U.S. Department of the Interior a U.S. Geological Survey

U.S. Geological Survey

Programs in Louisiana 

Shoreline erosion and

wetland loss

Sediment and water

pollution

Saltwater intrusion

Shell dredging

Freshwater diversion

Agriculture runoff

Sewage/municipal runoff

Saltwater intrusion

Mississippi

Major issues

EXPLANATION

90°

30°

LAKE

MAUREPAS

LAKE

BORGNE

LAKE

PONTCHARTRAIN

River

LOUISIANA

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0 10 KILOMETERS

New

Orleans

Study

area

Bonnet Carre'

Spillway

Louisiana has abundant natural 

resources that include the lower Mississippi River, which is the largest river system in the United States. The State’s 

unique geography and associated ongoing 

geologic processes are environmentally 

significant; however, these factors can 

contribute to coastal erosion, wetland loss, 

saltwater encroachment into surface and 

ground waters, land subsidence, and 

flooding.

Solutions to these varied and challenging earth science problems can be aided 

by the scientific approach of the U.S. Geological Survey (USGS), which has provided unbiased, technically sound earth 

science information for more than 100 

years. This Fact Sheet is designed to 

inform citizens about current USGS programs in Louisiana that address relevant 

earth science needs and issues and provide 

scientific understanding and information 

on which decisions can be made to minimize and mitigate the effects of natural 

hazards and human activities on critical 

natural resources.

Lake Pontchartrain Basin 

Scientific studies recently begun by the 

USGS indicate that several key natural 

processes and human-induced environmental factors are directly affecting the 

health of Lake Pontchartrain (fig. 1), which 

is one of America’s largest estuaries. The 

USGS, at the request of the U.S. Congress, 

began an evaluation of the environmental 

issues that face the region and developed a 

multiyear strategic plan to collect the scientific information needed to address them. 

The specific environmental issues 

addressed by the study include contamination of sediment and water by chemicals 

from urban and agricultural sources, lakeshore erosion and loss of grass beds, intrusion of saltwater from canals and navigable 

waterways into aquifers, and effects of past 

long-term commercial shell dredging.

The USGS, in cooperation with Louisiana State University (LSU), is documenting the geologic framework of the 

lake, shoreline contours, and contaminated sediments; developing a computer 

circulation model; and providing interim 

results to the public and the planners 

involved in efforts to restore and protect 

the Lake Pontchartrain Basin.

In 1984, the U.S. Army Corps of 

Engineers (USACE) was authorized to 

construct a diversion canal from the Mississippi River to allow water to flow into 

Lake Pontchartrain. In response to the 

concerns of some citizen groups about 

the effects this would have on Lake Pontchartrain, a multiagency reanalysis committee, which comprises Federal, State, 

and private representatives, was formed. 

The USGS helped the committee in the 

design of an experimental release of Mississippi River water into the lake through 

the Bonnet Carré Spillway and provided 

technical expertise on determining the 

potential effects of this release. Dye studies were conducted and physical conditions of the lake were monitored to 

determine potential mixing patterns. The 

USGS also collected water-quality and 

other hydrologic information to evaluate 

the effects of the diversion on the aquatic 

health. 

Coastal Restoration and 

Wetlands Monitoring

The coastal marshes and tidal wetlands 

of Louisiana's coast and the barrier islands 

that protect them form one of the world's 

most productive ecosystems. Louisiana has 

25 percent of the vegetated wetlands and 

40 percent of the tidal wetlands in the 48 

contiguous States. However, the Gulf 

Coast of Louisiana is eroding faster than 

any other coastal area of the world. Every 

year, Louisiana loses as much as 40 square 

miles of land—an area nearly the size of 

Washington, D.C. Some of this land loss 

can be traced to human activity, but much 

of it can be traced to the forces of nature, 

Index of Subjects

Lake Pontchartrain Basin

Coastal Restoration and Wetlands 

Monitoring

Mercury in Fish

Wetland, Forest, and Animal Ecology

Surface-Water Resources in St.Tammany 

Parish

Topographic Mapping

Sharing Geospatial Data

Saltwater Encroachment Near Baton Rouge

Digital Raster Graphic Program

Collection of Hydrologic Data

Center for Coastal Geology

Statewide Real-time Flood Monitoring

Earth Science Information Center

Figure 1. Environmental issues that face 

Lake Pontchartrain.

