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Source-linked reports with geographic coverage including Iowa.

At least 199 records · Page 11Linked to original sources
USGS2004

Riverbed elevations and water quality of the Missouri River at Sioux City, Iowa, 2002-03

The U.S. Geological Survey, in cooperation with the City of Sioux City, Iowa, conducted an investigation of the Missouri River, during 2002-2003, to assess changes in riverbed elevations from its confluence with the Big Sioux River, downstream to the area of the Sioux City municipal well field. Water-quality samples also were collected across the Missouri River to provide additional information on the differences between the water quality of the Missouri River and Big Sioux River in the well field area. The water supply at Sioux City, Iowa, is withdrawn from fourteen vertical wells and one horizontal collector well. Twelve vertical wells and the collector well are completed in the alluvial sand and gravel aquifer adjacent to the Missouri River at Sioux City. The well field is located on the left bank (looking downstream) of the Missouri River about 0.5 mile upstream from USGS streamflow gage 06486000, and approximately 5,000 feet downstream from the confluence with the Big Sioux River. The Missouri River, adjacent to the Sioux City alluvial well field, consists of the combined streamflows from the Missouri and the Big Sioux Rivers. The streamflows do not appear to be well mixed downstream from the confluence, and the streamflow directly adjacent to the well field could be predominately from the Big Sioux River. The U.S. Geological Survey measures streamflow on the Missouri River at Sioux City, Iowa (USGS streamflow gage 06486000). The riverbed of the Missouri River at Sioux City consists of a sequence of sands and gravels. The surface of the riverbed is undulatory, with continuously migrating riverbed forms, 5 to 8 feet in relief, of sand and gravel. Measurements of riverbed elevations from October 1, 2002, to September 30, 2003, showed an annual change of as much as 8 feet with the majority of the riverbed change closer to 5 feet. The largest change occurred near a wing dike on the Nebraska side of the Missouri River. On the Iowa side, the annual change was close to 5 feet. The results showed that channel fill occurred in the winter months and scour occurred during the summer months. Results of analyses of water samples collected at five locations across the Missouri River, near the municipal well field, were similar for most samples. Higher values of specific conductance and turbidity were recorded on the Iowa side of the Missouri River, the side from which the Big Sioux River enters upstream. Higher concentrations of chloride, ammonia nitrogen, nitrate nitrogen, and atrazine also were detected on the Iowa side of the Missouri River. Based on these results, there does not appear to be complete mixing of water from the Missouri and Big Sioux Rivers near the municipal well field.

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USGS2004

Simulation of ground-water flow in the Cedar River alluvial aquifer flow system, Cedar Rapids, Iowa

The Cedar River alluvial aquifer is the primary source of municipal water in the Cedar Rapids, Iowa, area. Since 1992, the U.S. Geological Survey, in cooperation with the City of Cedar Rapids, has investigated the hydrogeology and water quality of the Cedar River alluvial aquifer. This report describes a detailed analysis of the ground-water flow system in the alluvial aquifer, particularly near well field areas. The ground-water flow system in the Cedar Rapids area consists of two main components, the unconsolidated Quaternary deposits and the underlying carbonate bedrock that has a variable fracture density. Quaternary deposits consist of eolian sand, loess, alluvium, and glacial till. Devonian and Silurian bedrock aquifers overlie the Maquoketa Shale (Formation) of Ordovician age, a regional confining unit. Ground-water and surface-water data were collected during the study to better define the hydrogeology of the Cedar River alluvial aquifer and Devonian and Silurian aquifers. Stream stage and discharge, ground-water levels, and estimates of aquifer hydraulic properties were used to develop a conceptual ground-water flow model and to construct and calibrate a model of the flow system. This model was used to quantify the movement of water between the various components of the aluvial aquifer flow system and provide an improved understanding of the hydrology of the alluvial aquifer. Ground-water flow was simulated for the Cedar River alluvial aquifer and the Devonian and Silurian aquifers using the three-dimensional finite-difference ground-water flow model MODFLOW. The model was discretized into 223 rows and 354 columns of cells. Areal cell sizes range from about 50 feet on a side near the Cedar River and the Cedar Rapids municipal wells to 1,500 feet on a side near the model boundaries and farthest away from the Cedar Rapids municipal well fields. The model is separated into five layers to account for the various hydrogeologic units in the model area. Model results indicate that the primary sources of inflow to the modeled area are infiltration from the Cedar River (53.0 percent) and regional flow in the glacial and bedrock materials (34.1 percent). The primary sources of outflow from the modeled area are discharge to the Cedar River (45.4 percent) and pumpage (44.8 percent). Current steady-state pumping rates have increased the flow of water from the Cedar River to the alluvial aquifer by 43.8 cubic feet per second. Steady-state and transient hypothetical pumpage scenarios were used to show the relation between changes in pumpage and changes in infiltration of water from the Cedar River. Results indicate that more than 99 percent of the water discharging from municipal wells infiltrates from the Cedar River, that the time required for induced river recharge to equilibrate with municipal pumpage may be 150 days or more, and that ground-water availability in the Cedar Rapids area will not be significantly affected by doubling current pumpage as long as there is sufficient flow in the Cedar River to provide recharge.

