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Charles G. Crawford

Publications and source records attributed to Charles G. Crawford.

At least 37 records · Page 2Linked to original sources
USGS2007

Sampling strategies for estimating acute and chronic exposures of pesticides in streams

The Food Quality Protection Act of 1996 requires that human exposure to pesticides through drinking water be considered when establishing pesticide tolerances in food. Several systematic and seasonally weighted systematic sampling strategies for estimating pesticide concentrations in surface water were evaluated through Monte Carlo simulation, using intensive datasets from four sites in northwestern Ohio. The number of samples for the strategies ranged from 4 to 120 per year. Sampling strategies with a minimal sampling frequency outside the growing season can be used for estimating time weighted mean and percentile concentrations of pesticides with little loss of accuracy and precision, compared to strategies with the same sampling frequency year round. Less frequent sampling strategies can be used at large sites. A sampling frequency of 10 times monthly during the pesticide runoff period at a 90 km 2 basin and four times monthly at a 16,400 km2 basin provided estimates of the time weighted mean, 90th, 95th, and 99th percentile concentrations that fell within 50 percent of the true value virtually all of the time. By taking into account basin size and the periodic nature of pesticide runoff, costs of obtaining estimates of time weighted mean and percentile pesticide concentrations can be minimized.

Indiana, Michigan, Ohio↗
USGS2006

Pesticides in the Nation's Streams and Ground Water, 1992–2001

This report is one of a series of publications, The Quality of Our Nation's Waters, that describe major findings of the NAWQA Program on water-quality issues of regional and national concern. This report presents evaluations of pesticides in streams and ground water based on findings for the first decadal cycle of NAWQA. 'Pesticides in the Nation's Streams and Ground Water, 1992-2001' greatly expands the analysis of pesticides presented in 'Nutrients and Pesticides,' which was the first report in the series and was based on early results from 1992 to 1995. Other reports in this series cover additional water-quality constituents of concern, such as volatile organic compounds and trace elements, as well as physical and chemical effects on aquatic ecosystems. Each report builds toward a more comprehensive understanding of regional and national water resources. The information in this series is intended primarily for those interested or involved in resource management, conservation, regulation, and policymaking at regional and national levels. In addition, the information might interest those at a local level who wish to know more about the general quality of streams and ground water in areas near where they live and how that quality compares with other areas across the Nation.

Circular↗
USGS2006

Simulation of daily pesticide concentrations from watershed characteristics and monthly climatic data

A time-series model was developed to simulate daily pesticide concentrations for streams in the coterminous United States. The model was based on readily available information on pesticide use, climatic variability, and watershed charac-teristics and was used to simulate concentrations for four herbicides [atrazine, ethyldipropylthiocarbamate (EPTC), metolachlor, and trifluralin] and three insecticides (carbofuran, ethoprop, and fonofos) that represent a range of physical and chemical properties, application methods, national application amounts, and areas of use in the United States. The time-series model approximates the probability distributions, seasonal variability, and serial correlation characteristics in daily pesticide concentration data from a national network of monitoring stations. The probability distribution of concentrations for a particular pesticide and station was estimated using the Watershed Regressions for Pesticides (WARP) model. The WARP model, which was developed in previous studies to estimate the probability distribution, was based on selected nationally available watershed-characteristics data, such as pesticide use and soil characteristics. Normality transformations were used to ensure that the annual percentiles for the simulated concentrations agree closely with the percentiles estimated from the WARP model. Seasonal variability in the transformed concentrations was maintained by relating the transformed concentration to precipitation and temperature data from the United States Historical Climatology Network. The monthly precipitation and temperature values were estimated for the centroids of each watershed. Highly significant relations existed between the transformed concentrations, concurrent monthly precipitation, and concurrent and lagged monthly temperature. The relations were consistent among the different pesticides and indicated the transformed concentrations generally increased as precipitation increased but the rate of increase depended on a temperature-dependent growing-season effect. Residual variability of the transformed concentrations, after removal of the effects of precipitation and temperature, was partitioned into a signal (systematic variability that is related from one day to the next) and noise (random variability that is not related from one day to the next). Variograms were used to evaluate measurement error, seasonal variability, and serial correlation of the historical data. The variogram analysis indicated substantial noise resulted, at least in part, from measurement errors (the differences between the actual concen-trations and the laboratory concentrations). The variogram analysis also indicated the presence of a strongly correlated signal, with an exponentially decaying serial correlation function and a correlation time scale (the time required for the correlation to decay to e-1 equals 0.37) that ranged from about 18 to 66 days, depending on the pesticide type. Simulated daily pesticide concentrations from the time-series model indicated the simulated concentrations for the stations located in the northeastern quadrant of the United States where most of the monitoring stations are located generally were in good agreement with the data. The model neither consistently overestimated or underestimated concentrations for streams that are located in this quadrant and the magnitude and timing of high or low concentrations generally coincided reasonably well with the data. However, further data collection and model development may be necessary to determine whether the model should be used for areas for which few historical data are available.