Earth Science in the Public Service
Revisions in progress

Completed revisions

Previous maps

EXPLANATION

which include land subsidence caused, in 

part, by compaction of the Mississippi 

River Delta sediments and large storms 

that strike the area about every 5 years.

Since 1984, the USGS has worked 

closely with various Federal, State, and 

local agencies to document coastal erosion 

and wetland loss. USGS studies have 

included applied research and monitoring 

of basic geologic and hydrologic variables 

to document the causes of and processes 

responsible for the widespread devastation. 

Results of these studies are an integral part 

of the Federal and State Wetlands Task 

Force, which is spending $40 million per 

year in restoring and preserving Louisiana's 

valuable coastal resources. 

USGS scientists play key roles in the 

design of monitoring programs for the 

Comprehensive Coastal Wetlands Planning, Protection, and Restoration Act. They 

serve as technical consultants to other U.S. 

Department of the Interior agencies, the 

USACE, the U.S. Environmental Protection Agency (USEPA), and the Office of the 

Governor of Louisiana on matters that concern geologic, water-quality, and other 

hydrologic issues, as well as the erosion of 

barrier islands and wetlands loss. 

The USGS, in cooperation with the 

Louisiana Department of Natural 

Resources, has installed and operates 19 

surface-water monitoring sites at key locations along the Louisiana coast. Data collected at these sites provided Louisiana 

with vital information on Hurricane 

Andrew as it tracked along the coast. The 

data also are used to manage freshwaterdiversion and coastal-restoration projects 

by the State of Louisiana and the USACE.

Mercury in Fish

In 1994, the USGS, in cooperation with 

the Louisiana Department of Environmental Quality, began a study to determine the 

presence and concentration of mercury in 

selected fish, water, and bottom sediments 

from streams and lakes throughout the 

State. Spanish moss and tree lichens, which 

are indicators of atmospheric sources of 

pollution, also were studied. Study sites 

were selected jointly by the USGS and the 

State on the basis of historical water, bottom sediment, and tissue data in both agencies' data bases and the recreational and 

financial importance of large commercial 

fisheries. Results of sampling have been 

provided to the Louisiana Department of 

Health and Hospitals for review and possible health advisory consideration. Four 

samples indicated mercury levels in fishtissue that were above USEPA (1.0 part per 

million) and State (0.5 part per million) 

limits.

Wetland, Forest, and Animal 

Ecology

The USGS Biological Resources Division (formerly the National Biological Service) conducts research throughout 

Louisiana on wetland, forest, and animal 

ecology.

The National Wetlands Research Center 

(NWRC) at the University of Southwestern 

Louisiana research park in Lafayette uses 

geographic information systems (GIS) and 

remote sensing to monitor wetland change 

and to plan restoration. Research includes 

developing wetland-restoration techniques 

in Yazoo National Wildlife Refuge and 

Caddo Lake and studying functions in the 

Kisatchie National Forest; developing 

models to predict habitat changes at the 

Felsenthal National Wildlife Refuge and 

other sites; determining the effectiveness of 

management practices on restoration and 

maintenance of coastal wetlands; and 

studying collaboratively how private industries’ water-management affects saltwater 

and freshwater species. NWRC scientists 

evaluate planting procedures, research controlling invasive species, study the effects 

of fire management, and identify natural 

community processes along the Gulf 

coastal prairie. Migratory-bird researchers 

study habitat, behavior, productivity, and 

landscape feature relations.

Two Cooperative Research Units, one at 

LSU and one at Grambling State University, in collaboration with other agencies, 

research bird migrations and habitat use, 

fishery-resource management and use, and 

effects of weather patterns on wildlife.

