0

Front cover photographs

Upper left: Close-up of Panicum hemitomon floating marsh, Jean Lafitte National Historical Park 

and Preserve, Louisiana 

(Photograph by author)

Center: Orchid growing in floating marsh, Jean Lafitte National Historical Park and Preserve, 

Louisiana

(Photograph by Thomas Hargis, Coastal Monitoring, Inc.)

Lower right: Pipeline Canal near Segnette Waterway, Jean Lafitte National Historical Park and 

Preserve, Louisiana

(Photograph by author)
i

RESURVEY OF QUALITY OF SURFACE WATER 

AND BOTTOM MATERIAL OF THE BARATARIA 

PRESERVE OF JEAN LAFITTE NATIONAL 

HISTORICAL PARK AND PRESERVE, 

LOUISIANA, 1999-2000

By Christopher M. Swarzenski

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 03-4038

Prepared in cooperation with the 

NATIONAL PARK SERVICE 

Baton Rouge, Louisiana

2004
ii

U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

The use of trade, product, industry, or firm names in this report is for descriptive or location purposes only and does not 

constitute endorsement of products by the U.S. Government nor impute responsibility for any present or potential 

effects on the natural resources.

_____________________________________________________________________________________

For additional information contact: Copies of this report can be purchased from:

District Chief U.S. Geological Survey

U.S. Geological Survey Branch of Information Services

3535 S. Sherwood Forest Blvd., Suite 120 Box 25286

Baton Rouge, LA 70816 Denver, CO 80225

E-mail: dc_la@usgs.gov E-mail: infoservices@usgs.gov

Fax: (225) 298-5490 Fax: (303) 202-4693

Telephone: (225) 298-5481 Telephone (toll free): 1-888-ASK-USGS

Home Page: http://la.water.usgs.gov
iii

CONTENTS

Abstract.......................................................................................................................................................... 1

Introduction ................................................................................................................................................... 2

Purpose and Scope........................................................................................................................... 4

Description of Study Area ............................................................................................................... 4

Approach and Methods.................................................................................................................... 4

Organic Compounds and Trace Elements............................................................................... 4

Nutrients and Major Inorganic Ions........................................................................................ 6

Acknowledgments........................................................................................................................... 7

Quality of Surface Water and Bottom Material, 1999-2000.......................................................................... 7

Surface Water................................................................................................................................... 9

Bottom Material............................................................................................................................. 17

Comparison Between 1981-82 and 1999-2000 Surveys ............................................................................. 17

Surface Water................................................................................................................................. 18

Bottom Material............................................................................................................................. 24

Summary and Conclusions.......................................................................................................................... 26

References ................................................................................................................................................... 27

FIGURES

 1. Map showing location of the Barataria Preserve, Jean Lafitte National Historical 

Park and Preserve, Louisiana .............................................................................................................. 3

 2. Map showing sampling sites in the Barataria Preserve, Jean Lafitte National 

Historical Park and Preserve, Louisiana ............................................................................................. 5

 3-8. Graphs showing:

 3. Specific conductance in surface water of the Barataria Preserve, Jean Lafitte 

National Historical Park and Preserve, Louisiana, March 1999 to April 2000 .................................. 8

 4. Dissolved orthophosphate, ammonia, and organic nitrogen concentrations in

surface water of the Barataria Preserve, Jean Lafitte National Historical 

Park and Preserve, Louisiana, March 1999 to May 2000 ................................................................. 13

 5. Dissolved calcium, magnesium, and potassium concentrations in surface water 

of the Barataria Preserve, Jean Lafitte National Historical Park and Preserve, 

Louisiana, March 1999 to May 2000................................................................................................ 15

6. Dissolved sulfate and chloride concentrations in surface water of the Barataria 

Preserve, Jean Lafitte National Historical Park and Preserve, Louisiana, 

March 1999 to May 2000................................................................................................................ 16

 7. Ratio of dissolved calcium to magnesium in the Mississippi River and surface 

water of the Barataria Preserve, Jean Lafitte National Historical Park and

Preserve, Louisiana, 1999-2000...................................................................................................... 18

8. Specific conductance at Bayou Segnette near Barataria, April 1981 to March 1982, 

and Segnette Waterway west of Crown Point, March 1999 to April 2000 ..................................... 20

9-11. Graphs summarizing:

9. Dissolved nitrite+nitrate, ammonia, and organic nitrogen concentrations in surface 

water of the Barataria Preserve, Jean Lafitte National Historical Park and Preserve, 

Louisiana, March 1981 to March 1982 and March 1999 to May 2000 .......................................... 21
iv

10. Dissolved calcium, magnesium, and potassium concentrations in surface water of the

Barataria Preserve, Jean Lafitte National Historical Park and Preserve, Louisiana, 

March 1981 to March 1982 and March 1999 to May 2000............................................................. 22

11. Dissolved sulfate and chloride concentrations in surface water of the Barataria Preserve,

Jean Lafitte National Historical Park and Preserve, Louisiana, March 1981 to

March 1982 and March 1999 to May 2000...................................................................................... 23

TABLES

 1. Whole-water (total recoverable) pesticide and polychlorinated biphenyl concentrations in surface water of the Barataria Preserve, Jean Lafitte National 

Historical Park and Preserve, Louisiana, August 1999 to May 2000 ............................................. 10

 2. Whole-water (total recoverable) and dissolved trace-element, iron, and manganese

concentrations in surface water of the Barataria Preserve, Jean Lafitte 

National Historical Park and Preserve, Louisiana, August 1999 to May 2000 .............................. 11

 3. Concentrations of dissolved nutrients in surface water of the Barataria Preserve, 

Jean Lafitte National Historical Park and Preserve, Louisiana, March 1999 to 

May 2000 ........................................................................................................................................ 12

 4. Concentrations of dissolved inorganic ions in surface water of the Barataria

Preserve, Jean Lafitte National Historical Park and Preserve, Louisiana,

March 1999 to May 2000................................................................................................................ 14

 5. Pesticide and polychlorinated biphenyl concentrations in bottom material of the 

Barataria Preserve, Jean Lafitte National Historical Park and Preserve,

Louisiana......................................................................................................................................... 19

 6. Trace-element, iron, and manganese concentrations in bottom material of the 

Barataria Preserve, Jean Lafitte National Historical Park and Preserve,

Louisiana......................................................................................................................................... 20

 7. Comparison of organic compound and trace-element concentrations in bottom 

material between the 1981-82 and 1999-2000 water-quality surveys at sites of the 

Barataria Preserve, Jean Lafitte National Historical Park and Preserve, Louisiana ....................... 25
1

ABSTRACT

The quality of water and bottom material in 

the Barataria Preserve of Jean Lafitte National 

Historical Park and Preserve, Louisiana, was surveyed from March 1999 to May 2000. Organochlorine, chlorophenoxy acid, and 

organophosphorus pesticides; polychlorinated 

biphenyls (PCB’s); and trace elements were analyzed in surface water and bottom material from 

three sites previously sampled in a 1981-82 survey. Surface water at six sites was sampled and 

analyzed for selected nutrients and major inorganic ions based on their importance to human 

health, the health of the marshes of the Barataria 

Preserve, or their usefulness in tracking the circulation of Mississippi River water in the Barataria 

Preserve. 

Southern Louisiana was in a moderate to 

severe drought during most of the sampling 

period, which elevated salinity in the Barataria 

Preserve for at least 8 months. Specific conductance values were less than 3,000 μS/cm (microsiemens per centimeter at 25 degrees Celsius) in 

surface water throughout the Barataria Preserve 

from March through September 1999. Specific 

conductance values increased over the next 2 

months and then remained between 5,000 and 

6,000 μS/cm. 

The herbicide 2,4-D was detected in water 

at the two sites sampled in August 1999 but not at 

any site during the two other sampling times. 

Iron, manganese, and the trace elements copper, 

nickel, and zinc were detected in dissolved and 

whole-water samples at all three sites. Nitrite+ 

nitrate, as nitrogen, concentrations ranged from 

less than 0.002 to 0.19 mg/L (milligrams per 

liter). Ammonia, as nitrogen, concentrations 

ranged from less than 0.01 to 0.16 mg/L. Orthophosphate, as phosphorus, concentrations ranged 

from less than 0.002 to 0.14 mg/L. Calcium, 

magnesium, potassium, sulfate, and chloride concentrations in surface water were elevated due to 

the marine influence on the composition of surface water in the Barataria Preserve during the 

sampling period. Sulfate and chloride concentrations reached 379 and 2,830 mg/L, respectively.

