What is NAWQA?

In 1991, the U.S. Geological Survey began a full-scale National Water-Quality Assessment (NAWQA) Program to address the need for consistent and scientifically sound information for managing the Nation's water resources. Compared to other national water-quality-assessment studies, this program is unique in that it integrates monitoring the quality of surface and ground waters with studying aquatic ecosystems.

Goals of the NAWQA Program are

  • Describe current water-quality conditions for a large part of the Nation's freshwater streams and aquifers (water-bearing sediments and rocks).
  • Describe how water quality is changing over time.
  • Improve the understanding of the primary natural and human factors affecting water quality.

A major design feature of the NAWQA Program is the integration of water-quality information at a wide range of spatial scales, both within and among Study Units. Assessments of this information adhere to a nationally consistent study design which allows comparisons among river basins and comprehensive national evaluations.

National Synthesis Projects include

Cycle I (1991–2001)

To assess the quality of water across the Nation, NAWQA Study Units were selected. The Study Units—59 major river and aquifer systems—represent the environmental diversity of the Nation (Map). The Study Units were divided into three groups that were studied intensively on a rotational schedule. Cycle I assessment for each group consisted of 2 years of initial planning and retrospective analysis of existing data, 3 years of intensive data collection and analysis, and 6 years of report preparation and low-level assessment activity.

In Cycle I, NAWQA focused primarily on its first goal, describing water-quality conditions. This was done through the Retrospective Analysis (a review and analysis of existing water-quality data) and the Occurrence and Distribution Assessment (intensive data collection to establish existing water-quality conditions of streams and major aquifers). Synoptic studies of sources, transport, fate, and effect were limited in scope and emphasis.

A national summary of pesticides and nutrients can be found in Circular 1225 and Fact Sheet 116-99.

Cycle II (2001–2010)

In 2001, NAWQA began its second decade of intensive water-quality assessment on 42 of the Nation's most important river-basin and aquifer systems. The original 59 Study Units of Cycle I were reduced to 42, either by elimination or combination. In aggregate, the 42 Study Units account for more than 60 percent of the Nation's water use. As part of the reorganization, the White River Basin (WHIT) and the Great and Little Miami River Basins (MIAM) were combined into the the new White River–Great and Little Miami River Basins (WHMI) Study Unit (map).

The three goals of the NAWQA Program remain the foundation of the national assessment. Less emphasis will be placed on status assessment because of the substantial advances made in assessing the water-quality conditions during Cycle I. The New Status Assessment, however, will focus on sampling geographic gaps and analyzing for selected new constituents not studied in Cycle I.

Cycle II places more emphasis on describing long-term trends and understanding human and natural factors that control water quality. Long-term trends are scheduled to be studied by resampling the stream and well sites established in Cycle I. These sites are part of the Trend Networks for Streams and Ground Water. Reservoirs are scheduled to be sampled for sediment cores as part of the Trend Network for Contaminants in Sediment. The cores provide a record of the depositional history because they contain sediment from past decades to the present. Spatial Studies of Effects of Land-Use Change on Water Quality addresses long-term trends by using spatial variability in land use to evaluate temporal changes. In addition, these studies are scheduled to look more directly at effects of urbanization- and agricultural-management practices on water quality. Factors that control water quality are scheduled to be addressed with Topical Studies that not only focus on sources, transport processes, and effects, but also on implications for water-quality management and the possibility of extrapolating to other unmonitored areas.

More information can be found in Fact Sheet 071-01 and Water Resources Impact (July 2002).