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USGS2004

Water resources data, Iowa, water year 2003--Volume 1. Surface water and precipitation

Water resources data for Iowa for the 2003 water year consists of records of stage, discharge, and water quality of streams; stage, and/or contents of lakes and reservoirs; ground-water levels and water quality of ground-water wells. This report volume contains discharge records for 134 gaging stations; stage or contents for 9 lakes and reservoirs and 3 streams; water quality for 4 stream-gaging stations; sediment records for 11 stream-gaging stations; and precipitation record for 7 precipitation stations. Also included are data for 90 crest-stage partial-record stations.

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USGS2003

Surface water qualit: Revisiting nitrate concentrations in the Des Moines River: 1945 and 1976-2001

Recent compilations of historical and contemporary riverine nitrate (NO 3 ) concentrations indicate that concentrations in many rivers in the north-central USA increased during the second half of the 20th century. The Des Moines River near Des Moines, Iowa, however, was reported to have had similar NO 3 concentrations in 1945 and the 1980s, in spite of substantially greater N input to the watershed during the latter period. The objective of this study was to reconsider the comparison of historical and contemporary NO 3 concentrations in the Des Moines River near Des Moines in light of the following: (i) possible errors in the historical data used, (ii) variations in methods of sample collection, (iii) variations in location of sampling, and (iv) additional data collected since 1990. We discovered that an earlier study had compared the flow-weighted average concentration in 1945 to arithmetic annual average concentrations in the 1980s. The intertemporal comparison also appeared to be influenced by differences in sample collection methods and locations used at different times. Depending on the model used and the estimated effects of composite sample collection, the 1945 arithmetic average NO 3 concentration was between 44 and 57% of the expected mean value at a similar water yield during 1976–2001. The flow-weighted average NO 3 concentration for 1945 was between 54 and 73% of the expected mean value at a similar water yield during 1976–2001. The difference between NO 3 concentrations in 1945 and the contemporary period are larger than previously reported for the Des Moines River.

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USGS2003

Short-term bird response to harvesting switchgrass for biomass in Iowa

The Conservation Reserve Program (CRP) provides habitat for grassland birds, but as contracts expire, some CRP fields might be returned to rowcrop production. One alternative to returning CRP fields to rowcrops is to produce switchgrass ( Panicum virgatum ) for use as a biomass fuel. Because the biomass is harvested during the fall and winter, breeding birds would not be directly affected by mowing the fields bur might be influenced by changes in vegetation structure resulting from the harvest. We evaluated bird abundances and nest success in totally harvested, partially harvested (alternating cut and uncut strips), and nonharvested CRP switchgrass fields in southern Iowa, USA, in 1999 and 2000. Species richness did not differ among harvest treatments. Abundances of most species (16 of 18) were not affected by the harvesting of switchgrass fields, and strip width did not affect bird numbers in strip-harvested fields. Grasshopper sparrows ( Ammodramus savannarum ) were more abundant in harvested portions of fields, and more sedge wrens ( Cistothorus platensis ) were recorded in nonharvested areas. The residual vegetation in nonharvested areas provided nest cover for species that begin nesting early in the season (e.g., northern harrier [Circus cyaneus] and ring-necked pheasant [ Phasianus colchicus ]). Nest success rates of grasshopper sparrows and common yellowthroats ( Geothlypis trichas ) were similar to those reported by other studies in switchgrass fields and might be sufficient to maintain stable populations. In general, switchgrass biomass fields create breeding habitat for some grassland birds, and a mixture of harvested and nonharvested fields would be more beneficial to grassland birds than totally harvesting or partially harvesting all switchgrass fields.

