Geological Survey (USGS) is committed to serve the Nation with accurate and
timely scientific information that helps enhance and protect the overall quality
of life, and facilitates effective management of water, biological, energy, and
mineral resources. (http://www.usgs.gov/).
Information on the quality of the Nation’s water resources is of critical
interest to the USGS because it is so integrally linked to the long-term
availability of water that is clean and safe for drinking and recreation and
that is suitable for industry, irrigation, and habitat for fish and wildlife.
Escalating population growth and increasing demands for the multiple water uses
make water availability, now measured in terms of quantity and quality, even
more critical to the long-term sustainability of our communities and ecosystems.
The USGS implemented the National Water-Quality Assessment (NAWQA) Program to
support national, regional, and local information needs and decisions related to
water-quality management and policy. (http://water.usgs.gov/nawqa). Shaped by
and coordinated with ongoing efforts of other Federal, State, and local
agencies, the NAWQA Program is designed to answer: What is the condition of our
Nation’s streams and ground water? How are the conditions changing over time?
How do natural features and human activities affect the quality of streams and
ground water, and where are those effects most pronounced? By combining
information on water chemistry, physical characteristics, stream habitat, and
aquatic life, the NAWQA Program aims to provide science-based insights for
current and emerging water issues and priorities. NAWQA results can contribute
to informed decisions that result in practical and effective water-resource
management and strategies that protect and restore water quality.
Since 1991, the NAWQA Program has implemented interdisciplinary assessments
in more than 50 of the Nation’s most important river basins and aquifers,
referred to as Study Units. (http://water.usgs.gov/nawqa/nawqamap.html).
Collectively, these Study Units account for more than 60 percent of the overall
water use and population served by public water supply, and are representative
of the Nation’s major hydrologic landscapes, priority ecological resources, and
agricultural, urban, and natural sources of contamination.
Each assessment is guided by a nationally consistent study design and methods
of sampling and analysis. The assessments thereby build local knowledge about
water-quality issues and trends in a particular stream or aquifer while
providing an understanding of how and why water quality varies regionally and
nationally. The consistent, multi-scale approach helps to determine if certain
types of water-quality issues are isolated or pervasive, and allows direct
comparisons of how human activities and natural processes affect water quality
and ecological health in the Nation’s diverse geographic and environmental
settings. Comprehensive assessments on pesticides, nutrients, volatile organic
compounds, trace metals, and aquatic ecology are developed at the national scale
through comparative analysis of the Study-Unit findings. (http://water.usgs.gov/nawqa/natsyn.html).
The USGS places high value on the communication and dissemination of
credible, timely, and relevant science so that the most recent and available
knowledge about water resources can be applied in management and policy
decisions. We hope this NAWQA publication will provide you the needed insights
and information to meet your needs, and thereby foster increased awareness and
involvement in the protection and restoration of our Nation’s waters.
The NAWQA Program recognizes that a national assessment by a single program
cannot address all water-resource issues of interest. External coordination at
all levels is critical for a fully integrated understanding of watersheds and
for cost-effective management, regulation, and conservation of our Nation’s
water resources. The Program, therefore, depends extensively on the advice,
cooperation, and information from other Federal, State, interstate, Tribal, and
local agencies, non-government organizations, industry, academia, and other
stakeholder groups. The assistance and suggestions of all are greatly
Robert M. Hirsch,
Associate Director for Water