USGS - New England Coastal Basins

NEW ENGLAND COASTAL BASINS NAWQA PROGRAM:

WHAT IS THE NATIONAL WATER-QUALITY ASSESSMENT (NAWQA) PROGRAM?

Robert M. Hirsch, Chief Hydrologist, Water Resources Division

USGS Mission
NAWQA Program Objectives
NAWQA Design Components: Surface Water, Ground Water, Ecology

The mission of the U.S. Geological Survey (USGS) is to assess the quantity and quality of the earth resources of the nation and to provide information that will assist resource managers and policy makers at federal, state, and local levels in making sound decisions. Assessment of water quality conditions and trends is an important part of this overall mission. One of the greatest challenges faced by water resources scientists is acquiring reliable information that will guide the use and protection of the nation's water resources. That challenge is being addressed by federal, state, interstate, and local water resource agencies and by many academic institutions. These organizations are collecting water quality data for a host of purposes that include compliance with permits and water supply standards; development of remediation plans for a specific contamination problem; operational decisions on industrial, wastewater, or water supply facilities; and research on factors that affect water quality.

An additional need for water quality information is to provide a basis on which regional and national level policy decisions can be based. Wise decisions must be based on sound information. As a society we need to know whether certain types of water quality problems are isolated or ubiquitous, whether there are significant differences in conditions among regions, whether the conditions are changing over time, and why these conditions change from place to place and over time. The information can be used to help determine the efficacy of existing water quality policies and to help analysts determine the need for, and likely consequences of new policies. To address this, Congress appropriated funds in 1986 for the USGS to begin a pilot program in seven project areas to develop and refine the National Water-Quality Assessment Program. (NAWQA). In 1991, the USGS began full implementation of the program. The NAWQA Program builds upon a an existing base of water quality studies of the USGS, as well as those of other federal, state, and local agencies.

The objectives of the NAWQA program are to:

Describe the current water quality conditions for a large part of the nation's freshwater streams, rivers, and aquifers.

Describe how water quality is changing over time.

Improve understanding of the primary natural and human factors that affect water quality conditions.

This information will help support the development and evaluation of management, regulatory, and monitoring decisions by other federal, state, and local agencies to protect, use and enhance water resources.

The goals of the NAWQA program are being achieved through ongoing and proposed investigations of the nation's most important river basins and aquifer systems, which are referred to as study units. These 59 study units are distributed throughout the nation and cover a diversity of hydrogeologic settings. More than two thirds of the nation's freshwater use occurs within the 59 study units and more than two thirds of the people served by public water supply systems live within their boundaries. National synthesis of data analysis, based on aggregation of comparable information obtained from the study units, is a major component of the program.

This effort focuses on selected water quality topics using nationally consistent information. Comparative studies will explain differences and similarities in observed water quality conditions among study areas and will identify changes and trends and their causes. The first topics addressed by the national synthesis are pesticides, nutrients, volatile organic compounds, and aquatic biology. Discussions on these and other water quality topics will be published in periodic summaries of the quality of the nation's ground and surface water as the information becomes available.

The NAWQA program depends heavily on the advice, cooperation, and information from many federal, state, interstate, tribal, and local agencies and the public. The assistance and suggestions of all are greatly appreciated.

Design Components of NAWQA

Surface Water

The national study design for surface waters focuses on water quality conditions in streams using three interrelated components-water-column studies, bed sediment and fish tissue studies, and ecological studies. Water column studies monitor physical and chemical characteristics, which include suspended sediment, major ions, nutrients, organic carbon, and dissolved pesticides, and their relation to hydrologic conditions, sources, and transport. Most surface water is monitored at sites termed either basic fixed sites or intensive fixed sites, according to the frequency of the sampling. The sampling sites are selected to determine the quality of water in relation to important environmental settings in the study unit. Most NAWQA study units have 8-10 basic fixed and 2-3 intensive fixed sites. Basic fixed sites are sampled monthly and at high flows for 2 years of the 3 year high intensity phase. The intensive fixed sites are monitored more frequently (as often as weekly during key time periods) for at least 1 year, to characterize short-term variations of water quality. Basic fixed or intensive fixed sites can be either indicator or integrator sites. Indicator sites represent relatively homogeneous, small basins (less than 100 square miles) associated with specific environmental settings, such as a particular land use that substantially affects water quality in the study unit. Integrator sites are established at downstream points in large (thousands of square miles) relatively heterogeneous drainage basins with complex combinations of land use settings. Indicator sites are typically located in the drainage basins of integrator sites. Water samples are also collected as part of synoptic (short term) investigations of specific water quality conditions or issues during a specific hydrologic period (for example during low streamflow) to provide greater spatial coverage and to allow investigators to assess whether the basic fixed or intensive fixed sites are representative of streams throughout the study unit. Bed sediment and fish tissue studies assess trace elements and hydrophobic organic contaminants at 15-30 sites to determine their occurrence and distribution in the study unit. Ecological studies evaluate the relations among physical, chemical, and biological characteristics of streams. Aquatic biological communities at the basic- and intensive fixed sites are surveyed during the 3 years of the high intensity sampling phase. These surveys are done along a delineated stream reach and include a habitat assessment of the site and annual surveys of the fish, algal, and benthic invertebrate communities. Additionally, ecological sampling may be integrated with surface water synoptic studies to provide greater spatial coverage and to assess whether the biological communities at basic- and intensive fixed sites are representative of streams throughout the study unit.

Ground Water

The national study design for ground water focuses on water quality conditions in major aquifers, with emphasis on recently recharged ground water associated with present and recent human activities, by using study unit surveys, land use studies, and flowpath studies. Ground-water samples are analyzed for major ions, nutrients, pesticides, volatile organic compounds, and trace elements. Study unit surveys are used to assess the water quality of the major aquifer systems of each study unit. About 20-30 existing wells are randomly selected to be sampled in each of 2-3 aquifer subunits. Land use studies focus on recently recharged shallow aquifer systems so that the influences of land use practices and natural conditions can be assessed.

Typically, about 20-30 new observation wells are randomly located within each land use and aquifer type. Results from the 2-4 land use studies typically performed can be compared with results from the general study unit survey to determine the effect of particular land uses on ground-water quality. Flowpath studies use transects and groups of clustered, multilevel observation wells to examine specific relations among land use practices; ground-water flow; and contaminant occurrence, transport, and interactions between ground and surface water.

Ecology

Ecological studies are conducted along with the surface water and ground water sampling activities. Aquatic biological communities are surveyed at the basic and intensive fixed sites during the three years of the high intensity sampling phase. These investigations are conducted along a delineated stream reach and include a habitat assessment of the site and annual surveys of the fish, algal, and benthic invertebrate communities.

This approach is intended to provide insight into ecological variability over time, the role that water quality plays in community structure and stability, and differences with respect to various environmental settings. Additionally, studies are conducted to provide overviews of the ecological status of the study unit. Ecological synoptic studies are conducted within a network of sites to evaluate spatial variability of biological communities or to address issues of special concern within the study unit.

U.S. Department of the Interior
U.S. Geological Survey
New Hampshire/Vermont District, USGS, 361 Commerce Way, Pembroke, NH 03275, USA
Comments and feedback: NH/VT webmaster-nh@usgs.gov
Last Updated February 20, 2007
Privacy Statement || Disclaimer

NEW ENGLAND COASTAL BASINS NAWQA PROGRAM:

Design Components of NAWQA

Surface Water

Ground Water

Ecology