Scientific Investigations Report↗
USGS2005

Development of an approach for integrating components of the U.S. Geological Survey Biomonitoring of Environmental Status and Trends (BEST) and National Stream Quantity Accounting Network (NASQAN) programs for large U.S. rivers

A national-scale framework for monitoring environmental contaminants in fish and effects of contaminant exposure on fish in large U.S. rivers has been proposed by the Biomonitoring of Environmental Status and Trends (BEST) Program of the U.S. Geological Survey (USGS). The framework shares many features and objectives with the USGS National Stream Quantity Accounting Network (NASQAN) Program, which monitors water quality in large U.S. river basins–those with drainage areas of 250,000 to 1,200,000 square miles at their most downstream stations. Because the two programs appear to be complementary, this study was initiated in 2001 to investigate alternative techniques for summarizing and integrating the water-quality data with the fish-contaminant and fish-health data, and to provide recommendations to the BEST program for future integrated studies.

Scientific Investigations Report↗
USGS2004

Load estimator (LOADEST): a FORTRAN program for estimating constituent loads in streams and rivers

LOAD ESTimator (LOADEST) is a FORTRAN program for estimating constituent loads in streams and rivers. Given a time series of streamflow, additional data variables, and constituent concentration, LOADEST assists the user in developing a regression model for the estimation of constituent load (calibration). Explanatory variables within the regression model include various functions of streamflow, decimal time, and additional user-specified data variables. The formulated regression model then is used to estimate loads over a user-specified time interval (estimation). Mean load estimates, standard errors, and 95 percent confidence intervals are developed on a monthly and(or) seasonal basis. The calibration and estimation procedures within LOADEST are based on three statistical estimation methods. The first two methods, Adjusted Maximum Likelihood Estimation (AMLE) and Maximum Likelihood Estimation (MLE), are appropriate when the calibration model errors (residuals) are normally distributed. Of the two, AMLE is the method of choice when the calibration data set (time series of streamflow, additional data variables, and concentration) contains censored data. The third method, Least Absolute Deviation (LAD), is an alternative to maximum likelihood estimation when the residuals are not normally distributed. LOADEST output includes diagnostic tests and warnings to assist the user in determining the appropriate estimation method and in interpreting the estimated loads. This report describes the development and application of LOADEST. Sections of the report describe estimation theory, input/output specifications, sample applications, and installation instructions.

Techniques and Methods↗
USGS2004

Development and Application of Watershed Regressions for Pesticides (WARP) for Estimating Atrazine Concentration Distributions in Streams

Regression models were developed for predicting atrazine concentration distributions in rivers and streams, using the Watershed Regressions for Pesticides (WARP) methodology. Separate regression equations were derived for each of nine percentiles of the annual distribution of atrazine concentrations and for the annual time-weighted mean atrazine concentration. In addition, seasonal models were developed for two specific periods of the year--the high season, when the highest atrazine concentrations are expected in streams, and the low season, when concentrations are expected to be low or undetectable. Various nationally available watershed parameters were used as explanatory variables, including atrazine use intensity, soil characteristics, hydrologic parameters, climate and weather variables, land use, and agricultural management practices. Concentration data from 112 river and stream stations sampled as part of the U.S. Geological Survey's National Water-Quality Assessment and National Stream Quality Accounting Network Programs were used for computing the concentration percentiles and mean concentrations used as the response variables in regression models. Tobit regression methods, using maximum likelihood estimation, were used for developing the models because some of the concentration values used for the response variables were censored (reported as less than a detection threshold). Data from 26 stations not used for model development were used for model validation. The annual models accounted for 62 to 77 percent of the variability in concentrations among the 112 model development stations. Atrazine use intensity (the amount of atrazine used in the watershed divided by watershed area) was the most important explanatory variable in all models, but additional watershed parameters significantly increased the amount of variability explained by the models. Predicted concentrations from all 10 models were within a factor of 10 of the observed concentrations at most model development and model validation stations. Results for the two sets of seasonal models were similar. Concentration distributions derived from the seasonal-model predictions provided additional information compared to distributions derived from the annual models.