 Polychlorinated biphenyls, chlordane, and 

DDT were detected in bottom material. Trace 

elements were detected in bottom material at all 

three of the sampled sites. Arsenic concentrations ranged from 4 to 9 μg/g (micrograms per 

gram) and lead concentrations from 20 to 

31 μg/g. Mercury concentrations also were above 

laboratory reporting levels (LRL’s) for bottom 

material at all three sites. 

The herbicide 2,4-D was detected in surface water during both surveys. Other organic 

compounds were not detected in surface water. 

Mercury and chromium were detected in surface 

water at all three sites during the 1981-82 survey 

but were below LRL’s during the 1999-2000 survey.

Changes in chemical characteristics of bottom material occurred during the years between 

the 1981-82 and 1999-2000 surveys. DDT 

decreased in the bottom material at Bayou Segnette near Barataria. DDE, a degradation product, increased at this site, indicating that over 

RESURVEY OF QUALITY OF SURFACE WATER 

AND BOTTOM MATERIAL OF THE BARATARIA 

PRESERVE OF JEAN LAFITTE NATIONAL 

HISTORICAL PARK AND PRESERVE,

LOUISIANA, 1999-2000

By Christopher M. Swarzenski
2

time, DDT concentrations are decreasing in bottom material. PCB’s were present in similar concentrations (Bayou Segnette near Barataria) or 

increased (Bayou Segnette 4.6 miles below 

Westwego) from 1981-82 to 1999-2000. 

Cadmium concentrations consistently 

decreased by half or more at all three sites from 

1981-82 to 1999-2000. Mercury concentrations 

were consistently lower at all three sites in the 

1999-2000 survey, but the differences from the 

1981-82 survey were small. Chromium concentrations increased at two of the three sites from 

1981-82 to the present survey. At the third site, 

no chromium value was available for the earlier 

survey. Concentrations of copper and nickel 

increased in bottom material at the two sites on 

Bayou Segnette, but decreased at Kenta Canal 

northwest of Westwego. 

Probable Effects Levels (PEL’s) and 

Interim Sediment Quality Guidelines (ISQG’s) 

concentrations, as tabulated by the Canadian 

Council of Ministers of the Environment, were 

used to assess the probability of biological 

impairment in the Barataria Preserve. PEL’s are 

concentrations of a chemical at or above which 

some biological impairment is likely. ISQG concentrations are those at or below which biological impairment is unlikely. Concentrations of 

2,4-D and trace elements, when detected in surface water, were substantially lower than levels at 

which biological impairment could be expected. 

Concentrations of organic compounds in bottom 

material were at most less than 25 percent of 

PEL’s, and usually much lower. Arsenic, cadmium, copper, and lead concentrations in bottom 

material were generally slightly above or lower 

than ISQG concentrations in both surveys, 

although arsenic was as high as 53 percent of 

PEL’s at one site in the 1999-2000 survey. All 

other trace elements in bottom material were 

present in concentrations lower than ISQG concentrations.

INTRODUCTION

The Barataria Preserve of Jean Lafitte 

National Historical Park and Preserve is located 

about 10 mi (miles) southwest of New Orleans, 

Louisiana (fig. 1). The proximity of the preserve 

to a large metropolitan area and the easy access to 

water make it a popular fishing and boating area. 

Regularly updated information on water quality in 

the preserve is needed to safeguard both the 

health of those visitors who use the waterways 

and that of the Preserve’s aquatic resources. The 

most recent survey of surface-water and bottommaterial quality of the Barataria Preserve was 

done during 1981-82 (Garrison, 1982). 

Many natural and anthropogenic forces 

affect water quality of the Barataria Preserve 

(Garrison, 1982). During 1981-82, the U.S. Geological Survey (USGS) analyzed physical and 

biological properties and chemical constituents of 

surface water and bottom material at six sites 

within the Barataria Preserve (Garrison, 1982). 

The analyses included major inorganic ions and 

related physical and chemical characteristics, 

trace elements, nutrients, pesticides, and polychlorinated biphenyls (PCB’s). Data from the survey 

indicated that water from several sources was 

entering the survey area, including Lake Salvador, Segnette Waterway, Bayou Villars, and fresh 

stormwater runoff from suburban areas. Segnette 

Waterway and Bayou Villars are located at the 

southern end of the Barataria Preserve. Water 

from Lake Salvador and Bayou Villars occasionally becomes elevated in salinity with maximum 

concentrations reaching 8 ppt (parts per thousand) (Swarzenski, 1992).

By January 2003, water from a new source 

will be influencing water quality of the Barataria 

Preserve. Mississippi River water will be introduced through the Davis Pond Freshwater Diversion structure into Lake Cataouatche, about 5 mi 

northwest of the preserve. Water will be diverted 

from the Mississippi River primarily from January through June. Because of the magnitude of 

the design flow for the diversion (as much as 

10,650 cubic feet per second) (U.S. Army Corps 

of Engineers, 1998) and the proximity to the 

Barataria Preserve, water from the diversion probably will dominate the preserve during the periods the diversion is operating. Currently (2000), 

little if any water from the Mississippi River 

enters the preserve.

In 1999, the USGS, in cooperation with the 

National Park Service, began a survey of the quality of surface water and bottom material of the 

Barataria Preserve. The goal of the survey was to 

characterize current conditions of the Barataria 

Preserve and to determine whether changes had 

occurred since the 1981-82 survey. 

4

Purpose and Scope

This report describes the quality of surface 

water and bottom material at selected sites within 

the Barataria Preserve of Jean Lafitte National 

Historical Park and Preserve in 1999 and 2000 

and discusses changes that occurred from an earlier survey done in 1981-82 (Garrison, 1982). 

Organochlorine, chlorophenoxy acid, and organophosphorus pesticides; PCB’s; and trace elements 

were analyzed in surface water and bottom material at three sites that were sampled in the earlier 

survey. These constituents were of concern 

because of human health issues. Selected nutrients and inorganic ions important to the ecological integrity of the peat marshes were sampled at 

six surface-water sites in the Barataria Preserve. 

The data are presented in graphs and tables with a 

discussion of their significance. The report will 

provide a baseline for evaluating changes to the 

quality of water and bottom material that may 

occur in the Barataria Preserve after the Davis 

Pond Diversion Structure becomes operational.

Description of Study Area

The Barataria Preserve is a healthy 

20,600-acre wetland complex comprised of 

swamp forests and large expanses of freshwater 

peat marshes, with interconnected canals and 

waterways. Peat marshes in a subtropical coastal 

setting are a unique natural resource. Coastal 

Louisiana is one of the few locations worldwide 

where this wetland type covers large areas 

(Swarzenski, 1992). Because its substrate is 

made of organic material produced by plant 

growth and roots rather than accreting clay and 

silt, peat marshes are vulnerable to changes in 

water quality which could affect the production 

and decomposition of organic matter. 

Approach and Methods

Organic compounds and trace metals were 

sampled three times in water and once in bottom 

material at three sites that were sampled during 

the 1981-82 survey. This sampling focused on 

constituents important to human health and 

aquatic life in waterways. Major nutrients and 

inorganic ions were sampled between 6 and 11 

times at 6 sites newly established for the current 

survey. This sampling was concerned more with 

constituents important to the integrity of the wetlands of the preserve. 

Organic Compounds and Trace Elements

Water and bottom material were collected 

at three sites, Bayou Segnette near Barataria, 

Bayou Segnette 4.6 miles south of Westwego, and 

Kenta Canal northwest of Crown Point, and analyzed for organic compounds and trace elements 

(fig. 2) to determine if quality had changed over 

time. These sites originally were sampled in the 

1981-82 survey (Garrison, 1982). The samples 

collected were analyzed for a diverse group of 

pesticides, including historically used organochlorine insecticides (such as DDT and its metabolites DDD and DDE, chlordane, and dieldrin), 

some currently used organophosphorus and chlorophenoxy acid pesticides (such as diazinon and 

2,4-D, respectively) and some industrial chemicals (PCB’s and polychlorinated naphthalenes or 

PCN’s). These man-made, persistent organic 

compounds were produced and used in great 

quantities over many years (Larsen and others, 

1997; U.S. Environmental Protection Agency, 

1994). They have been introduced into streams 

and rivers from direct discharges, atmospheric 

deposition, and runoff from the land surface. In 

general, these organic compounds tend to sorb 

readily to particles, which can settle out of the 

water column onto bed material and remain for 

long periods of time. Organochlorine pesticides 

and PCB’s also bioaccumulate within the tissues 

of aquatic biota. Their persistence in the environment, accumulation in living tissue, and toxicity 

make them a concern to aquatic organisms and 

human health.

