Water Quality in the Acadian-Pontchartrain

Louisiana and Mississippi, 1999–2001

U.S. Geological Survey Circular 1232

By Dennis K. Demcheck, Roland W. Tollett, Scott V. Mize, Stanley C. Skrobialowski, Robert B. Fendick, Jr., Christopher M. Swarzenski, and Stephen Porter

This circular is available as a pdf.


This report contains the major findings of a 19992001 assessment of water quality in the Acadian-Pontchartrain Drainages Study Unit. 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 also is 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 Acadian-Pontchartrain Drainages Study Unit summarized in this report are discussed in detail in other reports that can be accessed from ( 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 Acadian-Pontchartrain Drainages

Land use affects water quality

Water Use in Louisiana

Hydrologic Conditions and Their Effects on Water Quality

Ground Water

Major Findings

Surface Water


Pesticides compounds vary with land use

Pesticides occur in mixtures and as degradation products

Pesticides vary seasonally in streams

Mississippi River hydrology affects occurrence of atrazine in streams and rivers


Nutrient concentrations differ with land use

Forms of nitrogen vary among streams in the Acadian-Pontchartrain Drainages
and in the Mississippi River at St. Francisville

Nutrient concentrations vary seasonally in streams

Organochlorine compounds persist in sediment and fish tissue

Elevated levels of mercury are present in fish north of Lake Pontchartrain

Aquatic communities are affected by land use and habitat

Ground Water

Nitrate, Pesticides, and Volatile Organic Compounds

Naturally Occurring Trace Elements and Water Chemistry


Study-Unit Design

Stream-Chemistry and Ecology

Ground Water

References Cited


Appendix—Water Quality Data from the Acadian-Pontchartrain Drainages in a
National Context

Points of Contact and Additional Information

The companion Web site for NAWQA summary reports:

Acadian-Pontchartrain Drainages contact and web site:

USGS State Representative
U.S. Geological Survey
Water Resources Discipline
3535 South Sherwood Forest Blvd., Suite 120
Baton Rouge, Louisiana 70816


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 15.6MB.

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