Lower Tennessee River (LTEN) Basin Study

Science Center Objects

Welcome....the Lower Tennessee River Basin in Tennessee, Alabama, Georgia, Kentucky, and Mississippi is one of the 59 study units that are part of the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program.The long-term goals of this program are to describe the status and trends in the quality of a large, representative part of the Nation's surface- and ground-water resources, and to provide a sound, scientific understanding of the primary factors affecting the quality of these resources.

National Water-Quality Assessment (NAWQA) Program
Lower Tennessee River Basin


During the past 25 years, industry and government made large financial investments that have resulted in improved water quality across the Nation; however, many water-quality concerns remain. The U.S. Geological Survey began a full-scale National Water-Quality Assessment (NAWQA) Program in 1991 to provide consistent and scientifically sound information for managing the Nation's water resources. This program is unique compared to other national water-quality assessment studies in that it integrates the monitoring of the quality of surface and ground waters with the study of aquatic ecosystems. The goals of the NAWQA Program are (1) to describe current water-quality conditions for a large part of the Nation's freshwater streams and aquifers (water-bearing sediments and rocks), (2) to describe how water quality is changing over time, and (3) to improve our understanding of the primary natural and human factors affecting water quality.


The goals of the NAWQA program are being achieved through ongoing or planned investigations of 59 of the Nation's most important river and aquifer systems, which are referred to as study units. These study units were selected to represent the diverse geography, water resources, and land and water uses of the Nation. The Lower Tennessee River Basin is one such study unit, encompassing the drainage area between Chattanooga, Tennessee, and Paducah, Kentucky. The U.S. Geological Survey began the Lower Tennessee River Basin NAWQA study in 1996.


Communication and coordination between the U.S. Geological Survey and other scientific and land- and water-management organizations are critical components of the NAWQA Program. Each study unit maintains a liaison committee consisting of representatives from Federal, State, and local agencies, universities, the private sector, watershed organizations, and others who have water-resource responsibilities and interests. Activities include the exchange of information about regional and local water-quality issues, identification of sources of data and information, assistance in the design and scope of study products, and the review of study planning documents and reports. The liaison committee for the Lower Tennessee River Basin study met for the first time in November 1997.

The overall success of the Lower Tennessee River Basin NAWQA study will depend on the advice, cooperation, and information from many Federal, State, regional, and local agencies, and the public concerned about water resources in the basin. The assistance and suggestions of all are welcome.


he Lower Tennessee River Basin study is one of 14 NAWQA studies that began in Federal fiscal year 1997 (October 1996). Study planning and design, and analysis of existing data will be done during the first 2 years. After the 2-year planning period, surface- and ground-water and ecological data will be collected intensively for 3 years during a high-intensity phase. A lower intensity phase follows for the next 6 years during which water qual- ity is monitored at a selected number of sites and areas assessed during the high-intensity phase. Alternating high- and low-intensity monitoring phases allows the NAWQA Program to examine trends in water quality over time in a cost-effective manner, eventually assessing about two-thirds of the Nation's water resources.

During the planning period, existing data and results from previous studies will be reviewed to identify gaps in the current data and to help understand the primary physical, chemical, and ecological factors that affect water quality in the study unit. Information obtained from review of previous studies, along with reconnaissance of existing monitoring stations and candidate sampling sites, will be used to design a sampling program for the study unit.

During the high-intensity phase, new chemical, physical, and ecological data will be collected from selected areas at local and regional scales to describe the quality of water throughout the study unit. These data will be used to determine the water chemistry of streams and aquifers; the quantity and quality of suspended sediment and bottom sediments in streams; the variety and number of fish, benthic invertebrates, and algae in streams; and the presence of contaminants in fish tissues. Individual streams, aquifers, and biological species representative of the most important water resources and water-quality concerns in the study unit and the Nation are selected for sampling and analysis. A series of technical and nontechnical reports describing the results of high- and low-intensity-phase data collection and analysis are planned.


The NAWQA Program is designed to assess the status of and trends in the quality of the Nation's ground- and surface-water resources and to link the status and trends with an understanding of the natural and human factors that affect the quality of water. Consistent data collection and assessment methods in all NAWQA studies make this possible and are critical for providing uniform and comparable information on water quality for the Nation. Surface-water, ecological, and ground-water studies are done at local (a few square miles to hundreds of square miles) and regional (thousands of square miles) scales to help understand water-quality conditions and issues in a study unit. NAWQA study-unit data collected using this multiscale, interdisciplinary approach will be aggregated to provide national-scale water-quality assessments. Partnerships and cooperative studies between local, State, and Federal agencies can be developed to help meet specific needs. The basic design described in the following sections is similar among NAWQA study units nationwide.


Ecological studies in conjunction with surface-water sampling activities are conducted to provide insight into ecological variability over time, relations between water quality and community structure and stability, and ecological differences with respect to various environmental settings. Aquatic biological communities are surveyed at basic- and intensive-fixed sites during the 3-year high-intensity phase. These investigations are conducted along delineated stream reaches and include aquatic and riparian habitat assessments and annual surveys of fish, algal, and benthic invertebrate communities. Trace elements and synthetic organic compounds are analyzed in bed sediment and fish tissue at selected sites to determine their occur- rence and distribution and relation to land use and environmental setting. Ecological synoptic studies are conducted to evaluate spatial variability of biological communities or address issues of special concern within the study unit.