Concentrations of iron, manganese, and 

eight of the nine trace elements of environmental 

concern--arsenic, cadmium, chromium, copper, 

lead, mercury, nickel, and zinc--that are on the 

U.S. Environmental Protection Agency (USEPA) 

list of 126 Priority Pollutants (U.S. Environmental Protection Agency, 1994) were determined for 

the bottom-material samples, and, with the exception of arsenic, for surface-water samples at the 

three sites. Arsenic, cadmium, copper, lead, mercury, and zinc can be toxic to aquatic life. Some 

of the more toxic trace elements, such as mercury, cadmium, and lead, tend to bioaccumulate 

6

in aquatic food chains, producing a health risk to 

aquatic biota and humans. Trace elements in the 

aquatic environment can occur naturally from 

weathering of mineral in rocks and soils and from 

the combustion of fossil fuels, industrial discharges, automobile emissions, and trace constituents in pesticides and fertilizers. 

Canadian sediment quality guidelines 

(Canadian Council of Ministers of the Environment, 1999) were used to interpret potential toxicity of measured sediment concentrations of 

selected trace metals and organic compounds to 

aquatic life at the preserve. State and Federal 

standards have not yet been established in the 

United States. Canadian Council of Ministers of 

the Environment (CCME) (1999) provides Interim 

Sediment Quality Guidelines (ISQG’s) and Probable Effects Levels (PEL’s) for constituents of 

interest. These provide a means of evaluating the 

potential toxicity of the concentrations of organic 

compounds and trace metals actually measured at 

the preserve. Adverse biological effects are 

expected to occur rarely at concentrations of 

chemicals lower than ISQG’s. Concentrations 

above PEL’s indicate that some adverse biological effects could be expected. 

In this report, ISQG’s and PEL’s determined for freshwater sediments were used. 

ISQG’s and PEL’s for marine sediments tend to 

be slightly higher for trace elements and slightly 

lower for organic compounds (Canadian Council 

of Ministers of the Environment, 1999). Longterm average salinity in waters surrounding the 

Barataria Preserve ranges from 0.5 to 4 ppt (Conner and others, 1986), well below the 15 to 25 ppt 

more typical of marine environments. The sediment guidelines are not intended to be used for 

regulatory purposes or as targets for cleaning up 

an environment, nor are they intended to be used 

to evaluate the suitability for dredging. 

Surface-water samples for organic compounds and trace elements were collected on 

August 25, 1999, February 4, 2000, and May 31, 

2000. Kenta Canal northwest of Crown Point was 

inaccessible due to floating aquatic plants during 

August 1999 and was not sampled at that time. 

Sample bottles were filled by submerging them 

6 inches below the water surface for whole water 

analyses, or by pulling water directly from the 

waterway through a 0.45-micrometer filter (certified for trace-metal analyses) and into bottles 

using teflon tubing and a peristaltic pump. 

Waterways of the preserve are shallow; flow is 

sluggish and bi-directional. For these reasons, 

and to maintain consistency with the sampling 

techniques used in the earlier survey, samples 

were collected using single-grab samples. A 

duplicate sample collected in February 2000 indicated cross sections were well mixed. 

Bottom-material samples were collected 

once from each of the three sites. Five bottommaterial samples of about 130 cubic inches each 

were collected from each site with a teflon-coated 

ponar, composited, and analyzed for organic compounds and trace elements. Bottom-material samples were not sieved prior to analysis. More 

detailed explanations of sampling procedures are 

discussed in the National Field Manual (U.S. 

Geological Survey, 1997) and, for trace elements, 

Horowitz and others (1994). One bottom-material sample was collected in duplicate for quality 

control.

 Nutrients and Major Inorganic Ions

Concentrations of nutrients and major inorganic ions such as chloride and sulfate may affect 

the marshes of the Barataria Preserve in several 

ways. Nutrients affect marsh productivity. Their 

abundance determines whether below-ground or 

above-ground production dominates. Peat-based 

wetlands are adapted to low-nutrient conditions 

by extensive root systems which can capture the 

scarce nutrients; they build their own (peat) substrate. If nutrient concentrations increase, aboveground production may increase and substrate 

growth may decrease. Moreover, elevated nutrients may accelerate decomposition of the peat 

substrate. 

Plants that dominate the Barataria Preserve 

segregate based on their tolerance to chlorides 

and sulfides, the reduced form of sulfate. Most of 

the plants growing in the Barataria Preserve are 

tolerant of only the low-salinity conditions that 

normally dominate surface water in this part of 

the Barataria Basin (Conner and others, 1986). If 

intrusions of marine water into the Barataria Preserve occur with sufficient duration and frequency, concentrations of chlorides and sulfates in 

the Barataria Preserve will increase, and plant 

communities likely will shift to species that are 
7

not able to build the peat substrate that is essential to the long-term stability of the Barataria Preserve marshes.

Surface-water sampling to determine calcium and magnesium concentrations will allow 

tracking of river water circulation through Barataria Preserve waterways after the Davis Pond 

Freshwater Diversion becomes operational. Calcium:magnesium ratios are typically about 1:1 or 

less in water not affected by Mississippi River 

water. Ratios of the same inorganic ions in Mississippi River water generally are closer to 3:1. 

In this report, brackish is used as a relative term 

to indicate water with some marine influence, but 

it does not refer to a particular salinity or specific 

conductance value.

Water samples were collected, filtered, and 

analyzed for ammonia, nitrite+nitrate, organic 

nitrogen, orthophosphate, and chloride, sulfate, 

calcium, magnesium, and potassium ions at six 

newly established sites in the preserve on 4-to-6 

week intervals from March 1999 to May 2000 

(fig. 2). Specific conductance was measured in 

the field. The six new sites bracket each of the 

three sites sampled in the earlier survey. Whereas 

the earlier sites were selected to sample the waterquality conditions at the confluence of different 

waterways, the new sites were selected to represent water quality of individual waterways. Segnette Waterway west of Crown Point (N-7) is 

located in Segnette Waterway below the intersection with Pipeline Canal. Pipeline Canal west of 

Crown Point (N-6) is located on Pipeline Canal 

several hundred yards northeast of this intersection. Pipeline Canal serves as an entry and exit 

point of water from the interior of the Barataria 

Preserve to Segnette Waterway. These two sites 

bracket the original 1981-82 survey site Bayou 

Segnette near Barataria. Segnette Waterway northwest of Crown Point (N-4) is located on Segnette 

Waterway, but several mi north of Segnette Waterway west of Crown Point (N-7). This site is 

located south of several non-sewered rural residences, and also south of the site Bayou Segnette 

4.6 miles south of Westwego. Tarpaper Canal 

south of Westwego (N-9) is located on Tarpaper 

Canal, just upstream from the intersection of Tarpaper Canal and Segnette Waterway. This site 

also is surrounded by non-sewered rural residences. Keyhole 6 south of Westwego (N-8) is 

near the original 1981-82 survey site Kenta Canal 

northwest of Crown Point and is located on an 

interior canal surrounded by marshes. Kenta 

Canal north of Barataria (N-10) is on Kenta Canal 

and was frequently inaccessible for sampling during 1999 and 2000 due to blockage by hyacinth 

rafts.

Segnette Waterway northwest of Crown 

Point (N-4) and Segnette Waterway west of 

Crown Point (N-7) are located on the north-south 

trending Segnette Waterway, through which water 

can quickly enter or leave the Barataria Preserve. Tarpaper Canal south of Westwego (N-9) 

and Pipeline Canal west of Crown Point (N-6), as 

well as Keyhole 6 south of Westwego (N-8), are 

collectively referred to as interior sites. Most of 

the water entering Pipeline Canal, Tarpaper 

Canal, and other interior waterways in the Barataria Preserve from an external source other than 

precipitation enters through Segnette Waterway. 