Water-Resources Investigations Report↗
USGS1999

Environmental setting and natural factors and human influences affecting water quality in the White River Basin, Indiana

The White River Basin drains 11,349 square miles of central and southern Indiana and is one of 59 Study Units selected for water-quality assessment as part of the U.S. Geological Survey's National WaterQuality Assessment Program. Defining the environmental setting of the basin and identifying the natural factors and human influences that affect water quality are important parts of the assessment. Interrelated natural factors help determine the quality of surface and ground water in a river basin. The White River Basin has a humid continental climate, characterized by well-defined winter and summer seasons. Geologic features in the basin include glaciated and nonglaciated areas; a region of karst geomorphology that is characterized by caves and sinkholes; and a thick, sedimentary bedrock sequence underlying the entire basin. Unconsolidated glacial deposits of clay, silt, sand and gravel cover more than 60 percent of the basin. Soils developed in unconsolidated glacial deposits are typically fertile, naturally or artificially well drained, and farmed. Soils in the unglaciated south-central part of the basin are thin, have low fertility, and are best suited for forest or pasture. Agriculture is the principal land use in the White River Basin. Approximately 70 percent of the basin is used for agriculture, and about 50 percent of the basin is cropland. Corn and soybeans are the major crops. Other significant land uses are forest (22 percent) and urban and residential (7 percent). The population of the basin was 2.1 million in 1990. Water use in the White River Basin totaled 1,284 million gallons per day in 1995, of which 84.5 percent was surface water and 15.5 percent was ground water. Despite the predominant use of surface water, ground water was the primary source of drinking water for approximately 56 percent of the population. The general water chemistry in the White River Basin is determined by natural factors such as soils and geologic materials that water contacts as it moves through the hydrologic system. In the southern part of the basin, bedrock upland areas are dominated by non-carbonate bedrock, thin soils, and high runoff-rainfall ratios. These areas have small chemical concentrations in streamwater. Conversely, in the northern part of the basin where glacial deposits are thick and in the southwestern part of the basin where loess deposits are thick, water has longer periods of time to react with soils and aquifers and to acquire substantial quantities of dissolved constituents. As a result, streams in the till plain and glacial lowland have higher concentrations of most constituents than streams in the unglaciated parts of the basin. Water quality is significantly modified by human influences. Water quality is affected locally by point sources of contamination that include combined-sewer overflows, power-generation-plant cooling stations, and wastewater-treatment-plant effluents that are generally associated with densely populated areas. Water quality is additionally affected by non-point sources of contamination related to agriculture, urban runoff, and mining. Six hydrogeomorphic regions of the White River Basin are delineated on the basis of distinct and relatively homogeneous natural characteristics. These six regions are used in the White River Basin study as a framework for examining the effects of natural factors on water quality in the basin. Bedrock is exposed or near the surface in three hydrogeomorphic regions the bedrock uplands, bedrock lowland and plain, and karst plain; streams and shallow aquifers in these regions are susceptible to contamination, especially in the karst plain, and show rapid response to rainfall. The other three hydrogeomorphic regions the fluvial deposits, till plain, and glacial lowland are in the glaciated part of the basin. Where thick fine-grained unconsolidated sediments are present, primarily in the till plain, ground-water supplies are protected from contamination, and extreme high and low streamflows are moderated.

Indiana↗
USGS1997

Trends in acetochlor concentrations in surface waters of the White River Basin, Indiana, 1994–96

Corn herbicides are used extensively in the White River Basin and account for about 70 percent of the total agricultural pesticide use in the basin. Acetochlor, a corn herbicide registered for use in 1994, is expected to reduce the total amount of corn herbicides used because of its broad-spectrum weed control and low use rates. Acetochlor is considered to be a probable human carcinogen, and its continued registration is contingent on concentrations in surface and ground water not exceeding target levels. During 1994, acetochlor was detected in only trace concentrations near the mouth of the White River and not at all in a small stream (93-square-mile drainage) in the northern part of the basin. By 1996, peak concentrations were about 2 and 3 micrograms per liter near the mouth of the White River and in the small stream, respectively. The estimated annual average concentration of acetochlor near the mouth of the White River in 1996 was 0.15 micrograms per liter, well below the 2 micrograms per liter criterion for surface-water supplied community-water systems.