Surface-Water Resources in 

St. Tammany Parish

The northern shore of Lake Pontchartrain and especially St. Tammany Parish 

have undergone extensive population 

growth in the last decade. Public officials 

and private citizens are concerned about the 

effects of this growth on the quality of surface water in the parish and Lake Pontchartrain. Historically, this area has been highly 

productive for freshwater and saltwater 

fisheries. However, the capability of the 

surface water in this area to assimilate everincreasing amounts of wastes from point 

(sewage-treatment facilities) and nonpoint 

(residential and agricultural fertilizers) 

sources has definite limits. 

In response to these concerns, the 

USGS, in cooperation with St. Tammany 

Parish, recently investigated the effects of 

population growth on water quality in 

streams within the Parish. This information 

can be used to make decisions regarding 

current and future wastewater management.

Topographic Mapping

Among the most popular and versatile 

products of the USGS are its 1:24,000-

scale topographic maps (1 inch on the map 

represents 2,000 feet on the ground). These 

maps depict basic natural and cultural features of the landscape, such as lakes and 

streams, highways and railroads, boundaries, and geographic names. Contour lines 

are used to depict the elevation and shape 

of terrain. Louisiana is covered by 877 

maps at this scale, that are useful for civil 

engineering, land-use planning, naturalresource monitoring, and other technical 

applications. These maps have long been 

favorites with the general public for such 

uses as hiking, camping, exploring, and 

fishing expeditions. Revision work in 

progress to update the information on 

selected 1:24,000-scale topographic maps 

for Louisiana is shown in figure 2.

Figure 2. Revision of 1:24,000-scale 

topographic maps for Louisiana.
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Saltwater 

encroachment

Saltwater front for

specified year

Monitoring well

Pumping center

for public supply

Saltwater area

BATON

ROUGE

Study area

Index Map

LOUISIANA

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The USGS and the Louisiana Department of Transportation and Development 

(DOTD) have long worked together to 

provide the most current and accurate 

topographic maps possible. Currently, the 

two agencies have an agreement wherein 

a new digital revision process is used to 

revise existing 1:24,000-scale maps and to 

produce digitized map data for southwestern Louisiana. This new technique allows 

for timely revision of the topographic map 

and generates digital data that can be used 

in GIS.

Sharing Geospatial Data

The Competitive Cooperative Agreements Program (CCAP) was established 

by the Federal Geographic Data Committee through the USGS to help form datasharing partnerships with the non-Federal 

sector. This program provides funding to 

State and local government agencies, academia, and the private sector to encourage 

resource-sharing projects through the use 

of technology, networking, and interagency coordination. The LSU Center for 

Energy and Environmental Resources has 

been funded by CCAP to establish a 

National Spatial Data Infrastructure clearing-house node for Louisiana. The clearing house is a distributed, electronically 

connected network of geographic and cartographic data producers, managers, and 

users. The network allows users to find the 

data they need, evaluate the data for their 

application, and obtain the data as economically as possible.

Saltwater Encroachment Near 

Baton Rouge

Because of large withdrawals from the 

aquifer system in the Baton Rouge area, 

ground-water flow patterns have been 

altered over the years. Saltwater now 

encroaches into formerly freshwater areas, 

which could destroy their usefulness for 

public and most industrial supplies. The 

aquifers in the Baton Rouge area supply 

water for about 360,000 people and large, 

economically critical industries. 

A recent study by the USGS, in cooperation with the DOTD and the Capital 

Area Ground Water Conservation Commission, showed that the quality of ground 

water at two public supply pumping centers will soon be affected by saltwater 

encroachment (fig. 3). Local officials are 

concerned about the impending encroachment and are planning strategies that are 

based on results of USGS studies to protect these water supplies. Currently, plans 

are underway at the USGS for expansion 

of ground-water data-collection activities 

to monitor the effects of remedial saltwater-diversion strategies.

Digital Raster Graphic Program

The USGS and the National Park Service (NPS) have established an interagency agreement to produce digital raster 

graphics (DRG’s) for barrier islands along 

the Gulf Coast east of New Orleans. The 

DRG’s are inexpensive digital products, 

scanned from USGS topographic maps, 

that can be used as an accurate base for a 

geographic information system. A private 

company is producing the DRG’s for the 

USGS and participating agencies under an 

innovative Federal/private partnership. 