Acknowledgments

The author thanks Sandee Dingmann and 

David Muth of the National Park Service for their 

assistance with all aspects of the survey. Stanley 

C. Skrobialowski, Roland W. Tollett, and John K. 

Lovelace of the U.S. Geological Survey assisted 

with sample collection.

QUALITY OF SURFACE WATER AND 

BOTTOM MATERIAL, 1999-2000

Waterways in the Barataria Preserve contain a mixture of marine-influenced water that 

enters from the south, and freshwater that enters 

from the north and east. Water also enters the 

preserve from Lake Salvador through Bayou 

Bardeaux and varies in its characteristics from 

fresh to slightly brackish. Specific conductance 

values were less than 3,000 μS/cm (microsiemens per centimeter at 25 degrees Celsius) in surface water throughout the Barataria Preserve from 

March through September 1999 (fig. 3). Specific 

conductance values increased over the next 2 

months and generally remained between 5,000 

and 6,000 μS/cm through May 2000. The 

increase in specific conductance at Kenta Canal 

north of Barataria (N-10), in the interior of the 

preserve, occurred later than the increase at other 

sites. Specific conductance remained low during 

the fall and winter.

9

Salinity for this area of Barataria basin typically is at its annual high during the fall (Byrne 

and others, 1976; Swarzenski 1992, p. 39). Fall 

salinity peaks are usually followed by annual lows 

in late winter. However, southern Louisiana experienced a drought that started during the fall of 

1999 and became progressively more severe into 

the summer of 2000 (E.M. Swenson, Louisiana 

State University Coastal Ecology Institute, written commun., 2001). Salinity in the Barataria 

Preserve was elevated for at least 8 months. 

Surface Water

Of the 32 different organic compounds analyzed in the whole-water samples, the only 

organic compound detected in surface water was 

2,4-D (2,4-dichlorophenoxy acetic acid) (table 1), 

which is an aquatic herbicide commonly sprayed 

on floating aquatic plants that clog many waterways in south Louisiana, including those in the 

Barataria Preserve. It was detected at the two 

sites sampled in August 1999 but was not 

detected at any sites during subsequent sampling 

trips. The hydrophobic organochlorine pesticides 

and PCB’s were not detected in surface water 

during the period of sampling (table 1). This is 

expected because these pesticides tend to bind to 

sediments and are more likely to be detected in 

bottom material.

Iron, manganese, and three of the nine 

trace elements of environmental concern--copper, 

nickel, and zinc--were detected in dissolved and 

whole-water samples at the three sites (table 2). 

Concentrations were substantially less than values at which aquatic life would be impaired 

(Canadian Council of Ministers of the Environment, 1999; U.S. Environmental Protection 

Agency, 2002). Beryllium, cadmium, chromium, 

lead, and mercury were not detected in any samples at the three sites.

Results of the sampling for nutrients are 

listed in table 3 and shown in figure 4. Laboratory reporting levels (LRL’s) for nitrite+nitrate 

and orthophosphate were 0.002 mg/L (milligrams 

per liter) with the exception of samples collected 

at Keyhole 6 south of Westwego (N-8) from 

March through September 1999. The LRL’s were 

0.05 mg/L for these samples due to differences in 

analytical techniques. Means for constituents 

which had concentrations below the LRL were 

calculated by substituting the LRL as the value. 

This approach resulted in somewhat higher means 

than would have occurred if other methods had 

been used. A mean for nitrite+nitrate at site Keyhole 6 south of Westwego (N-8) was not calculated because of the different LRL’s.

Nitrite+nitrate, as nitrogen, concentrations 

ranged from less than 0.002 to 0.19 mg/L 

(table 3). Highest concentrations were at the two 

southernmost sites in the Barataria Preserve, Pipeline Canal west of Crown Point (N-6) and Segnette Waterway west of Crown Point (N-7). 

Ammonia, as nitrogen, values ranged from less 

than 0.01 to 0.16 mg/L. Organic nitrogen concentrations ranged from 0.49 to 1.3 mg/L; the 

highest concentration was detected at Keyhole 6 

south of Westwego (N-8). Segnette Waterway 

northwest of Crown Point (N-4) and Tarpaper 

Canal south of Westwego (N-9), closest to the 

non-sewered rural residences, and Keyhole 6 

south of Westwego (N-8), had slightly lower 

mean organic nitrogen concentrations than Pipeline Canal west of Crown Point (N-6) and Segnette Waterway West of Crown Point (N-7). 

Orthophosphate, as phosphorus, concentrations 

ranged from less than 0.002 to 0.14 mg/L. Orthophosphate concentrations were highest in late 

summer to fall at all sites (fig. 4), and they were 

generally low from November to March. Ammonia concentrations were low in samples collected 

earlier in the survey but tended to increase with 

time. Organic nitrogen concentrations were 

slightly higher at Pipeline Canal west of Crown 

Point (N-6) and Kenta Canal north of Barataria 

(N-10).

Minimum concentrations of inorganic ions 

at the two sites on Segnette Waterway, Segnette 

Waterway northwest of Crown Point (N-4) and 

Segnette Waterway west of Crown Point (N-7), 

tended to be similar and somewhat higher than 

those for Tarpaper Canal south of Westwego 

(N-9), Pipeline Canal west of Crown Point (N-6), 

and Keyhole 6 south of Westwego (N-8) (table 4). 

The marine influence on water quality became 

more dominant after September 1999 (figs. 5, 6). 

Concentrations of inorganic ions increased at all 

sampling sites in the preserve at this time. Calcium, magnesium, and potassium concentrations 

would be expected to be somewhat lower when 

conditions are dominated more by freshwater 

inflow. 
10

Table 1. Whole-water (total recoverable) pesticide and polychlorinated biphenyl concentrations in 

surface water of the Barataria Preserve, Jean Lafitte National Historical Park and Preserve, Louisiana, 

August 1999 to May 2000

[Concentrations are in micrograms per liter. <, less than; --, not determined]

1

Site was inaccessible on August 25, 1999.

Constituent

Bayou Segnette near 

Barataria

Kenta Canal northwest 

of Crown Point1

Bayou Segnette 4.6 miles 

south of Westwego

08-25-99 02-04-00 05-31-00 02-04-00 05-31-00 08-25-99 02-04-00 05-31-00

2,4-DP (2,4-dichlorophenoxy butanioc acid) <0.01 <0.04 <0.04 <0.04 <0.04 <0.01 <0.04 <0.04

2,4,5-T (2,4,5-trichlorophenoxy acetic acid) <.01 <.03 <.03 <.03 <.03 <.01 <.03 <.03

2,4-D (2,4-dichlorophenoxy acetic acid) .12 <.05 <.05 <.05 <.05 0.13 <.05 <.05

Aldrin <.013 <.013 <.013 <.013 <.013 <.013 <.013 <.013

Carbophenothion <.01 <.01 <.01 <.01 <.01 <.01 <.01 <.01

Chlordane <.1 <.1 <.1 <.1 <.1 <.1 <.1 <.1

Chlorpyrifos <.01 <.01 <.01 <.01 <.01 <.01 <.01 <.01

DEF (5,5,5-tributylphosphorotrithioate) <.01 <.02 <.02 <.02 <.02 <.01 <.02 <.02

Diazinon <.01 <.02 <.02 <.02 <.02 <.01 <.02 <.02

Dieldrin <.009 <.009 <.009 <.009 <.009 <.009 <.009 <.009

Disulfoton <.01 <.03 <.03 <.03 <.03 <.01 <.03 <.03

Endosulfan I <.015 <.015 <.015 <.015 <.015 <.015 <.015 <.015

Endrin <.014 <.014 <.014 <.014 <.014 <.014 <.014 <.014

Ethion <.01 <.01 <.01 <.01 <.01 <.01 <.01 <.01

Fonofos (dyfonate) <.01 <.01 <.01 <.01 <.01 <.01 <.01 <.01

Heptachlor epoxide <.009 <.009 <.009 <.009 <.009 <.009 <.009 <.009

Heptachlor <.011 <.011 <.011 <.011 <.011 <.110 <.011 <.011

Lindane <.012 <.012 <.012 <.012 <.012 <.012 <.012 <.012

Malathion <.01 <.03 <.03 <.03 <.03 <.01 <.03 <.03

Methoxychlor <.01 <.01 <.01 <.01 <.01 <.01 <.01 <.01

Methyl parathion <.01 <.01 <.01 <.01 <.01 <.01 <.01 <.01

Mirex <.01 <.01 <.01 <.01 <.01 <.01 <.01 <.01

P,P′-DDD

(para, para-DDD) 

