significant differences in the concentrations were found during high-flow conditions. Thus, the urban contribution of OWCs to streams became progressively muted as streamflow increased.

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USGS2004

Quality of ground water for selected municipal water supplies in Iowa, 1997–2002 water years

The Iowa ground-water-quality monitoring program has been conducted cooperatively since 1982 by the Iowa Department of Natural Resources, Iowa Geological Survey; the University of Iowa Hygienic Laboratory; and the U.S. Geological Survey. The original objectives of the program were to provide baseline ground-water-quality data throughout the State for the major aquifers and to address any new areas of water-quality concern. Since the program began, the emphasis and objectives of the program have changed several times. As of 1992, greater emphasis has been placed on determining trends in ground-water quality and correlating water quality with possible contributing factors such as location, land use, aquifer, aquifer depth, and precipitation. From 1997 through 2002, a total of 471 samples of untreated water have been collected from 154 municipal wells throughout Iowa. The samples, collected from six different aquifers, consisted of 192 alluvial aquifer samples (36 wells), 79 Pleistocene aquifer samples (16 wells), 52 Cretaceous aquifer samples (35 wells), 48 Carboniferous aquifer samples (30 wells), 54 Silurian-Devonian aquifer samples (19 wells), and 46 Cambrian-Ordovician aquifer samples (18 wells). Some samples had concentrations greater than or equal to the respective Maximum Contaminant Levels for drinking water established by the U.S. Environmental Protection Agency. Of 471 samples analyzed, 19 samples had concentrations greater than or equal to the Maximum Contaminant Level for sulfate; 31 samples had concentrations greater than or equal to the Maximum Contaminant Level for nitrite plus nitrate; 257 samples had concentrations greater than or equal to the Secondary Maximum Contaminant Level for iron; and 249 samples had concentrations greater than or equal to the Secondary Maximum Contaminant Level for manganese. Of the 443 samples analyzed for pesticides, 87 samples had concentrations greater than or equal to the respective minimum reporting levels for the parent compounds, 30 samples had concentrations greater than or equal to the respective minimum reporting levels for pesticide metabolites, and 26 samples had detectable concentrations (censored values) less than the minimum reporting levels. Concentrations of alachlor, atrazine, cyanazine, and metolachlor accounted for about 90 percent of the samples equal to or exceeding the respective minimum reporting levels for pesticides. No samples had pesticide concentrations greater than the respective Maximum Contaminant or Health Advisory Levels. The compact disc included with this report has information about water-quality properties and concentrations of dissolved solids, major ions, nutrients, trace elements, radionuclides, total organic carbon, pesticides, and synthetic organic compounds for water years 1997 through 2002.

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USGS2004

Flood of June 4, 2002, in the Indian Creek Basin, Linn County, Iowa

Severe flooding occurred on June 4, 2002, in the Indian Creek Basin in Linn County, Iowa, following thunderstorm activity over east-central Iowa. The rain gage at Cedar Rapids, Iowa, recorded a 24-hour rainfall of 4.76 inches at 6:00 p.m. on June 4th. Radar indications estimated as much as 6 inches of rain fell in the headwaters of the Indian Creek Basin. Peak discharges on Indian Creek of 12,500 cubic feet per second at County Home Road north of Marion, Iowa, and 24,300 cubic feet per second at East Post Road in southeast Cedar Rapids, were determined for the flood. The recurrence interval for these peak discharges both exceed the theoretical 500-year flood as computed using flood-estimation equations developed by the U.S. Geological Survey. Information about the basin and flood history, the 2002 thunderstorms and associated flooding, and a profile of high-water marks are presented for selected reaches along Indian and Dry Creeks.

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USGS2004

Flood of June 4-5, 2002, in the Maquoketa River Basin, east-central Iowa

Severe flooding occurred on June 4-5, 2002, in the Maquoketa River Basin in Delaware, Dubuque, Jackson, and Jones Counties, following thunderstorm activity over east-central Iowa. The rain gage at Cascade, Iowa, recorded a 14-hour rainfall of 6.0 inches at noon on June 4. Radar indications estimated as much as 8 to 10 inches of rain fell in the upper-middle part of the Maquoketa River Basin. Peak discharges on the Maquoketa River at Monticello of 47,500 cubic feet per second (recurrence interval estimated to be greater than 500 years as computed using flood-estimation equations developed by the U.S. Geological Survey), and at the Maquoketa River near Maquoketa streamflow-gaging station of 47,900 cubic feet per second (recurrence interval about 50 years), were determined for the flood. The peak discharge of the 2002 flood is nearly equal that of the 1944 flood (48,000 cubic feet per second), the largest flood on record in the Maquoketa River Basin. The 2002 flood is the largest known flood in the North Fork Maquoketa River Basin. A peak discharge of 22,600 cubic feet per second (recurrence interval about 110 years) was determined for the flood at the North Fork Maquoketa River near Fulton gaging station. Information about the basin and flood history, the 2002 thunderstorms and associated flooding, and a profile of high-water marks are presented for selected reaches along the Maquoketa and North Fork Maquoketa Rivers.

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