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USGS2003

Water resources data, Iowa, water year 2002--Volume 1. surface water—Mississippi River Basin

Water resources data for Iowa for the 2002 water year consists of records of stage, discharge, and water quality of streams; stage, and/or contents of lakes and reservoirs; ground water levels and water quality of ground-water wells. This report volume contains discharge records for 95 gaging stations; stage or contents for 6 lakes and reservoirs and 7 streams; water quality for 1 stream-gaging station; sediment records for 10 stream-gaging stations; and precipitation record for 7 precipitation stations. Also included are data for 58 crest-stage partial record stations.

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USGS2003

Water resources data, Iowa, water year 2002--Volume 2. surface water—Missouri River Basin, and ground water

Water resources data for Iowa for the 2002 water year consists of records of stage, discharge, and water quality of streams; stage, and/or contents of lakes and reservoirs; ground water levels and water quality of ground-water wells. This report volume contains discharge records for 31 gaging stations; stage or contents for 3 lakes; water quality for 1 stream-gaging station, and sediment records for 2 stream-gaging stations. Also included are data for 33 crest-stage partial record stations and ground-water levels for 157 wells.

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USGS2003

Simulation of ground-water flow in the Cedar River alluvium, northwest Black Hawk County and southwest Bremer County, Iowa

Flooding and high ground-water levels after large or frequent rainstorms have occurred in an area of about 30 square miles along the eastern bank of the Cedar River from Cedar Falls in northwest Black Hawk County to Janesville in southwest Bremer County, Iowa. The U.S. Geological Survey, in cooperation with Black Hawk County, conducted a hydrologic study of the Cedar River alluvium in the northwest Black Hawk and southwest Bremer Counties, to improve understanding of the ground-water flow system and evaluate the effects of hypothetical variations in recharge and discharge conditions. A steady-state ground-water flow model was constructed for the area using November 2001 hydrologic conditions. The model was discretized into an 83-row by 47-column grid of cells measuring approximately 500 feet by 500 feet. Two model layers, one for the alluvium and one for the underlying bedrock units, were used to represent flow in the area. Precipitation during 2001 was similar to historical normals. Precipitation during 1999, especially during the summer when flooding occurred, was well above the historical normals. Borings in the unconsolidated deposits in the study area confirmed the presence of a bedrock valley dipping to the south in the central part of the study area. Water-level measurements in 2001 indicate that ground-water flow in much of the alluvial aquifer parallels the direction of flow in the Cedar River toward the south rather than following shorter flow paths to the west toward the Cedar River. Under steady-state conditions and 2001 pumpage, primary sources of inflow to the ground-water flow system are the Cedar River (65.5 percent), recharge through infiltration of precipitation and upland runoff (31.4 percent), and subsurface flow across the lateral boundaries (3.1 percent). The primary components of outflow from the ground-water flow system are intermittent streams (56.0 percent) and the Cedar River (43.7 percent). Two hypothetical scenarios were used to assess the potential effects of higher river levels and increased recharge compared to the steadystate conditions. For one scenario, river levels were set to bankfull conditions, and a recharge of 1.2 times the steady-state rate was applied. This simulation was used to evaluate the effects of wet conditions. This scenario led to increased water levels, in general, and large areas of shallow (0 to 10 feet) depths to water along the eastern part of the model area near Highway 218. For the second scenario, conditions were the same as for the first scenario, but streambed conductance of intermittent streams modeled as drains was increased to 10 times the steady-state value to simulate increased flow of water from the shallow groundwater flow system. The area with depth to water of 0 to 10 feet along the eastern part of the model area was substantially smaller than that of the first scenario. In general, once high ground-water levels occur, either because of high Cedar River water Abstract levels or above normal local precipitation or both, ground-water in the central part of the study area along Highway 218 flows toward the south rather than following shorter flow paths to the Cedar River. Intermittent streams in the study area discharge substantial amounts of water from the ground-water flow system.