<.014 <.014 <.014 <.014 <.014 <.014 <.014 <.014

P, P′-DDE <.016 <.016 <.016 <.016 <.016 <.016 <.016 <.016

P, P′-DDT <.017 <.017 <.017 <.017 <.017 <.017 <.017 <.017

Parathion <.01 <.01 <.01 <.01 <.01 <.01 <.01 <.01

PCB’s <.1 <.1 <.1 <.1 <.1 <.1 <.1 <.1

PCN’s <.1 <.1 -- <.1 -- <.1 <.1 --

Perthane <.1 <.1 -- <.1 -- <.1 <.1 --

Phorate <.01 <.02 <.02 <.02 <.02 <.01 <.02 <.02

2,4,5-TP (2,4,5-Trichlorophenoxyproprionic acid)<.01 <.03 <.03 <.03 <.03 <.01 <.03 <.03

Toxaphene <1 <1 <1 <1 <1 <1 <1 <1
11

Table 2. Whole-water (total recoverable) and dissolved trace-element, iron, and manganese concentrations in surface water of the Barataria Preserve, Jean Lafitte National Historical Park and Preserve, 

Louisiana, August 1999 to May 2000

[Concentrations are in micrograms per liter. <, less than; --, not determined; E, estimated; M, presence verified, 

not quantified]

1

Site was inaccessible on August 25, 1999.

Constituent

Bayou Segnette near 

Barataria

Kenta Canal northwest 

of Crown Point1

Bayou Segnette 4.6 miles 

south of Westwego

08-25-99 02-04-00 05-31-00 02-04-00 05-31-00 08-25-99 02-04-00 05-31-00

Beryllium, total 

recoverable 

<4.00 <5.00 <4.00 <5.00 <3.00 <4.00 <5.00 <4.00

Beryllium, dissolved <1.60 <6.40 <1.60 <4.80 <1.60 <1.60 <4.80 <1.60

Cadmium, total 

recoverable 

 <10.0 <.11 <4.00 <.11 <3.00 <10.0 <.11 <4.00

Cadmium, dissolved <1.00 <2.00 <.28 <.14 <.14 <1.00 <2.00 <.28

Chromium, total 

recoverable 

<1 <5 <1 <2 <1 <1 <5 <1

Chromium, dissolved <1.0 <5.0 <.8 <2.0 <.8 <1.0 <5.0 <.8

Copper, total

recoverable 

 <12.0 E.9 <4.0 E.9 <3.0 <12.0 E.8 <4.0

Copper, dissolved <1.0 <2.0 <2.6 <1.3 <1.3 1.3 <2.0 <2.6

Iron, total

recoverable 

180 200 <20 310 140 190 170 110

Iron, dissolved M <40 <100 60 140 M <30 <50

Lead, total

recoverable 

<1 M <4 <1 <3 <1 M <4

Manganese, total

recoverable 

96 35 274 207 586 102 27 409

Manganese, 

dissolved 

57.7 14.2 281 171 571 15.6 11.8 288

Mercury, total

recoverable 

-- <.30 <.30 <.30 <.30 -- <.30 <.30

Mercury, dissolved <.10 <.23 <.23 <.23 <.23 <.10 <.23 <.23

Nickel, total

recoverable 

<50 <2 8 <2 5 <50 E1 7

Selenium, total <1.0 <2.6 <4.0 <2.6 <3.0 <1.0 <2.6 <4.0

Zinc, total 

recoverable 

<40 E19 <17 E21 10 <40 <31 <17

Zinc, dissolved <20 E12 <200 20 <100 <20 E15 <100
12

Table 3. Concentrations of dissolved nutrients in surface water of the Barataria Preserve, Jean Lafitte 

National Historical Park and Preserve, Louisiana, March 1999 to May 2000

[Data for Kenta Canal north of Barataria (N-10) are not summarized. mg/L, milligrams per liter; <, less than; --, not 

determined]

Site name

(number in fig. 2)

Nitrogen, nitrite+nitrate

(mg/L as N)

Nitrogen, ammonia

(mg/L as N)

Mean± standard 

deviation Minimum Maximum Mean±standard deviation Minimum Maximum

Pipeline Canal west of Crown 

Point (N-6)

0.01±0.03 <0.002 0.10 0.04±0.06 <0.01 0.16

Segnette Waterway west of 

Crown Point (N-7)

.04±07 <.002 .19 .06±.06 <.01 .14

Segnette Waterway northwest 

of Crown Point (N-4)

.01±.02 <.002 .05 .03±.01 <.01 .09

Tarpaper Canal south of 

Westwego (N-9)

.01±.01 <.002 .03 .03±.01 <.01 .09

Keyhole 6 south of Westwego 

(N-8)

 -- <.002 .10 .04±.01 <.01 .12

Nitrogen, organic

(mg/L as N)

Orthophosphate

(mg/L as P)

Mean±standard 

deviation Minimum Maximum Mean± standard 

deviation Minimum Maximum

Pipeline Canal west of Crown 

Point (N-6)

0.84±0.24 0.56 1.2 0.04±0.03 <0.002 0.10

Segnette Waterway west of 

Crown Point (N-7)

.89±.16 .49 1.10 .04±.05 <.002 .14

Segnette Waterway northwest 

of Crown Point (N-4)

.72±.15 .49 1.00 .05±.06 <.002 .14

Tarpaper Canal south of 

Westwego (N-9)

.73±.13 .60 .95 .06±.05 <.002 .13

Keyhole 6 south of Westwego 

(N-8)

.73±.24 .54 1.3 .05±.03 <.02 .11
Figure 4. Dissolved orthophosphate, ammonia, and organic nitrogen concentrations in surface water of the Barataria Preserve, Jean Lafitte National Historical Park and Preserve, Louisiana, March 1999 to May 2000.

Mar. 1 June 1 Sept. 1 Dec. 1 Mar. 1 June 1

0.20

0.15

0.10

0.05

0.00

0.3

0.2

0.1

0.0

1.5

1.0

0.5

0.0

1.5

1.0

0.5

0.0

2.0

1.5

1.0

0.5

0.0

2.0

0.3

0.2

0.1

0.0

0.3

0.2

0.1

0.0

0.20

0.15

0.10

0.05

0.00

0.20

0.15

0.10

0.05

0.00

DIS

S

OLV

E

D

O

R

G

A

NIC

NIT

R

O

G

E

N,

IN

MILLIG

R

A

M

S

P

E

R LIT

E

R

A

S

N

DIS

S

OLV

E

D

A

M

M

O

NIA, IN

MILLIG

R

A

M

S

P

E

R LIT

E

R

A

S

N

DIS

S

OLV

E

D

O

R

T

H

O

P

H

O

S

P

H

AT

E,

IN

MILLIG

R

A

M

S

P

E

R LIT

E

R

A

S

P

Near intersection of Segnette 

Waterway and Pipeline Canal Near Kenta Canal and Twin Canals Near Segnette Waterway and Tarpaper Canal

N-6 Pipeline Canal west of Crown Point

N-7 Segnette Waterway west of Crown Point

N-8 Keyhole 6 south of Westwego

N-10 Kenta Canal north of Barataria

N-4 Segnette Waterway northwest of Crown Point

N-9 Tarpaper Canal south of Westwego

1999 2000 1999 2000 1999 2000

Nitrite+nitrate is not shown because of the frequent non-detections during the analyses.

B.D., Below detection.

B.D.

B.D.

B.D.

B.D.

B.D.

B.D.

B.D.

