Geology topics

Research about Clayton County, Iowa

Source-linked reports with geographic coverage including Clayton County, Iowa.

7 recordsLinked to original sources

USGS2007

Using a Geographic Information System to determine the relation between stream quality and geology in the Roberts Creek watershed, Clayton County, Iowa

A geographic information system (GIS) was used to determine the relation between the stream-water quality and underlying geology in Roberts Creek watershed, Clayton County, Iowa, for base-flow conditions during the spring and summer of 1988–90. Geologic, stream, basin and subbasin boundaries, and water-quality sampling-site coverages were created by digitizing available maps. A contour coverage was created from digital line-graph data. The areal extent of geologic units subcropping in each subbasin was quantified with GIS, and the results then were output and joined with the discharge and water-quality data for statistical analyses. Illustrations showing the geology of the study area and the results of the study were prepared using GIS. By using GIS and a statistical software package, a weak but statistically significant relation was found between the water temperature, pH, and nitrogen concentrations in Roberts Creek and the underlying geology during base-flow conditions.

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USGS2007

Relation between stream-water quality and geohydrology during base-flow conditions, Roberts creek watershed, Clayton County, Iowa

An investigation to determine the relation between stream water quality and geohydrology in the Roberts Creek watershed, Clayton County, Iowa, was conducted during selected base-flow periods in 1988-90. Discharge measurements were made and water samples collected for analyses of nutrients and selected herbicides in 19 subbasins along the main stem and tributaries of Roberts Creek. The areal extent of unconsolidated and bedrock units subcropping in each subbasin was quantified. The hydrologic data were correlated statistically with the geologic data to determine relations. Roberts Creek generally gained water and had larger nitrogen concentrations in subbasins in which loess and alluvial material were underlain primarily by low-permeability till and shale units. Roberts Creek generally lost water and had lower nitrate concentrations in subbasins with subcropping karstic units. Nitrogen concentrations decreased in streams underlain by the karstic units because the nitrogen removed by biological processes was not replaced by ground-water inflow. Seepage from Roberts Creek to ground water in areas of subcropping karstic carbonate rocks reduced the flow, which reduced the velocity, causing increased residence time of water in the stream. The additional residence time may allow additional time for biological processes to remove nitrogen from solution. There was no significant relation between dissolved orthophosphate or atrazine and the underlying geology.

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USGS1995

Agricultural chemicals in ground and surface water in a small watershed in Clayton County, Iowa, 1988-91

An investigation was conducted from October 1988 through September 1991 to (1) describe the quality of water in shallow, unconsolidated materials in the 1.09-square-mile Deer Creek watershed in Clayton County, Iowa, and to (2) define the quantity and seasonal distribution of selected agricultural chemicals in water from this watershed. Surficial unconsolidated aquifer materials that discharge water to Deer Creek include alluvium, loess, and glacial till. More than 80 percent of the watershed is used for row and cover crops. Median nitrate concentrations ranged from 16 mg/L (milligrams per liter) in water from the top of the 10-foot thick alluvial aquifer to less than 0.10 mg/L near the bottom. Atrazine was detected in more than 85 percent of the ground-water samples collected at or less than 5.5 feet below land surface. Only one sample collected at 7.0 feet below land surface in the alluvial aquifer had an atrazine concentration greater than the detection limit of 0.10 ug/L (micrograms per liter). Nitrogen and herbicide concentrations were largest in late spring and early summer. Sources of agricultural chemicals in the alluvial aquifer include vertical infiltration through the soil and lateral transport from upslope unconsolidated materials. Nitrogen was present in all water samples from Deer Creek. Nitrate concentrations ranged from 0.70 to 17 mg/L. Alachlor was detected in 11 percent of the samples, atrazine in 69 percent, cyanazine in 19 percent, and metolachlor in 33 percent. Alachlor concentrations ranged from less than 0.10 to 0.53 ug/L, atrazine ranged from less than 0.10 to 55 ug/L, cyanazine ranged from less than 0.10 to 12 ug/L, and metolachlor ranged from less than 0.10 to 69 ug/L. Herbicide detections occurred most frequently in late spring and early summer during or just following chemical application. Overland flow is an important source of nitrogen and herbicides to Deer Creek. Substantial amounts of agricultural chemicals are transported from the watershed. As much as 4,700 pounds, or 6.7 pounds per acre, of nitrogen were estimated to be transported from the watershed in 1 year. Nitrogen loads transported from the Deer Creek watershed were less during dry years than during years with average or greater than average rainfall.

