Water Quality in the Cook Inlet Basin Alaska, 1998–2001

Circular 1240


By Roy L. Glass, Timothy P. Brabets, Steven A. Frenzel, Matthew S. Whitman, and Robert T. Ourso


This circular is available as a pdf.


This report contains the major findings of a 1998–2001 assessment of water quality in the Cook Inlet 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 the quality of water in other areas across the Nation.


The water-quality conditions in the Cook Inlet Basin summarized in this report are discussed in detail in other reports that can be accessed at 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 reports in this series from other basins, can be accessed from the national NAWQA Web site (




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



Stream and River Highlights

Ground-Water Highlights


Diverse topography results in diverse climate and hydrology

Most of the basin is undeveloped

Human activities affect water quality and aquatic biota

Most drinking water comes from rivers and streams

Results from this study provide a benchmark for measuring changes to come


Water quality in streams and rivers in the Cook Inlet Basin is affected by natural features and human activities

Pesticides detected in an urban stream in Anchorage also were detected in urban streams throughout the Nation

Many volatile organic compounds were present in an urban stream in Anchorage at low concentrations

Nitrate concentrations were low in streams, but phosphorus commonly exceeded criteria for preventing nuisance plant growth

Concentrations of dissolved organic carbon were highest in streams draining wetlands

Urban streams are contaminated by fecal-indicator bacteria

Streams and rivers in the Cook Inlet Basin are colder than other rivers nationally

Some streambed and lakebed sediments in Cook Inlet Basin are contaminated by trace elements and organic compounds

Trace elements are present at naturally large concentrations in streambed sediments

Concentrations of lead in lakebed sediments have decreased since the 1970s

Chemically persistent organic contaminants were detected in urban lakebed sediments but were detected only infrequently in streambed sediments or fish tissues

Semivolatile organic compounds were detected infrequently in streambed sediments

Aquatic communities are adversely affected by a variety of natural and human-induced stresses

Degradation of water quality and stream ecosystems occurs early in the process of watershed urbanization

Natural and human factors affect ground-water quality

Low levels of pesticides and volatile organic compounds were detected in ground water

Concentrations of nutrients in ground water were low

Concentrations of radon in ground water are a health concern

Arsenic in ground water is a national concern




APPENDIX—Water-Quality Data from the Cook Inlet Basin in a National Context

Points of Contact and Additional Information


The companion Web site for NAWQA summary reports:


Cook Inlet Basin contact and Web site:

Chief, Water Resources Office

U.S. Geological Survey

Alaska Science Center

4230 University Drive,

Suite 201

Anchorage, AK 99508



National NAWQA Program:

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


For sale by


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 full report is available in pdf format and is 17.8 MB in size.


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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