Indiana↗
USGS1996

Comparison of gas chromatography/mass spectrometry and immunoassay techniques on concentrations of atrazine in storm runoff

Gas chromatography/mass spectrometry (GC/MS) and enzyme-linked immunosorbent assay (ELISA) techniques were used to measure concentrations of dissolved atrazine in 149 surface-water samples. Samples were collected during May 1992–September 1993 near the mouth of the White River (Indiana) and in two small tributaries of the river. GC/MS was performed on a Hewlett-Packard 5971 A, with electron impact ionization and selected ion monitoring of filtered water samples extracted by C-18 solid phase extraction; ELISA was performed with a magnetic-particle-based assay with photometric analysis. ELISA results compared reasonably well to GC/MS measurements at concentrations below the Maximum Contaminant Level for drinking water set by the U.S. Environmental Protection Agency (3.0 μg/L), but a systematic negative bias was observed at higher concentrations. When higher concentration samples were diluted into the linear range of calibration, the relation improved. A slight positive bias was seen in all of the ELISA data compared to the GC/MS results, and the bias could be partially explained by correcting the ELISA data for cross reactivity with other triazine herbicides. The highest concentrations of atrazine were found during the first major runoff event after the atrazine was applied. Concentrations decreased throughout the rest of the sampling period even though large runoff events occurred during this time, indicating that most atrazine loading to surface waters in the study area occurs within a few weeks after application. Use of brand names is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey, the Uniroyal Chemical Company, or Wichita State University.

Indiana↗
USGS1996

Influence of natural and human factors on pesticide concentrations in surface waters of the White River Basin, Indiana

Pesticide concentrations in surface waters of the White River Basin are affected by natural and human factors. For example, concentrations of atrazine, a herbicide widely used on corn in the White River Basin, tended to be higher in an agricultural basin with permeable, well-drained soils, than in an agricultural basin with less permeable, more poorly drained soils. Concentrations of butylate, another herbicide used on corn, were substantially higher in an agricultural basin in the southern part of the White River Basin than in an agricultural basin in the central part of the White River Basin, corresponding to the higher use of this compound in southern Indiana. Concentrations of diazinon were substantially higher in a predominantly urban basin than in two predominantly agricultural basins, corresponding to the common use of this insecticide on lawns and gardens in urban areas.

Indiana↗
USGS1996

Water-quality assessment of the White River Basin, Indiana: Analysis of selected information on nutrients, 1980-92

Water-quality data from 23 surfacewater-quality monitoring sites operated by the Indiana Department of Environmental Management and streamflow data from 11 U.S. Geological Survey streamflow-gaging stations in the White River Basin were analyzed to determine recent (1981 90 water years) water-quality conditions, trends, and river loads for ammonia, nitrate, total nitrogen, and total phosphorus. The White River Basin drains 11,349 square miles of central and south-central Indiana and is divided into two nearly equal subbasins the East Fork White River and the White River upstream from its confluence with the East Fork (called the "west fork" of the White River by the State's water-management agencies). Nutrient concentrations generally were higher in the more urbanized west fork than in the more rural east fork because of the much larger volumes of treated municipal sewage, combined-sewer overflows, and urban runoff discharged to the west fork. Concentrations of nutrients, especially ammonia and total phosphorus, were higher downstream from Muncie, Anderson, and Indianapolis than they were upstream from these cities. Nutrient concentrations decreased downstream from Indianapolis in the White River and in the downstream reach of the East Fork White River because of dilution, nitrification, adsorption to stream-bottom sediments, and uptake by aquatic vegetation. Seasonal variations in nutrient concentrations and the relations of nutrient concentrations to streamflow depended on the relative contributions of point and nonpoint sources of the nutrients. Total phosphorus increased with increasing streamflow at monitoring sites on the east fork but decreased with increasing streamflow at sites on the west fork. Increasing concentrations of phosphorus with increasing streamflow were consistent with nonpoint sources of phosphorus that wash off land surfaces, whereas decreasing concentrations of phosphorus with increasing streamflow were consistent with dilution of point sources of phosphorus. Median concentrations of total phosphorus were highest during summer and fall downstream from urban areas on the White River because streamflows that dilute point sources of phosphorus are lowest during summer and fall. Median concentrations of ammonia in the White River were highest in winter because of reduced biological uptake and nitrification of ammonia during cold temperatures.