DRG’s are prepared for all 1:24,000-, 

1:100,000-, and 1:250,000-scale topographic maps that cover the NPS area of 

interest. The DRG’s are available to the 

public on CD–ROM.

Collection of Hydrologic Data

The USGS, in cooperation with more 

than 13 Federal, State, and local agencies, 

collects streamflow, water-quality, and 

ground-water data at sites throughout the 

State. These data are critical for the dayto-day administration and management of 

water resources, determination of the 

extent and severity of droughts, characterization and prediction of floods, and monitoring of the effects of human activities on 

streamflow, ground water, and water quality. These data also are essential to interpretive studies, the results of which are 

used by numerous other agencies to make 

decisions about water issues that affect 

millions of people.

Center for Coastal Geology

In 1988, the USGS Center for Coastal 

Geology and Regional Marine Studies was 

established in cooperation with the University of South Florida. The center conducts a 

wide variety of research on coastal and 

regional marine problems in the States that 

border the Gulf of Mexico. These problems, which are of particular interest in 

Figure 3. Saltwater encroachment in the “1,500 foot” aquifer toward pumping centers.
For More

Information

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U.S. Army Corps of Engineers stations

U.S. Geological Survey stations

EXPLANATION

Gulf of Mexico

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New Orleans

Baton Rouge

Shreveport

Louisiana’s coastal wetlands, include 

coastal erosion, climate change, wetlands 

deterioration, coastal pollution, and hardmineral resources. With increased understanding of these problems, future coastal 

erosion, the fate of wetlands, where polluted sediments accumulate, and the location of economically valuable hard 

minerals can be more accurately predicted.

Statewide Real-time Flood 

Monitoring

Louisiana leads the Nation in property 

damage caused by floods. To reduce future 

losses, the USGS, in cooperation with Federal, State, and local agencies, operates a 

statewide real-time flood monitoring network. Currently, the USGS monitors 101 

USGS and USACE gaging stations 

throughout the State to measure river stage 

and to transmit data directly on a real-time 

basis by means of radio and satellite relay 

technology (fig. 4). During floods, this 

information is passed on to the appropriate 

emergency response agencies and the news 

media through the Louisiana Office of 

Emergency Preparedness.

A flood-tracking map, which was modeled on a hurricane-tracking map, has been 

prepared for the Amite River Basin near 

Baton Rouge. The map was a joint effort 

among the USGS, the Amite River Basin 

Commission, a local television station, and 

other local businesses and was distributed 

through fast-food outlets to the public. People living in potentially affected areas can 

use these maps and the USGS hydrologic 

information provided through the news 

media to make decisions about evacuation 

and protection of personal property.

Earth Science Information 

Center

The USGS Earth Science Information 

Centers (ESIC) provide information about 

the USGS, its programs, products, and 

technological developments to the public. 

The ESIC at the Louisiana Geological Survey (LGS) at LSU in Baton Rouge was 

established under a cooperative agreement 

between the USGS and the LGS. As part of 

the national ESIC network, these offices 

provide information on such earth science 

topics as cartography, geography, digital 

data, remote sensing, geology, geophysics, 

geochemistry, hydrology, geohydrology, 

aerial photography, and land use. The 

offices also have USGS map products 

available for purchase.

USGS State representative

3535 S. Sherwood Forest Blvd.

Suite 120

Baton Rouge, LA 70816

(504) 389-0281 ext. 3107

Fax: (504) 389-0706

Email: dc_la@usgs.gov

Additional earth science

information can be found by

accessing the USGS Home Page

on the World Wide Web at

http://www.usgs.gov/

For more information on

all USGS reports and products

(including maps, images,

and computerized data), call

1-800-USA-MAPS

The USGS provides maps,

reports, and information to help

others meet their needs to manage,

 develop, and protect America’s water,

energy, mineral, biological, and land

resources. We help find the natural

resources needed to build tomorrow,

and supply the scientific understanding needed to help minimize or mitigate the effects of natural hazards

and environmental damage caused

by natural and human activities. The

results of our efforts touch the daily

 life of almost every American.

U.S. Geological Survey

Figure 4. Statewide real-time flood-monitoring network. Fact Sheet FS-018-96