Mar. 1 June 1 Sept. 1 Dec. 1 Mar. 1 June 1 Mar. 1 June 1 Sept. 1 Dec. 1 Mar. 1 June 1

13
14

 Table 4. Concentrations of dissolved inorganic ions in surface water of the Barataria Preserve, Jean 

Lafitte National Historical Park and Preserve, Louisiana, March 1999 to May 2000

 [Data for Kenta Canal north of Barataria (N-10) are not summarized. mg/L, milligrams per liter]

Site name

(number in fig. 2)

Calcium

(mg/L as Ca)

Magnesium

(mg/L as Mg)

Mean± standard 

deviation Minimum Maximum Mean± standard deviation Minimum Maximum

Pipeline Canal west 

of Crown Point (N-6)

50±19 20 78 82±45 22 140

Segnette Waterway 

west of Crown Point 

(N-7)

50±17 28 78 84±48 26 166

Segnette Waterway 

northwest of Crown 

Point (N-4)

46±17 29 83 74±49 24 169

Tarpaper Canal south 

of Westwego (N-9)

48±18 24 79 66±42 20 150

Keyhole 6 south of 

Westwego (N-8)

43±19 19 76 62±44 17 137

Potassium

(mg/L as K)

Sulfate

(mg/L as SO4)

Chloride

(mg/L as Cl)

Mean± 

standard 

deviation

Minimum Maximum

Mean±

standard 

deviation

Minimum Maximum

Mean±

standard 

deviation

Minimum Maximum

Pipeline Canal west 

of Crown Point (N-6)

24±14 4 42 173±116 23 236 1,690±544 695 2,290

Segnette Waterway 

west of Crown Point 

(N-7)

26±14 8 50 177±99 52 349 1,850±512 1,450 2,740

Segnette Waterway 

northwest of Crown 

Point (N-4)

23±15 8 51 161±106 45 379 1,700±628 904 2,830

Tarpaper Canal south 

of Westwego (N-9)

21±13 4 44 123±82 22 283 1,440±676 679 2,420

Keyhole 6 south of 

Westwego (N-8)

19±14 3 40 118±89 11 249 846±709 252 2,210


17

Calcium, magnesium, and potassium concentrations were lower at the interior sites than 

the two sites on Segnette Waterway. Calcium 

concentrations ranged from 19 to 83 mg/L, magnesium from 17 to 169 mg/L, and potassium from 

3 to 51 mg/L (table 4). Sulfate and chloride concentrations also were generally lower in interior 

sites than sites along Segnette Waterway. Maximum sulfate concentrations were 379 and 

349 mg/L and maximum chloride concentrations 

were 2,830 and 2,740 mg/L at Segnette Waterway northwest of Crown Point (N-4) and Segnette Waterway west of Crown Point (N-7), 

respectively (table 2). At two interior sites Keyhole 6 south of Westwego (N-8) and Tarpaper 

Canal south of Westwego (N-9), maximum sulfate concentrations were 249 and 283 mg/L, 

respectively – over 60 mg/L less than Segnette 

Waterway sites and maximum chloride concentrations were 2,210 and 2,420 mg/L, respectively – 

over 300 mg/L less than Segnette Waterway sites. 

Interior site Pipeline Canal west of Crown Point 

(N-6) was an exception with the highest maximum sulfate concentration of all sites (398 mg/L) 

and a mean chloride concentration (1,690 mg/L) 

similar to site Segnette Waterway northwest of 

Crown Point (N-4) (1,700 mg/L). Pipeline Canal 

west of Crown Point (N-6) is in the southernmost 

portion of the Barataria Preserve and is located 

fairly close to Segnette Waterway west of Crown 

Point (N-7). Marine water typically enters the 

preserve from the south through Segnette Waterway and can flow into Pipeline Canal.

Ratios of calcium to magnesium concentrations were about 1:1 or less (fig. 7). The ratio of 

the same ion concentrations in water from the 

Mississippi River was closer to 3:1, and concentrations in the river ranged over a much smaller 

range compared to those in surface water of the 

Barataria Preserve.

Bottom Material

Few organic compounds were detected in 

bottom material. LRL’s varied spatially, somewhat confounding interpretations. PCB’s and 

chlordane were detected in bottom material 

(table 5). Concentrations of DDD were below 

LRL’s. DDT and DDE were detected at Bayou 

Segnette 4.6 miles south of Westwego. The relative proportions of organic and mineral sediment 

making up the sample affect the LRL’s (Horowitz, 1991). Samples with higher organic matter 

content typically have higher LRL’s. The LRL’s 

were uniformly higher for samples from Kenta 

Canal northwest of Crown Point, as was percent 

moisture. Although organic matter content was 

not determined, it is likely that levels are higher 

at the Kenta Canal site.

Many trace elements, among them metals 

of environmental concern, were detected in bottom material at all three of the sampled sites 

(table 6). For example, arsenic concentrations 

ranged from 4 to 9 μg/g (micrograms per gram) 

and lead concentrations from 20 to 31 μg/g. Mercury concentrations in bottom material ranged 

from 0.01 to 0.03 μg/g. 

COMPARISON BETWEEN 1981-82 AND 

1999-2000 SURVEYS

Salinity, as indicated by specific conductance, was elevated in surface water in the Barataria Preserve during much of the 1981-82 and 

the 1999-2000 surveys (fig. 8). During the earlier survey, water was initially more brackish, but 

became fresher late in the survey. During the 

present survey, the water became more brackish 

over the course of sampling and remained this 

way at least through the end of sampling.

Analysis of the long-term salinity record at 

Bayou Barataria at Lafitte from 1955 to 1987 

indicates that periods when more saline conditions dominate this part of Barataria basin for 100 

or more days per year occur less than one-third of 

the time (Swarzenski, 1992, p. 39). However, 

because both surveys at the Barataria Preserve 

were done during periods when such conditions 

prevailed, the water type sampled and analyzed 

was atypical and water quality possibly less representative of normal conditions. For example, 

organic constituents and trace metals that may 

come from anthropogenic sources and enter the 

preserve may have been missed. Freshwater 

inflow may have been under-represented in surface-water samples collected during both surveys. However, bottom material integrates 

conditions of surface water over long time periods and is more representative of exposure of 

park waterways to hydrophobic compounds 

(Horowitz, 1991). 
18

Surface Water

The herbicide 2,4-D was detected in surface water during the 1981-82 survey (Garrison, 

1982) and during the 1999-2000 survey. Diazinon also was detected in surface-water samples 

during the 1981-82 survey (Garrison, 1982) but 

not in the 1999-2000 survey. Total recoverable 

and dissolved mercury concentrations at all three 

sites were below LRL’s of 0.3 μg/L in the 1999-

2000 survey. Dissolved mercury concentrations 

as high as 1.1 and 1.7 μg/L had been reported 

from Bayou Segnette near Barataria and Bayou 

Segnette 4.6 miles south of Westwego for the 

1981-82 survey (Garrison, 1982). Similarly, dissolved chromium concentrations at all three sites 

were below LRL’s of 5 μg/L during the 1999-

2000 survey, but were between 10 and 20 μg/L at 

the same sites during the 1981-82 survey. 

Nitrite+nitrate and organic nitrogen concentrations apparently were higher in the 1981-82 

survey than in the 1999-2000 survey (fig. 9). It is 

difficult to interpret the differences in nitrogen 

between the two surveys. Reasons for the large 

differences are not clear, and could be due to an 

artifact of sampling or analytical methods. Calcium, magnesium, and potassium concentrations 

were similar between the two surveys (fig. 10). 

Mean and median concentrations generally were 

slightly lower at Keyhole 6 south of Westwego 

(N-8), Kenta Canal north of Barataria (N-10), and 

Kenta Canal northwest of Crown Point than at the 

other four sites sampled.

Sulfate and chloride concentrations were 

similar during the two surveys among bracketed 

locations in the preserve (fig. 11), but concentrations at the interior sites Keyhole 6 south of 

Westwego (N-8), Kenta Canal north of Barataria 

Figure 7. Ratio of dissolved calcium to magnesium in the Mississippi River and surface water 

of the Barataria Preserve, Jean Lafitte National Historical Park and Preserve, Louisiana, 1999-

2000.