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USGS1992

Hydrologic data for the Big Spring basin, Clayton County, Iowa, water year 1990

Hydrologic data were collected in the Big Spring basin located in Clayton County, Iowa, during the 1990 water year. The data were collected by the U.S. Geological Survey in cooperation with the Iowa Department of Natural Resources, Geological Survey Bureau, to provide information on variation and movement of agricultural chemicals in the hydrologic cycle in the basin. Precipitation, surface-water, and ground-water data were collected. Rainfall recorded during water year 1990 at a monitoring site on Roberts Creek totaled 43.67 inches. The greatest monthly rainfall (14.45 inches) occurred in August. Calcium and sulfate were the predominant ions in the rain, and the median concentrations of nitrate and ammonia as nitrogen were 0.35 and 0.48 milligrams per liter, respectively. Stream discharge, specific conductance, pH, and water temperature were monitored continuously, and monthly water-quality samples were collected at three sites in the basin. The predominant ions in samples from Roberts Creek at the point where it leaves the basin were calcium, magnesium, and bicarbonate. Nitrite plus nitrate as nitrogen concentrations in 42 samples ranged from less than 0.10 to 18 milligrams per liter. Pesticide concentrations in 34 samples ranged from less than 0.10 to 12 micrograms per liter. Alachlor was detected in 56 percent of the samples; atrazine in 100 percent; cyanazine in 68 percent; and metolachlor in 47 percent. At Big Spring, the ground-water discharge point, the daily mean specific conductance ranged from 378 to 796 microsiemens per centimeter at 25 degrees Celsius, the daily median pH ranged from 6.5 to 7.2, and the daily mean water temperature ranged from 5.5 to 11.5 degrees Celsius. Calcium, magnesium, and bicarbonate generally were the predominant ions in solution. Concentrations of nitrite plus nitrate as nitrogen in 32 samples ranged from 3.4 to 16 milligrams per liter. Alachlor was detected in 22 percent of the samples; atrazine in 100 percent; cyanazine in 44 percent, and metplachlor in 6 percent. The maximum atrazine concentration was 4.5 micrograms per liter. During a low-flow seepage study, May 29 and 30,1990, the measured discharge lost by streams in the basin was 8.56 cubic feet per second, the measured dissolved nitrogen load lost was 0.29 ton per day, and the measured atrazine load lost was 0.028 pound per day. The total measured discharge and total dissolved nitrogen load leaving the basin in streams were 3.63 cubic feet per second and about 0.04 ton per day, respectively.

