Water Quality of the Flint River Basin, Alabama and Tennessee, 1999-2000
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Water Quality of the Flint River Basin, Alabama and Tennessee, 1999-2000 By Anne B. Hoos, Jerry W. Garrett, and Rodney R. Knight ABSTRACT Less than 5 percent of the estimated mass of pesticides applied annually to agricultural areas The U.S. Geological Survey monitored in the Flint River Basin was transported to the eight stream sites in the Flint River Basin during stream at the monitoring points on the Flint River the period January 1999 through May 2000, to near Brownsboro, Alabama, and on Hester Creek characterize patterns in the occurrence of pesti- near Plevna, Alabama. The pesticides with the cides, fecal-indicator bacteria, and nutrients in highest ratios (greater than 3 percent) of the relation to season and streamflow conditions and amount transported instream to the amount to land-use patterns. This study is part of the applied—atrazine, metolachlor, fluometuron, and National Water-Quality Assessment Program, norflurazon—are preemergent herbicides applied which was designed to assess water quality as it to the soil before the crops have emerged, which relates to various land uses. increases the probability of transport in surface Every water sample collected from the Flint runoff. River Basin had detectable levels of at least two Concentrations of the fecal-bacteria indica- pesticides; 64 percent of the samples contained tor Escherichia coli (E. coli) in the Flint River and mixtures of at least five pesticides. In general, Hester Creek exceeded the U.S. Environmental pesticides detected most frequently and at highest Protection Agency criterion for recreation in concentrations in streams corresponded to the almost all storm samples, and in many samples pesticides with the highest rates of use in the collected up to 6 days following a storm. Concen- watersheds. Detections of fluometuron, norflura- trations in the Flint River were strongly correlated zon, and atrazine were more frequent (by a mar- with sample turbidity, suggesting that turbidity gin of 15 percent or more) in samples from the might be useful as a surrogate for estimating Flint River when compared with the frequencies E. coli concentrations. Concentrations of the of pesticide detections at 62 agricultural stream nutrients nitrogen and phosphorus in samples sites across the Nation. Detections of fluometuron from the Flint River generally exceeded thresh- in the Flint River were more frequent even when olds indicating eutrophic potential, whereas con- compared with a cotton-cultivation subset of the centrations in samples from Hester Creek were 62 sites. For most pesticides, maximum concen- generally below the thresholds. When compared trations did not exceed criteria to protect aquatic with nutrient data from a set of 24 agricultural life; however, maximum concentrations of atra- basins across the southeastern region of the zine, cyanazine, and malathion exceeded aquatic- United States, concentrations in the Flint River life criteria in at least one sample. Concentrations and Hester Creek were slightly above the regional near or exceeding the aquatic-life criteria median. occurred only during the spring and summer Base-flow concentrations of certain pesti- (April-July), and generally occurred during storm cides, nutrients, and E. coli were compared to flows. land-use information for eight sites in the Flint Abstract 1 River Basin. The highest base-flow concentra- section (fig. 2), an area of well drained soils and gently tions of aldicarb sulfoxide, fluometuron, and rolling terrain that contains productive farmland (pre- phosphorus were found in the tributaries with the dominantly cotton, corn, and soybeans). The eastern greatest density of cotton acreage in the water- and southwestern edges lie on the escarpment of the shed. Similarly, high base-flow concentrations of Cumberland Plateau (fig. 2), which is characterized by total nitrogen were correlated with a high percent- steeply sloping forested land with pasture and culti- vated land restricted to the narrow valley floors. age of cultivated land in the watershed. Lack of Stream channels throughout the Flint River Basin are information about distribution of stream access by characterized by gravel and bedrock bottoms with livestock weakened the analysis of correlation numerous springs and spring-associated fish fauna. between livestock and base-flow concentrations The U.S. Geological Survey (USGS) National of E. coli and nutrients. Water-Quality Assessment (NAWQA) Program is cur- Input of dissolved and suspended chemicals rently investigating water quality in the lower Tennes- from the Flint River during storms influences see River Basin (fig. 1, map inset), with several water quality in the reach of the Tennessee River