National Water-Quality Assessment (NAWQA) Program

Science Center Objects

During the past 25 years, industry and government made large financial investments in pollution control that have resulted in better water quality across the Nation; however, many water-quality problems remain. To address the need for consistent and scientifically sound information for managing the Nation's water resources the U.S. Geological Survey began a full-scale National Water-Quality Assessment (NAWQA) Program in 1991. This program is unique compared to other national water-quality assessment studies in that it integrates the monitoring of the quality surface and ground-waters with the study of aquatic ecosystems.

The goals of the NAWQA Program are to:

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

Assessing the quality of water in every location of the Nation would not be practical; therefore, NAWQA studies are conducted within areas called study units. These study units are composed of 59 major river and aquifer systems that reflect the environmental diversity of the Nation (Map).

The following links are to regional web pages from the NAWQA program. 

Sacramento River Basin National Water-Quality Assessment (NAWQA) Program

Beginning in October 2004, and continuing for a period of 4 years, the NAWQA Program will again intensively investigate the quality of water resources in the Sacramento River Basin, as part of the second decadal cycle of the program. While the long term goals remain the same, the emphasis of these renewed investigations will shift from status of water quality to trends in water quality and understanding of natural and anthropogenic factors affecting water quality.

Santa Ana Basin National Water-Quality Assessment (NAWQA) Program

The Santa Ana Basin study is one of several NAWQA studies that began in 1997. Study planning and analysis of existing data was done during the first 2 years of the study. After the 2-year planning period, surface- and ground-water and biological data were collected intensively for 3 years (termed the high-intensity phase). A low-intensity phase lasting 6 years began in 2002, during which water quality is monitored at a limited number of sites and areas that were sampled during the high-intensity phase. This combination of high- and low-intensity monitoring phases allows the NAWQA Program to examine long-term trends in water quality and aquatic ecology. A series of technical and non-technical reports will describe and summarize results of high- and low-intensity data collection.