0

0 20 40 60 80 100

20

40

60

80

100

120

140

160

180

Surface-water sampling sites in Barataria Preserve (1999-2000)

Mississippi River(1999-2000)

EXPLANATION

M

A

G

N

E

SIU

M, NI MILLIG

R

A

M

S

P

E

R LIT

E

R

A

S

Mg

CALCIUM, IN MILLIGRAMS 

PER LITER AS Ca

3:1

1:1
19

Table 5. Pesticide and polychlorinated biphenyl concentrations in bottom material of the Barataria Preserve, Jean Lafitte National Historical Park and Preserve, Louisiana

[Concentrations are in micrograms per kilogram. <, less than; E, estimated; --, not determined]

Constituent

Bayou Segnette 

near Barataria

Kenta Canal northwest of Crown 

Point

Bayou Segnette 4.6 miles 

south of Westwego

08-25-99 02-04-00 08-25-99

2, 4-DP, total <0.1 <0.1 <0.1

2, 4, 5-T, total <.1 <.1 <.1

2, 4-D, total <.1 <.1 <.1

Aldrin, total <.4 <1.0 <.2

Chlordane, total <6 <15 E2

Diazinon, total <.4 <1.0 <.4

Dieldrin, total <.4 <1.0 <.2

Endosulfan, total <.4 <1.0 <.2

Endrin, total <.4 <1.0 <.2

Ethion, total <.4 <1.0 <.4

Heptachlor epoxide, total <.4 <1.0 <.2

Heptachlor, total <.4 <1.0 <.2

Lindane, total <.4 <1.0 <.2

Malathion, total <.4 <1.0 <.4

Methoxychlor, total <5 <12 <2

Methyl parathion, total <.4 <1.0 <.4

Mirex, total <.4 <1.0 <.2

P,P′-DDD, recoverable 

(para, para-DDD)

<1.0 <2.5 <.5

P,P′-DDE, recoverable <.4 <1.0 .9

P,P′-DDT, recoverable <1.0 <2.5 E.2

Parathion, total <.4 <1.0 <.4

PCB’s, total 15 <25 9

Silvex, total <.1 <.1 <.1

Toxaphene, total <100 <250 <50

Trithion, total <.4 -- <.4
20

Table 6. Trace-element, iron, and manganese concentrations in bottom material of the Barataria 

Preserve, Jean Lafitte National Historical Park and Preserve, Louisiana

[Concentrations are in micrograms per gram.]

 Constituent

Bayou Segnette 

near Barataria

Kenta Canal northwest of Crown PointBayou Segnette 4.6 miles 

south of Westwego

08-25-99 02-04-00 08-25-99

Arsenic, total 74 9

Cadmium, recoverable 0.5 0.4 0.5

Chromium, recoverable 21 12 16

Copper, recoverable 26 21 24

Iron 20,000 18,000 20,000

Lead, recoverable 26 20 31

Manganese, recoverable 510 380 510

Mercury, recoverable .03 .01 .03

Nickel, recoverable 28 17 27

Zinc, recoverable 100 80 10

Figure 8. Specific conductance at Bayou Segnette near Barataria, April 1981 to March 1982, 

and Segnette Waterway west of Crown Point, March 1999 to April 2000.

Bayou Segnette near Barataria (1981-82)

Segnette Waterway west of Crown Point (N-7) (1999-2000)

10,000

8,000

6,000

4,000

2,000

0

S

P

ECIFIC COND

UCTANC

E, IN MIC

ROSIEMENS PER CENTIMETER AT 

25 DEGREES CELSIUS

Mar. 1 June 1 Sept. 1 Dec. 1 Mar. 1 June 1

EXPLANATION



24

(N-10), and Kenta Canal northwest of Crown 

Point were slightly lower than at the other sites. 

Elevated concentrations of sulfate and chloride 

are related to the seawater influence of the Gulf 

of Mexico and are elevated in preserve water during the atypical conditions prevailing at the time 

of sampling. If higher chloride and sulfate concentrations become more frequent, shifts in marsh 

plant communities could be expected as chloride 

and sulfate concentrations in porewater of the 

marsh substrate increase. This increase would 

have adverse effects on the ability of the organic 

marsh substrate to accrete.

Bottom Material

The types of organic compounds and trace 

elements detected in bottom material during the 

1981-82 and the 1999-2000 surveys were similar. The interpretation of changes is complicated 

by the varying LRL’s between sites and studies. 

During 1999-2000, LRL’s often were higher than 

concentrations of constituents detected in the 

1981-82 survey (table 5). Higher method detection limits may reflect changes in LRL’s rather 

than a change in analytical technique.

Changes in chemical quality of bottom 

material occurred between the 1981-82 and the 

1999-2000 surveys. Organic compound and 

trace-element concentrations are listed in table 7 

with ISQG and PEL concentrations. Concentrations of organic compounds and trace elements 

detected in bottom material were generally well 

below PEL’s with the exception of chlordane and 

cadmium in the 1981-82 survey and arsenic in 

both surveys. Some chemicals persist in the environment, even though they have not been used for 

the past 25 or more years. DDT and its degradates DDD and DDE are examples. 

At Bayou Segnette 4.6 mi south of 

Westwego, concentrations of DDT in bottom 

material decreased from 1.2 μg/kg (micrograms 

per kilogram) during 1981-82 to 0.2 μg/kg in 

1999-2000 (table 7). At the other two sites, DDT 

was not detected; however, the LRL’s in the 

present survey were higher than the concentrations of the compound detected in the survey by 

Garrison (1982). At the site where DDT concentrations decreased, DDE concentrations increased 

from below the LRL during 1981-82 to 0.9 μg/kg 

in 2000, indicating that DDT has degraded over 

time at this site. Chlordane concentrations 

decreased in bottom material from the two sites 

on Bayou Segnette in the present survey compared to the earlier survey (Garrison, 1982). 

Chlordane concentrations possibly decreased at 

Kenta Canal northwest of Crown Point, but a 

direct comparison of data from the two surveys 

could not be made because of higher LRL’s during the 1999-2000 survey at this site.

PCB concentrations during the two surveys were similar at Bayou Segnette near Barataria, at about 14 to 15 μg/kg. At Bayou Segnette 

4.6 miles south of Westwego, PCB concentrations increased from less than 1.0 to 9 μg/kg from 

1981-82 to 1999-2000. At Kenta Canal northwest of Crown Point, PCB’s were not detected 

during either survey, but LRL’s were 25 μg/kg for 

the 1999-2000 survey, much higher than the 

0.1 μg/kg in the 1981-82 survey. PCB’s persisted in the Barataria Preserve, and appear to 

have increased in at least one site based on this 

sampling. Toxaphene concentrations were below 

LRL’s for both surveys, but LRL’s in the more 

recent survey were at least an order of magnitude 

higher.

Chlordane concentrations were above or 

close to the PEL at all three sites in the 1981-82 

survey (table 7). In the 1999-2000 survey, in contrast, chlordane was less than 25 percent of the 

PEL at Bayou Segnette 4.6 miles south of 

Westwego, and below LRL’s at the two other 

sites. P,P′-DDE concentrations in 1999-2000 

were about 63 percent of ISQG concentrations at 

Bayou Segnette 4.6 mi south of Westwego. All 

organic compounds were at most less than 25 percent of corresponding PEL’s in samples collected 

at the three sites in both surveys. 

Trace elements in bottom material showed 

differing trends (table 7). Cadmium concentrations consistently decreased by half or more from 

1981-82 to 1999-2000 at all three sites. Mercury 

concentrations were consistently lower at all three 

sites in the present survey, but the differences to 

the 1981-82 survey were quite small and could be 

within analytical error. Arsenic concentrations 

were comparable for both surveys and changed 

only slightly with time at each site. Chromium 

concentrations increased at all three sites from 

1981-82 to 1999-2000. Concentrations of copper 

and nickel increased in bottom material at the two 

sites on Bayou Segnette, but decreased at Kenta 

Canal northwest of Westwego. 
25

Table 7. Comparison of organic compound and trace-element concentrations in bottom material 

between the 1981-82 and 1999-2000 water-quality surveys at sites of the Barataria Preserve, Jean 

Lafitte National Historical Park and Preserve, Louisiana

[ISQG, Interim Sediment Quality Guideline; PEL, Probable Effects Level; μg/kg, micrograms per kilogram; <, less than; E, estimated; na, not 

available; μg/g, micrograms per gram; ns, not sampled] 

1

Source: Canadian Council of Ministers of the Environment, 1999.

2Source: Garrison, 1982.