Indiana↗
USGS1996

Fishes of the White River basin, Indiana

Since 1875, researchers have reported 158 species of fish belonging to 25 families in the White River Basin. Of these species, 6 have not been reported since 1900 and 10 have not been reported since 1943. Since the 1820's, fish communities in the White River Basin have been affected by the alteration of stream habitat, overfishing, the introduction of non-native species, agriculture, and urbanization. Erosion resulting from conversion of forest land to cropland in the 1800's led to siltation of streambeds and resulted in the loss of some silt-sensitive species. In the early 1900's, the water quality of the White River was seriously degraded for 100 miles by untreated sewage from the City of Indianapolis. During the last 25 years, water quality in the basin has improved because of efforts to control water pollution. Fish communities in the basin have responded favorably to the improved water quality.

Indiana↗
USGS1996

Suspended-sediment characteristics of Indiana streams, 1952-84

Suspended-sediment concentration and discharge data were collected at 7 daily record stations and 70 partial-record stations during 1952- 84. Median suspended-sediment concentrations ranged from 24 to 61 milligrams per liter at daily record stations; concentrations ranged from 6 to 539 milligrams per liter at partial-record stations. Most suspended sediment transported in Indiana streams is silt and clay size (particles between 0.062 and 0.004 millimeter in diameter and particles less than 0.004 millimeter in diameter). Large suspended-sediment concentrations were associated with storm runoff but not always with peak streamflow. Some peak concentrations of suspended sediment preceded peak streamflow by as much as 18 to 30 hours during storms. Suspended-sediment concentrations frequently were largest during a storm that occurred after a period of low streamflow, when large amounts of sediment were eroded and transported into the stream and little base flow was available for dilution. For most of the streams studied, reliable predictive equations could not be developed to quantify the relation between suspended-sediment concentration and streamflow because of the extreme variability in the data. Annual suspended-sediment yields at four daily record stations ranged from 186 to 1,914 tons per square mile. Annual suspended-sediment yields for 70 partial-record stations, estimated by use of the suspended-sediment transport, flowduration-curve method, ranged from 11 to 2,310 tons per square mile. However, because of the poor correlation between suspended-sediment discharge and streamflow, these estimates are imprecise. Periods of record at 4 daily record and 32 partial-record stations were sufficient to test for trends. The trend in suspended-sediment concentration, adjusted for streamflow, was significant for only 9 of the 36 stations. At six of the nine stations, flow-adjusted suspended-sediment concentrations decreased with time.

Indiana↗
USGS1995

Occurrence of pesticides in the White River, Indiana, 1991-95

Pesticides (herbicides and insecticides) are used extensively in the White River Basin. Application of herbicides to corn and soybeans accounts for most of the use. The pesticides most frequently detected near the mouth of the White River during 1991-95 were the herbicides alachlor, atrazine, cyanazine, and metolachlor. The highest concentrations of herbicides in the river were typically found during late spring runoff following application. Generally, concentrations of alachlor have been decreasing while concentrations of acetochlor have been increasing in response to changes in the use of these herbicides in the basin. The total amount of the commonly used herbicides transported by the river is about 1 percent or less of the amount applied to cropland. Insecticides commonly used in urban and agricultural areas also were found but in much lower concentrations than commonly used herbicides.

Indiana↗
USGS1995

Water-quality assessment of the White River Basin, Indiana: Analysis of available information on pesticides, 1972-92

An analysis of historical pesticide data (1972-92) for the White River was conducted as part of the U.S. Geological Survey National Water-Quality Assessment Program. Data on the presence of pesticides in streams, bottom sediments, fish, and ground waters were examined. Results are interpreted with respect to spatial, seasonal, and streamflow effects. Concentrations of water-soluble pesticides reach a peak during the first storm following application and remain elevated for 1 to 2 months. The most herbicide loading to the White River occurs during this time, when about 1 percent of the applied herbicides are transported out of the White River Basin. Bottom sediments and fish were analyzed for lipophilic pesticides. Dieldrin, components of technical chlordane, and DDT-related compounds were the most frequently detected. In areas where pesticide concentrations in sediment were high, concentrations in fish were high, indicating that bottom sediments are probably the primary source of lipophilic pesticides in aquatic biota. Ground- water/surface-water interaction and the presence of pesticides in ground waters were examined. The bedrock karst region had the highest degree of ground-water/surface-water interaction, indicating that the shallow ground water is susceptible to contamination from surface sources. Atrazine was the most frequently detected pesticides in ground waters. All wells where pesticides were detected are in karst or alluvial outwash, indicating that these geomorphic units are highly susceptible to contamination.