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USGS2003

Bathymetric mapping, sediment quality, and water quality of Lake Delhi, Iowa, 2001-02

Lake Delhi was formed in 1929 when the Interstate Power Company dammed the Maquoketa River near Delhi, Iowa, for generation of hydroelectric power. The resulting 450-acre lake became a popular area in eastern Iowa for boating, swimming, and fishing. Hydroelectric power generation ended in 1973, and lakeside residents purchased the dam to maintain the recreational opportunities of the lake. Increasing concerns about sediment deposition and water quality by lakeside residents led to a 2-year study that included a bathymetric survey, an assessment of sediment quality, and an assessment of water quality of Lake Delhi. A bathymetric map of Lake Delhi was constructed using more than 300,000 data points from echo sounding results and GIS (geographic information system) software. Results of bathymetric mapping showed that the upstream reach through most of the upstream-middle reach of Lake Delhi (approximately 3 miles) from about 0.25 mile upstream from the Greenslades coring site through Clair View Acres were particularly affected by sedimentation, with water depths ranging from less than 1 foot to a few areas that were as much as 10 feet deep. Numerous areas in the upstream-most 1-mile of the lake (about 0.25 mile upstream from the Greenslades coring site to just downstream from The Cedars coring site) had depths of only 1 to 2 feet and were nearly impassable by boats. The middle reach of Lake Delhi (an approximately 2.5-mile segment) from about one-half mile upstream from the Linden Acres coring site to just downstream from the Hartwick Dredge coring site was less affected by sedimentation with water depths from less than 1 to 16 feet. The deepest section (26 feet) of the lake was near the dam. Eleven trace metals and phosphorus were analyzed in 20 samples from seven lake-bottom sediment cores. The median and average traceelement concentrations from the sediment cores were less than the U.S. Environmental Protection Agency threshold-effects-level and probableeffects-level guidelines for toxic biological effects. Water-quality samples from eight sites (Maquoketa River, three lake sites, and four tributaries) were collected for five sampling periods (June 2001–July 2002). Water-quality samples were analyzed for physical properties (specific conductance, pH, temperature, turbidity, dissolved oxygen, and alkalinity), nutrients (nitrate, ammonia, and phosphorus), bacteria (total coliform and E. coli ), and suspended sediment. Selected water samples were analyzed for major ions, trace elements, and pesticides. Water-quality sampling results indicate areas affected by elevated nutrient and bacteria concentrations in the lake and tributary streams. The tributary streams had the highest median nitrate concentrations (12.1 milligrams per liter) when compared to median nitrate concentrations in the lake (8.7 milligrams per liter) or the Maquoketa River (10.5 milligrams per liter). The maximum nitrate concentrations detected for Maquoketa River, lake, and tributary sites were 13.5, 13.5, and 18.6 milligrams per liter, respectively. Nitrate concentrations in the late summer decreased from 2 Bathymetric Mapping, Sediment Quality, and Water Quality of Lake Delhi, Iowa, 2001–02 the upstream (7.8 milligrams per liter) to the downstream (5.0 milligrams per liter) one-third of Lake Delhi and most likely were the result of uptake of nitrate by algae and aquatic biota in the lake. Median concentrations of total coliform and E. coli bacteria for the lake sites were 450 and 17 colonies per 100 milliliters of sample, respectively. The U.S. Environmental Protection Agency criteria for full body contact (swimming or bathing) are 200 colonies per 100 milliliters for fecal bacteria and 126 colonies per 100 milliliters for E. coli bacteria. The highest bacteria concentrations in the lake occurred after a rain and were 25,000 colonies per 100 milliliters total coliform and 1,900 colonies per 100 milliliters E. coli .