Constituent ISQG1 PEL1 Bayou Segnette near 

Barataria

Kenta Canal northwest of Crown Point

Bayou Segnette 

4.6 miles south 

of Westwego

1981-822 1999-2000 1981-822 1999-2000 1981-822 1999-2000

Organic compounds (μg/kg)

PCB’s 34.1 277 14 15 <1.0 <25 <1.0 9

Chlordane 4.5 8.87 8 <6 8 <15 13 E2

P,P′-DDD

(para, para-DDD)

3.54 8.51 2.7 <1.0 <.1 <2.5 1.5 <.5

P,P′-DDE 1.42 6.75 <.1 <.4 .2 <1.0 <.1 .9

P,P′-DDT 1.19 4.77 <.1 <1.0 <.1 <2.5 1.2 E.2

Toxaphene na na <1.0 <100 <1.0 <250 <1.0 <50

Trace elements (μg/g)

Arsenic (As) 5.9 17.0 9 7 54 9 9

Cadmium (Cd) .6 3.5 1 .5 2 .4 2 .5

Chromium (Cr) 37.3 90 7 21 10 12 ns 16

Copper (Cu) 35.7 197 21 26 29 21 21 24

Lead (Pb) 35 91.3 20 26 20 20 30 31

Mercury (Hg) .17 .486 .04 .03 .05 .01 .04 .03

Nickel (Ni) na na 20 28 30 17 20 27

Zinc (Zn) 123 315 96 100 85 80 100 10

Arsenic in bottom material was above or 

similar to ISQG concentrations at all sites during 

both surveys (table 7). The arsenic concentration 

was 53 percent of the PEL (9 μg/g) at Bayou Segnette 4.6 mi south of Westwego in the 1999-2000 

survey. Cadmium, copper, and lead concentrations in bottom material also ranged around ISQG 

concentrations. Cadmium concentrations were 

50 percent or more above ISQG concentrations 

during the 1981-82 survey, but decreased to 

below ISQG concentrations in the 1999-2000 survey. Although chromium in bottom material 

increased at both sites for which comparative data 

were available, the concentrations at all three sites 

in this survey are about 20 percent or less of 

ISQG concentrations. No biological impairment 

to aquatic resources is expected below ISQG concentrations. Mercury in bottom material was less 

than 25 percent of ISQG concentrations for both 

surveys, as were the remaining trace elements.
26

SUMMARY AND CONCLUSIONS

The quality of water and bottom material in 

the Barataria Preserve of Jean Lafitte National 

Historical Park and Preserve, near New Orleans, 

was surveyed from March 1999 to May 2000. 

Organochlorine, chlorophenoxy acid, and organophosphate pesticides; polychlorinated biphenyls 

(PCB’s); and trace elements were analyzed in surface water and bottom materials at three sites previously sampled in 1981-82, and changes over 

time were evaluated. Surface water at six additional sites was sampled and analyzed for selected 

nutrients and major inorganic ions based on their 

importance to human health, the health of the 

marshes of the Barataria Preserve, or their usefulness in tracking the circulation of Mississippi 

River water in the Barataria Preserve. 

 Southern Louisiana was in a moderate to 

severe drought during most of the sampling 

period, which elevated salinity in the Barataria 

Preserve for at least 8 months. Specific conductance values were less than 3,000 μS/cm (microsiemens per centimeter at 25 degrees Celsius) in 

surface water throughout the Barataria Preserve 

from March through September of 1999. Specific conductance values increased over the next 

2 months and then generally remained between 

5,000 and 7,000 μS/cm. 

The herbicide 2,4-D was detected in water 

at both sites sampled in August 1999, but not at 

any site during the two later sampling periods. 

Iron, manganese, and the trace elements copper, 

nickel, and zinc were detected in dissolved and 

whole-water samples at all three sites. Concentrations of 2,4-D and the trace elements were substantially lower than values at which biological 

impairment would be likely.

Nitrite+nitrate, as nitrogen, concentrations 

ranged from less than 0.002 to 0.19 mg/L (milligrams per liter). Highest concentrations were 

found at the two southernmost sites in the Barataria Preserve, Segnette Waterway west of Crown 

Point (N-7) and Pipeline Canal west of Crown 

Point (N-6). Ammonia, as nitrogen, concentrations ranged from less than 0.01 to 0.16 mg/L. 

Organic nitrogen concentrations ranged from 0.49 

to 1.3 mg/L. Orthophosphate, as phosphorus, 

concentrations ranged from less than 0.002 to 

0.14 mg/L. Minimum concentrations of inorganic ions at the two sites on Segnette Waterway, 

Segnette Waterway northwest of Crown Point 

(N-4) and Segnette Waterway west of Crown 

Point (N-7), tended to be similar and somewhat 

higher than those for Tarpaper Canal south of 

Westwego (N-9), Pipeline Canal west of Crown 

Point (N-6), and Keyhole 6 south of Westwego 

(N-8). Calcium, magnesium, and potassium concentrations usually were lower at the interior sites 

than the two sites along the Segnette Waterway. 

Calcium concentrations ranged from 19 to 

83 mg/L, magnesium from 17 to 169 mg/L, and 

potassium from 3 to 51 mg/L. Ratios of calcium 

to magnesium were about 1:1 or less. Sulfate and 

chloride concentrations reached 379 and 

2,830 mg/L, respectively, at Segnette Waterway 

northwest of Crown Point (N-4). They were generally lower at interior sites than sites along Segnette Waterway.

PCB’s and chlordane, as well as DDT, were 

detected in bottom material. Trace elements, 

among them metals of environmental concern, 

were detected in bottom material at all three of 

the sampled sites. Arsenic concentrations ranged 

from 4 to 9 μg/g (micrograms per gram), and lead 

concentrations ranged from 20 to 31 μg/g. Mercury concentrations in bottom material ranged 

from 0.01 to 0.03 μg/g. 

 There were some similarities and some 

differences in water quality between the 1981-82 

and 1999-2000 surveys. Water was atypically 

more brackish in the Barataria Preserve for several continuous months both during the 1981-82 

and the 1999-2000 surveys. Periods when specific conductance remains high for 100 or more 

days per year occur less than one-third of the time 

in this part of the Louisiana coast. The water 

sampled during both surveys probably was more 

representative of marine influences than freshwater runoff. Sulfate and chloride concentrations, 

both of which are present in seawater in much 

larger concentrations than in freshwater, were elevated. Calcium, magnesium, and potassium concentrations also were detected during both 

surveys and would be expected to be somewhat 

lower when conditions are dominated more by 

freshwater inflow.

The herbicide 2,4-D was detected in surface water during both surveys. Other organic 

compounds were not detected in surface water. 
27

Mercury and chromium were detected in surface 

water at all three sites during the 1981-82 survey, 

but were below laboratory reporting levels 

(LRL’s)’s during the 1999-2000 survey. In bottom material, chlordane, PCB’s, DDT, and DDE 

were detected. DDT concentrations decreased in 

the bottom material at Bayou Segnette near Barataria from 1981-82 to 1999-2000. DDE, a degradate product, increased at this site, indicating that 

over time, DDT concentrations are decreasing in 

bottom material of the Barataria Preserve. PCB’s 

were similar in unchanged concentrations (Bayou 

Segnette near Barataria) or increased (Bayou Segnette 4.6 miles below Westwego) from 1981-82 to 

1999-2000.

Trace elements in bottom material exhibited differing trends. Cadmium concentrations 

consistently decreased by half or more at all three 

sites. Mercury concentrations were consistently 

lower at all three sites in the present survey, but 

the differences from the 1981-82 survey were 

quite small. Arsenic concentrations were comparable for both surveys and did not appear to 

change with time at each site. Chromium concentrations increased at two of the three sites from 

1981-82 to the present survey. At the third site, 

no value was available for the earlier survey. 

Concentrations of copper and nickel increased in 

bottom material at the two sites on Bayou Segnette, but decreased at Kenta Canal northwest of 

Westwego. 

Probable Effects Levels (PEL’s) and 

Interim Sediment Quality Guidelines (ISQG’s) 

concentrations, as tabulated by the Canadian 

Council of Ministers of the Environment, were 

used to assess the probability of biological 

impairment in the Barataria Preserve. PEL’s are 

concentrations of a chemical at or above which 

some biological impairment is likely. ISQG concentrations are those at or below which biological impairment is unlikely. Concentrations of 

2,4-D and trace elements, when detected in surface water in the 1981-82 and 1999-2000 surveys, were substantially lower than levels at 

which biological impairment could be expected. 

Concentrations of organic compounds in bottom 

material in both surveys were at most less than 25 

percent of PEL’s, and usually much lower. 

Arsenic, cadmium, copper, and lead concentrations in bottom material were generally slightly 

above or lower than ISQG concentrations in both 

surveys, although arsenic was as high as 53 percent of PEL’s at one site in the 1999-2000 survey. All other trace elements in bottom material 

collected in both surveys were present in concentrations lower than ISQG concentrations.

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