monitoring activities targeted in the Flint River Basin. from which the City of Huntsville, Alabama, The purpose of this investigation is to assess surface- withdraws about 40 percent of its drinking water. water quality related to various land uses. The target During the storm of April 2-5, 2000, concentra- issues of this assessment program—nutrients, fecal- tions of several pesticides were at least a factor indicator bacteria, and pesticides—coincide with five times greater in Huntsville’s intake water assessments conducted by State water-quality regula- when compared with concentrations in the Ten- tory agencies on causes of water-quality impairment in the Flint River Basin (Tennessee Department of Envi- nessee River upstream from the Flint River, ronment and Conservation, 2000; Alabama Depart- although concentrations of all pesticides were ment of Environmental Management, 2000, below the U.S. Environmental Protection Agency table 6-17), and with concerns of the local watershed drinking-water standards at all sites on the Ten- group, the Flint River Conservation Association. The nessee River and in Huntsville’s intake water. water-quality assessments of water (designated as impaired water, 1998, in fig. 2) in the Flint River Basin by State regulatory agencies are presented in this INTRODUCTION report to add perspective to the interpretations of water-quality data collected for this study; however, The Flint River, a tributary to the Tennessee this study was not designed to address sources or River, drains 568 square miles (mi2) of primarily agri- causes of impairment in specific stream reaches. cultural land in northern Alabama and south-central Tennessee (fig. 1). Urban and residential land repre- sent a small (less than 1 percent), but growing part of Purpose and Scope land use in the watershed, as residential growth from the City of Huntsville, Alabama, spreads northward The purposes of this report are to characterize and eastward into the watershed. The Flint River is an surface-water quality in the Flint River Basin across a important recreational and scenic resource; a 34-mile range of seasonal and streamflow conditions, and to (mi) section of the river (fig. 2) is a popular canoe and assess variation of base-flow water quality in relation tubing area and was designated a canoe trail by the to land use in the Basin. The water-quality constituents Madison County Commission in 1993. Local agencies included in the characterization are pesticides, fecal- are conducting riparian restoration projects to protect indicator bacteria, and nutrients. The effect of the Flint and enhance habitat for the diverse aquatic life along River Basin on water quality in the main stem of the the Flint River. Among the several threatened species Tennessee River at a drinking-water intake for the City of fish and aquatic invertebrates found in the Basin are of Huntsville, Alabama, also is described. This report the slackwater darter, Tuscumbia darter, and southern is based on data collected from January 1999 through cave fish. May 2000 from eight stream sites in the Flint River Most of the Flint River Basin lies within the Basin and from three sites on the main stem of the eastern part of the Highland Rim Physiographic Tennessee River. 2 Water Quality of the Flint River Basin, Alabama and Tennessee, 1999-2000 10 15 MILES 10 15 20 KILOMETERS Introduction 3 4 Water Quality of the Flint River Basin, Alabama and Tennessee, 1999-2000 Acknowledgments variation of base-flow water quality in the Flint River Basin, and to relate water quality in the Flint River to The authors thank several individuals who gave water quality in a drinking-water source for the City of special assistance in compiling data: Joseph Berry and Huntsville. William Abbott, Natural Resources Conservation Ser- vice; Mark Hall, Alabama Cooperative Extension Ser- vice; David Qualls, Tennessee Agricultural Extension Design of Monitoring Program Service; Victor Payne, Alabama Soil and Water Con- The monitoring program included three separate servation Committee; and Pat Morgan, City of Hunts- networks of stream sites and sampling schedules ville. Susan F. Weber, Flint River Conservation Association, and James Kingsbury and Gregory Clark, designed to match the different study objectives (tables 1 and 2). The intensive monitoring network, USGS, provided excellent technical guidance and consisting of two sites (Hester Creek and Flint River review. Thanks to Reavis Mitchell, USGS, for assist- ing with the design of illustrations. Assistance from sites, fig. 1), was used to characterize water quality in the Flint River Basin across a range of seasonal and Wayne Miller, City of Huntsville, during a special streamflow conditions. The spatial monitoring net- storm sampling effort, is appreciated. work, consisting of the two intensive sites