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USGS2003

Main-channel slopes of selected streams in Iowa for estimation of flood-frequency discharges

This report describes a statewide study conducted to develop main-channel slope (MCS) curves for 138 selected streams in Iowa with drainage areas greater than 100 square miles. MCS values determined from the curves can be used in regression equations for estimating floodfrequency discharges. Multivariable regression equations previously developed for two of the three hydrologic regions defined for Iowa require the measurement of MCS. Main-channel slope is a difficult measurement to obtain for large streams using 1:24,000-scale topographic maps. The curves developed in this report provide a simplified method for determining MCS values for sites located along large streams in Iowa within hydrologic Regions 2 and 3. The curves were developed using MCS values quantified for 2,058 selected sites along 138 selected streams in Iowa. A geographic information system (GIS) technique and 1:24,000-scale topographic data were used to quantify MCS values for the stream sites. The sites were selected at about 5-mile intervals along the streams. River miles were quantified for each stream site using a GIS program. Data points for river-mile and MCS values were plotted and a best-fit curve was developed for each stream. An adjustment was applied to all 138 curves to compensate for differences in MCS values between manual measurements and GIS quantifications. The multivariable equations for Regions 2 and 3 were developed using manual measurements of MCS. A comparison of manual measurements and GIS quantifications of MCS indicates that manual measurements typically produce greater values of MCS compared to GIS quantifications. Median differences between manual measurements and GIS quantifications of MCS are 14.8 and 17.7 percent for Regions 2 and 3, respectively. Comparisons of percentage differences between flood-frequency discharges calculated using MCS values of manual measurements and GIS quantifications indicate that use of GIS values of MCS for Region 3 substantially underestimate flood discharges. Mean and median percentage differences for 2- to 500-year recurrence- interval flood discharges ranged from 5.0 to 5.3 and 4.3 to 4.5 percent, respectively, for Region 2 and ranged from 18.3 to 27.1 and 12.3 to 17.3 percent for Region 3. The MCS curves developed from GIS quantifications were adjusted by 14.8 percent for streams located in Region 2 and by 17.7 percent for streams located in Region 3. Comparisons of percentage differences between flood discharges calculated using MCS values of manual measurements and adjusted-GIS quantifications for Regions 2 and 3 indicate that the flood-discharge estimates are comparable. For Region 2, mean percentage differences for 2- to 500-year recurrence- interval flood discharges ranged between 0.6 and 0.8 percent and median differences were 0.0 percent. For Region 3, mean and median differences ranged between 5.4 to 8.4 and 0.0 to 0.3 percent, respectively. A list of selected stream sites presented with each curve provides information about the sites including river miles, drainage areas, the location of U.S. Geological Survey streamflowgaging stations, and the location of streams crossing hydrologic region boundaries or the Des Moines Lobe landform region boundary. Two examples are presented for determining river-mile and MCS values, and two techniques are presented for computing flood-frequency discharges.

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USGS2002

Herbicide transport in rivers: Importance of hydrology and geochemistry in nonpoint-source contamination

Alachlor, atrazine, cyanazine, metolachlor, and metribuzin were measured at six sites during 1984 and 1985 in large subbasins within the Cedar River, IA. A computer model separated the Cedar River discharge hydrograph into groundwater and overland-flow components. The concentration of herbicides in the river when groundwater was the major flow component was less than 1.0 μ g/L and averaged 0.2 μ g/L. The maximum concentrations of herbicides occurred when overland flow was the major component of river discharge, exceeding 50 pg/L for total herbicides. About 6% of the annual river load of atrazine was transported with the groundwater component, while 94% was transported with overland flow. From 1.5 to 5% of the atrazine applied during the year was transported from the basin. Atrazine concentrations in the river in- creased according to the discharge divided by the drainage area. This correlation indicates that rivers with large normalized 2-year peak flows have the potential to transport large concentrations of herbicides. A diagrammatic model of nonpoint-source transport of herbicides was developed that suggests that sorbed transport from fields occurs during episodes of overland flow with rapid dissolution of herbicides downstream.

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USGS2002

Atrazine degradation in a small stream in Iowa

A study was conducted during 1990 through an 11.2-km reach of Roberts Creek in northeastern Iowa to determine the fate of atrazine in a surface water environment Water samples were collected at ~1-month intervals from April through November during stable low to medium flow conditions and analyzed for atrazine and two of its initial biotic degradation products, desethylatrazine and deisopropylatrazine. Samples were collected on the basis of a Lagrangian model of streamflow in order to sample the same parcel of water as it moved downstream. Atrazine concentrations substantially decreased (roughly 25-60%) between water entering and exiting the study reach during four of the seven sampling periods. During these same four sampling periods, the concentrations of the two biotic atrazine degradation products were constant or decreasing downstream, suggesting an abiotic degradation process.

