River Reintroduction into Maurepas Swamp 

PO-29 

February 2005 

Project Background 

In early 2001, the Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA or Breaux Act) Task

Force approved a project that will return a minimum of 1,500 cubic feet/second (cfs) Mississippi River flow to the 

Maurepas Swamp, restoring swamp hydrology, increasing sediment and nutrient loading, and reinvigorating the

Maurepas Swamp. Over 36,000 acres of wetlands will benefit from this re-introduced river flow. The 

Environmental Protection Agency (EPA) is the lead federal agency for the Maurepas project. The State of 

Louisiana shares in the cost of all Breaux Act projects, typically at a rate of 15% State to 85% federal. The State 

partner is the Louisiana Department of Natural Resources (LDNR). With assistance from St James and St John

Parishes and LDNR, EPA and the Governor’s Office of Coastal Activities have hosted numerous public meetings

with community residents and Maurepas Swamp users and stakeholders. Valuable input has been gained during

these meetings and has aided in bringing this project to a point where engineering and design are now underway. 

Hydrodynamic Computer Models: 

Hydrodynamic computer models of the residential areas from

the Mississippi River to Airline Highway will aid in assessing 

the impacts to local drainage from the reintroduction channel. 

URS, an engineering firm under contract to the State of 

Louisiana, is presently calibrating and verifying the hydraulic 

computer models. These models will be used to determine 

where the water will flow once diverted from the Mississippi

River. The model will also determine the impacts the 

reintroduction will have on local drainage. In summary the

bathymetric or hydraulic portions of the survey, along with the 

number of ridges/structures and short-circuit flow patterns 

discovered in the swamp area, required a much more detailed 

two dimensional (2D) grid or surface and a two dimensional 

computer model to ensure detailed and accurate results. The 

2D model is now being run on a 16-computer cluster to capture

all of the necessary detail. This additional 

detail has lengthened the schedule beyond

what was originally anticipated, but the 

computer simulations should provide more 

detailed and accurate results that will 

move the reintroduction project forward. 

The model will also be able to provide 

analysis far into the future that can be used

for preserving and restoring this precious

resource within the River Parishes. 

A meeting will be held later this year to

present the findings and to discuss the 

project with the public. 

Chris Williams, LDNR, (225) 342-7549;

chrisw@dnr.state.la.us 

LSU Studies of the Maurepas Swamp Recently Completed: 

Researchers at Louisiana State University recently completed studies of hydrology (water movement), water 

quality, and ecology of the Maurepas Swamps. These studies were continuations of earlier studies conducted in

2000-2001 by this same group of scientists and engineers. Data collected during 2000-2001 reflected the unusual

drought conditions during that time, so this latest study (data collected 2002-2003) reflects more typical 

conditions. The group developed a more sophisticated computer model of hydrology than the one they developed 

in the earlier studies, which they used to confirm answers to questions posed using the previous hydrology model,

and to answer additional questions about the possible effects of reintroduction of Mississippi River water into the 

swamps. This model reinforced earlier predictions that reintroducing Mississippi River water will reduce salt 

water intrusion into the swamps, which can kill or weaken the cypress and tupelo trees. The model also reinforced 

earlier predictions that nutrients in the river water would be almost completely taken up in the swamp before the 

water reaches Lake Maurepas- in turn, supporting the earlier prediction that reintroduction of Mississippi River 

water would not cause algal blooms in Lake Maurepas. The researchers also developed a new computer 

ecological model of the swamp, called SWAMPSUSTAIN. The model estimates the time it will take a 

reintroduction of Mississippi River water into the swamp to result in target swamp elevations considered necessary 

for long-term sustainability of the swamp. Remember that swamp elevations are currently very low, so that trees 

are flooded almost constantly which is very harmful to them, and that the swamp continues to lose elevation due to
subsidence. The model predicts that between 5,000 and 10,000 acres of the Maurepas swamp can be restored to

sustainability within 50 years if average yearly diversion discharges greater than 1,000 cubic feet per second are 

maintained. The computer hydrodynamic modeling and hydrologic data collection done by LSU were conducted

primarily to develop techniques for predicting long-term ecological benefits and impacts of the Maurepas

reintroduction to the swamp and lake. The URS modeling is being conducted to determine whether the 

reintroduction would affect local drainage, as well as to verify results of other models regarding where

reintroduction water will flow. 

Environmental Impact Studies

Begin: 

Following the initial project scoping activities conducted

in December 2002 and January 2003, EPA is beginning the 

preparation of the Environmental Impact Statement (EIS) 

for the proposed project as required under the National

Environmental Policy Act. Currently, studies include an

assessment of the possible risk of hazardous materials in 

the proposed construction corridor, and to a lesser extent, in

the entire project area. This work is necessary to ensure 

that the project would not increase environmental 

exposures as a result of any hazardous materials, should 

any of these materials be present within the project area. 

Also, more comprehensive studies of potential water 

quality impacts of the proposed reintroduction of

Mississippi River water into the Maurepas Swamps are 

being started. Private environmental consulting 

companies under contract to EPA are 

conducting both of these studies. Shortly, EPA

expects to begin other studies required to

develop the EIS, as well as to meet requirements 

under the Endangered Species Act, and the

Magnuson-Stevens Fishery Conservation and 

Management Act, including studies of

threatened and endangered species and Essential 

Fish Habitat. Pamela Mintz, EPA; (214) 665-

8334; mintz.pamela@epa.gov 

 

 

For further information on the status of the Maurepas project, visit the following websites:

http://www.epa.gov/earth1r6/6wq/ecopro/em/cwppra/index.htm or http://www.lacoast.gov/projects/list.asp 

• Kenneth Teague – Environmental Protection Agency Project Manager; (214) 665-6687

teague.kenneth@epa.gov

• Chris Williams, P.E. – Louisiana Department of Natural Resources Project Manager; (225) 342-7549

chrisw@dnr.state.la.us 

• Pamela Mintz – Environmental Protection Agency NEPA Coordinator; (214) 665-8334

• mintz.pamela@epa.gov 

• Patty Taylor, P.E. – Environmental Protection Agency Project Engineer; (214) 665-6403

taylor.patricia-A@epa.gov

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