Indiana↗
USGS1993

Effects of advanced treatment of municipal wastewater on the White River near Indianapolis, Indiana: Trends in water quality, 1978-86

The City of Indianapolis has constructed state-of-the-art advanced municipal wastewater-treatment systems to enlarge and upgrade the existing secondary-treatment processes at its Belmont and Southport treatment plants. These new advanced-wastewater-treatment plants became operational in 1983. A nonparametric statistical procedure--a modified form of the Wilcoxon-Mann-Whitney rank-sum test--was used to test for trends in time-series water-quality data from four sites on the White River and from the Belmont and Southport wastewater-treatment plants. Time-series data representative of pre-advanced- (1978-1980) and post-advanced- (1983--86) wastewater-treatment conditions were tested for trends, and the results indicate substantial changes in water quality of treated effluent and of the White River downstream from Indianapolis after implementation of advanced wastewater treatment. Water quality from 1981 through 1982 was highly variable due to plant construction. Therefore, this time period was excluded from the analysis. Water quality at sample sites located upstream from the wastewater-treatment plants was relatively constant during the period of study (1978-86). Analysis of data from the two plants and downstream from the plants indicates statistically significant decreasing trends in effluent concentrations of total ammonia, 5-day biochemical-oxygen demand, fecal-coliform bacteria, total phosphate, and total solids at all sites where sufficient data were available for testing. Because of in-plant nitrification, increases in nitrate concentration were statistically significant in the two plants and in the White River. The decrease in ammonia concentrations and 5-day biochemical-oxygen demand in the White River resulted in a statistically significant increasing trend in dissolved-oxygen concentration in the river because of reduced oxygen demand for nitrification and biochemical oxidation processes. Following implementation of advanced wastewater treatment, the number of river-quality samples that failed to meet the water-quality standards for ammonia and dissolved oxygen that apply to the White River decreased substantially.

Indiana↗
USGS1992

Recovery of benthic-invertebrate communities in the White River near Indianapolis, Indiana, USA, following implementation of advanced treatment of municipal wastewater

The City of Indianapolis, Indiana, USA, completed construction of advanced-wastewater-treatment systems to enlarge and upgrade existing secondary-treatment processes at the City’s two municipal wastewater-treatment plants in 1983. These plants discharge their effluent to the White River. A study was begun in 1981 to evaluate the effects of municipal wastewater on the quality of the White River near Indianapolis. As part of this study, benthic-invertebrate samples were collected from one riffle upstream and two riffles downstream from the treatment plants annually from 1981 through 1987 (2 times before and 5 times after the plant improvements became operational). Samples were collected during periods of late-summer or early-fall low streamflow with a Surber sampler. Upstream from the wastewater-treatment plants, mayflies and caddisflies were the predominant organisms in the benthic-invertebrate community (from 32 to 93 percent of all organisms; median value is 67 percent) with other insects and mollusks also present. Before implementation of advanced wastewater-treatment, the benthic-invertebrate community downstream from the wastewater treatment plants was predominantly chironomids and oligochaetes (more than 98 percent of all organisms)-organisms that generally are tolerant of organic wastes. Few intolerant species, such as mayflies or caddisflies were found. Following implementation of advanced wastewater treatment, mayflies and caddisflies became numerically dominant in samples collected downstream from the plants. By 1986, these organisms accounted for more than 90 percent of all organisms found at the two downstream sites. The diversity of benthic invertebrates found in these samples resembled that at the upstream site. The improvement in the quality of municipal wastewater effluent resulted in significant improvements in the water quality of the White River downstream from Indianapolis. These changes in river quality, in turn, have resulted in a shift from mostly pollution-tolerant to mostly pollution-intolerant organisms in the benthic-invertebrate community of the White River downstream from Indianapolis. The recovery was not immediate, however, with one of the downstream sites requiring 3 years before pollution-intolerant organisms became numerically dominant.

Indiana↗