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USGS2002

Herbicide interchange between a stream and the adjacent alluvial aquifer

Herbicide interchange between a stream and the adjacent alluvial aquifer and quantification of herbicide bank storage during high streamflow were investigated at a research site on the Cedar River flood plain, 10 km southeast of Cedar Rapids, Iowa. During high streamflow in March 1990, alachlor, atrazine, and metolachlor were detected at concentrations above background in water from wells as distant as 20, 50, and 10 m from the river's edge, respectively. During high streamflow in May 1990, alachlor, atrazine, cyanazine, and metolachlor were detected at concentrations above background as distant as 20, 50, 10, and 20 m from the river's edge, respectively. Herbicide bank storage took place during high streamflow when hydraulic gradients were from the river to the alluvial aquifer and the laterally infiltrating river water contained herbicide concentrations larger than background concentrations in the aquifer. The herbicide bank storage can be quantified by multiplying herbicide concentration by the "effective area" that a well represented and an assumed porosity of 0.25. During March 1990, herbicide bank storage values were calculated to be 1.7,79, and 4.0 mg/m for alachlor, atrazine, and metolachlor, respectively. During May 1990, values were 7.1, 54, 11, and 19 mg/m for alachlor, atrazine, cyanazine, and metolachlor, respectively.

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USGS2002

Chemical transport from paired agricultural and restored prairie watersheds

A five-year record of streamflow and chemical sampling data was evaluated to assess the effects of large-scale prairie restoration on transport of NO 3 –N, Cl, and SO 4 loads from paired 5000-ha watersheds located in Jasper County, Iowa. Water quality conditions monitored during land use conversion from row crop agriculture to native prairie in the Walnut Creek watershed were compared with a highly agricultural control watershed (Squaw Creek). Combining hydrograph separation with a load estimation program, baseflow and stormflow loads of NO 3 –N, Cl, and SO 4 were estimated at upstream and downstream sites on Walnut Creek and a downstream site on Squaw Creek. Chemical export in both watersheds was found to occur primarily with baseflow, with baseflow transport greatest during the late summer and fall. Lower Walnut Creek watershed, which contained the restored prairie areas, exported less NO 3 –N and Cl compared with upper Walnut Creek and Squaw Creek watersheds. Average flow-weighted concentrations of NO 3 –N exceeded 10 mg/L in upper Walnut Creek and Squaw Creek, but were estimated to be 6.6 mg/L in lower Walnut Creek. Study results demonstrate the utility of partitioning loads into baseflow and stormflow components to identify sources of pollutant loading to streams.

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USGS2002

Water resources data Iowa water year 2001, Volume 1. surface water--Mississippi River basin

Water resources data for water year 2000 for Iowa consists of records of stage, discharge, and water quality of streams; stage and contents of lakes and reservoirs; and water levels and water quality of ground water. This report, in two volumes, contains stage or discharge records for 126 gaging stations; stage or contents records for 9 lakes and reservoirs; water-quality records for 4 gaging stations; sediment records for 12 gaging stations; and water levels for 167 ground-water observation wells. Also included are peak-flow data for 93 crest-stage partial-record stations, water-quality data from 45 municipal wells, and precipitation data collected at 6 gaging stations and 2 precipitation sites. Additional water data were collected at various sites not included in the systematic data-collection program, and are published here as miscellaneous measurements and analyses. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating local, State, and Federal agencies in Iowa.

