Water Quality in the Santa Ana Basin

California, 1999–2001


U.S. Geological Survey Circular 1238


By Kenneth Belitz, Scott N. Hamlin, Carmen A. Burton, Robert Kent, Ronald G. Fay, and Tyler Johnson


This circular is available as a pdf.


This report contains the major findings of a 1999–2001 assessment of water quality in the Santa Ana River Basin. It is one of a series of reports by the National Water-Quality Assessment (NAWQA) Program that present major findings in 51 major river basins and aquifer systems across the Nation.


In these reports, water quality is discussed in terms of local, State, and regional issues. Conditions in a particular basin or aquifer system are compared to conditions found elsewhere and to selected national benchmarks, such as those for drinking-water quality and the protection of aquatic organisms.


This report is intended for individuals working with water-resource issues in Federal, State, or local agencies, universities, public interest groups, or in the private sector. The information will be useful in addressing a number of current issues, such as the effects of agricultural and urban land use on water quality, human health, drinking water, source-water protection, hypoxia and excessive growth of algae and plants, pesticide registration, and monitoring and sampling strategies. This report is also for individuals who wish to know more about the quality of streams and ground water in areas near where they live and how that water quality compares to other areas across the Nation.


The water-quality conditions in the Santa Ana River Basin summarized in this report are discussed
in detail in other reports that can be accessed from sana_nawqa/. Detailed technical information, data and analyses, collection and analytical methodology, models, graphs, and maps that support the findings presented in this report in addition to other reports in this series from other basins can be accessed from the national NAWQA Web site (


National Water-Quality Assessment Program

What kind of water-quality information does the NAWQA Program provide?

Introduction to this Report

Summary of Major Findings

Stream and River Highlights

Ground-Water Highlights

Introduction to the Santa Ana Basin

The hydrologic cycle in the Santa Ana Basin is dominated by human activities

Water quality in the Santa Ana Basin reflects the influence of urbanization

Major Findings

Concentrations of nitrate and dissolved solids are elevated in surface water
and ground water in the Santa Ana Basin

Nitrate and dissolved-solids concentrations in streams are related to
water source and location

Nitrate and dissolved-solids concentrations are higher in ground water
recharged since the 1950s than in older ground water

Pesticides and volatile organic compounds are commonly present in surface
water and ground water

Some pesticides are detected more frequently in streams, and at higher concentrations, during and after storms than during dry periods

Volatile organic compounds in Santa Ana Basin streams can come from the air,
treated wastewater, or ground water or can be washed in by storms

Pesticides and volatile organic compounds are more frequently detected in
ground water recharged since the 1950s than in older ground water

Organochlorine and semivolatile organic compounds are detected more frequently
in bed sediment and fish tissue at urban sites than at undeveloped sites

Detection frequencies of organic compounds at Santa Ana River sites are different
than detection frequencies at tributary sites

Sediment cores from reservoir and retention basins provide a historical record of
pesticides and semivolatile organic compounds

Trace-element concentrations sometimes exceed aquatic-life guidelines in
bed sediment and reservoir-sediment cores

Urbanization has altered stream channels and the sources of water reaching
stream channels; these changes have degraded aquatic ecosystems

Today’s surface water is tomorrow’s ground water

Study Unit Design

Stream Chemistry

Aquatic Ecology and Sediment

Ground-Water Quality

References Cited


Appendix—Water Quality Data from the Santa Ana Basin in a National Context

Points of Contact and Additional Information


The companion Web site for NAWQA summary reports:


Santa Ana Basin contact and Web site:

USGS State Representative

U.S. Geological Survey

Water Resources Discipline

5735 Kearny Villa Road, Suite O

San Diego, CA 92123



National NAWQA Program:

Chief, NAWQA Program
U.S. Geological Survey
Water Resources Discipline
12201 Sunrise Valley Drive, M.S. 413
Reston, VA 20192


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U.S. Geological Survey,

Information Services
Box 25286, Denver Federal Center
Denver, CO 80225


For more information about the USGS and its products:

Telephone: 1-888-ASK-USGS
World Wide Web:


The text and graphics are presented here in pdf format (print quality). The full report is 23.9MB.


If you have Adobe® Acrobat® or Adobe® Acrobat® Reader® installed on your computer, you may view and print the PDF version of this report. Acrobat Reader, is a free download it from Adobe Systems, Inc.  Users with disabilities can view information concerning accessibility at


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