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USGS1991

Hydrologic data for the Big Spring basin, Clayton County, Iowa; water year 1989

Hydrologic data were collected in the Big Spring Basin located in Clayton County, Iowa, during the 1989 water year. The data were collected in cooperation with the Iowa Department of Natural Resources, Geological Survey Bureau, to provide information on variation and movement of agricultural chemicals in the hydrologic cycle in the Big Spring Basin. Precipitation, stream, and ground-water data were collected. Total rainfall in the basin ranged from 20.0 to 24.4 inches. The greatest monthly rainfall was in August. Calcium and sulfate were the predominant ions in the rain and the median nitrate and ammonia concentrations as nitrogen were 0.40 and 0.63 mg/L (milligrams per liter), respectively. Stream discharge, water temperature, specific conductance, and pH were monitored continuously, and monthly water-quality samples were collected at three sites in the basin. The predominant ions in Roberts Creek, at the site where it leaves the basin, were calcium, magnesium, and bicarbonate. Nitrate plus nitrite as nitrogen concentrations ranged from 0.2 to 6.2 mg/L. Pesticide concentrations in 23 samples ranged from less than 0.10 μ /L (micrograms per liter) to 4.4 μ /L. Atrazine was detected in 100 percent of the samples, cyanazine and metolachlor in 43 percent of the samples and alachlor in 35 percent of the samples. At Big Spring, the ground-water discharge point, the daily mean water temperature ranged from 5.1 to 10.6 degrees Celsius, the daily mean specific conductance ranged from 271 to 793 micro Siemens per centimeter at 25 degrees Celsius, and the daily median pH ranged from 63 to 7.1. Calcium, magnesium, and bicarbonate were the predominant ions in solution. Nitrate plus nitrite as nitrogen concentrations ranged from 2.0 to 7.4 mg/L. Atrazine was detected in 95 percent of the samples, cyanazine was detected in 26 percent of the samples, and metolachlor and alachlor were detected in 16 percent of the samples. The maximum atrazine concentration was 3.3 μ /L. Water levels in the unconsolidated aquifers and the Galena aquifer were highest in the spring after snowmelt and in September after the greatest monthly rainfall. Water levels in the Saint Peter aquifer declined by approximately 0 J to 3.0 feet. During a baseflow seepage study, August 16 and 17, the measured discharge lost by streams in the basin was 2.82 cubic feet per second, the measured dissolved nitrogen load lost was 80 pounds per day, and the measured atrazine load lost was 0.002 pound per day. The total measured discharge and total dissolved nitrogen load leaving the basin in streams was 0.07 cubic feet per second and less than 20 pounds per day, respectively.

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USGS1989

Hydrologic data for the Big Spring basin, Clayton County, Iowa, water year 1988

Hydrologic data was collected during the 1988 water year in cooperation with the Iowa Department of Natural Resources Geological Survey Bureau in the Big Spring ground-water basin located in Clayton County, Iowa. Information on precipitation, streams, and ground water was collected in the basin. Total rainfall at Big Spring was 24.08 inches. The greatest monthly rainfall was in September. Calcium and sulfate were the predominant ions in the rain and the median ammonia and nitrate concentrations as nitrogen were 0.40 and 0.37 mg/L (milligrams per liter), respectively. Stream discharge, water temperature, specific conductance, and pH were monitored continuously and monthly water-quality samples were collected at three sites in the basin. In the streams, water temperature and pH vary diurnally and are greatest during the day. Specific conductance varies inversely with water temperature and pH. The predominant ions in the streams were calcium, magnesium, and bicarbonate. Nitrate plus nitrite as nitrogen concentrations ranged from 0.5 to 15 mg/L. Pesticide concentrations ranged from less than 0.10 µ g/L (micrograms per liter) to 0.72 µ g/L. Atrazine was detected in 12 of 13 stream samples and cyanazine was detected in 4 of 13 samples. The daily mean temperature of the water in Big Spring ranged from 9.7 to 10.6 degrees Celsius, the daily mean specific conductance ranged from 698 to 735 microsiemens per centimeter at 25 degrees Celsius, and the daily median pH ranged from 6.7 to 7.1. Calcium, magnesium, and bicarbonate were the predominant ions in solution. Nitrate plus nitrite as nitrogen concentrations ranged from 7.5 to 11 mg/L. Atrazine was the only pesticide detected in the monthly samples from Big Spring. Atrazine concentrations were greater than the detection limit in six of seven samples and ranged from less than 0.10 to 0.26 µ g/L. During a baseflow seepage study, June 28 and 29, the discharge lost by streams in the basin was 5.57 cubic feet per second and the dissolved nitrogen load lost was 0.19 tons per day. The discharge and total dissolved nitrogen leaving the basin in streams was 2.93 cubic feet per second and 0.02 tons per day, respectively.

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USGS1961

Geology and ground-water resources of Clayton County, Iowa

Clayton County includes 784 square miles in northeastern Iowa and in 1960 had a population of 21, 962. For the most part, the county is a dissected upland that is drained mainly by the southeastward flowing Turkey River and its principal tributary, the Volga River. The Turkey River empties into the Mississippi River, which flows southward along the eastern border of the county. The climate is humid continental, and the average annual precipitation is 33.01 inches. The economy of the county is based on farming and the raising of livestock. The natural resources of the county include soil, water, rock, sand, and timber.

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