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USGS2002

Water resources data, Iowa, water year 2001, Volume 2. surface water--Missouri River basin, and ground water

The Water Resources Division of the U.S. Geological Survey, in cooperation with State, county, municipal, and other Federal agencies, obtains a large amount of data pertaining to the water resources of Iowa each water year. These data, accumulated during many water years, constitute a valuable data base for developing an improved understanding of the water resources of the State. To make this data readily available to interested parties outside of the Geological Survey, the data is published annually in this report series entitled “Water Resources Data - Iowa” as part of the National Water Data System. Water resources data for water year 2001 for Iowa consists of records of stage, discharge, and water quality of streams; stage and contents of lakes and reservoirs; and water levels and water quality of ground water. This report, in two volumes, contains stage or discharge records for 132 gaging stations; stage records for 9 lakes and reservoirs; water-quality records for 4 gaging stations; sediment records for 13 gaging stations; and water levels for 163 ground-water observation wells. Also included are peak-flow data for 92 crest-stage partial-record stations, water-quality data from 86 municipal wells, and precipitation data collected at 6 gaging stations and 2 precipitation sites. Additional water data were collected at various sites not included in the systematic data-collection program, and are published here as miscellaneous measurements and analyses. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating local, State, and Federal agencies in Iowa. Records of discharge or stage of streams, and contents or stage of lakes and reservoirs were first published in a series of U.S. Geological Survey water-supply papers entitled “Surface Water Supply of the United States.” Through September 30, 1960, these water-supply papers were published in an annual series; during 1961-65 and 1966-70, they were published in 5- year series. Records of chemical quality, water temperatures, and suspended sediment were published from 1941 to 1970 in an annual series of water-supply papers entitled “Quality of Surface Waters of the United States.” Records of ground-water levels were published from 1935 to 1974 in a series of water-supply papers entitled “Ground-Water Levels in the United States.” Water-supply papers may be consulted in the libraries of the principal cities in the United States, or they may be purchased from Books and Open-File Reports Section, Federal Center, Box 25425, Denver, Colorado 80225. For water years 1961 through 1970, streamflow data were released by the Geological Survey in annual reports on a State-boundary basis. Water-quality records for water years 1964 through 1970 were similarly released either in separate reports or in conjunction with streamflow records. Beginning with the 1971 water year, water data for streamflow, water quality, and ground water is published in official U.S. Geological Survey reports on a State-boundary basis. These official reports carry an identification number consisting of the two-letter State postal abbreviation, the last two digits of the water year, and the volume number. For example, this report is identified as “U.S. Geological Survey Water-Data Report IA-01-1.” These water-data reports are for sale by the National Technical Information Service, U.S. Department of Commerce, Springfield, Virginia 22161.

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USGS2002

Ground water near Pella and in selected parts of Jasper, Mahaska and Marion Counties, Iowa

The U.S. Geological Survey, in cooperation with the city of Pella, Iowa, conducted a study of the ground-water resources in selected parts of Jasper, Mahaska, and Marion Counties near Pella, Iowa, during 2000–01. The purpose of the study was to describe the ground-water resources in the Pella, Iowa, area. Following a review of available hydrologic and geologic information, the study focused on investigating the alluvial deposits along the South Skunk River within a 10-mile radius of the city of Pella. Thickness, lithologic, and water-quality data for the alluvial deposits in the South Skunk River Valley were collected at selected sites from August 2000 through July 2001. The South Skunk River alluvial aquifer near Pella consists of stratified deposits of sand and gravel of glacial and fluvial origin. The upper 15 to 20 feet of the alluvial deposits are interbedded with flood-plain clay and silt lenses and are overlain by a developed soil horizon. The alluvial aquifer is underlain by a thin (less than 50 feet thick) layer of glacial drift. Glacial drift, as it is defined in the study area, is a heterogeneous, unsorted, unstratified, unconsolidated, relatively impermeable deposit consisting of clay, sand, and gravel. The bedrock surface beneath the glacial drift consists primarily of shale and limestone of Pennsylvanian or Mississippian age. The alluvial sand and gravel deposits along the South Skunk River near Pella range from less than 30 to more than 80 feet thick. Saturated thickness of the alluvial aquifer ranges from 15 to about 70 feet. Water-quality samples were collected from four observation wells installed in the South Skunk River alluvial aquifer in the study area. Results of the water-quality sampling show that the chemical quality of the ground water is generally similar at all of the sampling sites. All ground-water samples were low in dissolved oxygen, which resulted in high concentrations of iron and manganese and reduced forms of nitrogen.

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