The Lake Pontchartrain Important Bird Area (IBA), an estuarine system, is over 400,000 acres, of which nearly all is open water. Comprised solely of Lake Pontchartrain, this IBA is an enormously important recreational site as it resides within several densely-populated parishes. Three IBAs, West Pontchartrain-Maurepas Swamp IBA to the west, East Delta Plain IBA to the east, and Big Branch-St. Tammany Flatwoods IBA to the north, nearly surround this site.
Lake Pontchartrain has been the focus of several groups working to address threats such as pollution and changes to the ecosystem caused by dredging of clams. The Coalition to Restore Coastal Louisiana and the Lake Pontchartrain Basin Foundation have worked for years reducing these threats. These changes may translate into improved water quality, vegetation, and aquatic life that support bird populations in the lake.
Two other local non-profit organizations developed in response to large Purple Martin roosts on the Lake Pontchartrain Causeway and a nationwide decline of Purple Martin detected in the 1980s. Project Swallow is dedicated to the research and protection of swallows and martins, and Helping Hands, Inc., to the rehabilitation of injured Purple Martins. Success of these groups led Project Swallow to expand in scope and to become incorporated as National Wildbird Refuge, Inc., a non-profit dedicated to creating a sanctuary on the south shore of Lake Pontchartrain for the martins that roost there, along with other birds and wildlife.
A walkway, fencing, and storyboard for the sanctuary were destroyed during Hurricane Katrina. However, the roost structure itself was undamaged, and fencing to protect the birds from traffic was also intact. The fencing is one of the great accomplishments of National Wildbird Refuge, Inc. It has dramatically reduced fatality of Purple Martins ? over 12,000 per year were killed by passing automobiles prior to the installation of the fencing.
The Lake Pontchartrain IBA supports relatively large numbers of wintering waterfowl, including Horned Grebe and Common Loon. Lesser Scaup populations declined in the lake from 1978 to 2002 during a time which they also declined nationwide. However, despite changes in the water quality, salinity and habitat in the lake, tens to hundreds of thousands of Lesser Scaup have persisted at this shallow, estuarine lake. In fact, the highest count in two decades, more than 1 million birds, came in the winter following Hurricane Katrina.
This IBA is frequented by a number of other species. Various gulls and terns, herons, egrets, rails and Black Skimmer can all be found in this site. The IBA also functions as a great stopover site for migrating birds. The lake provides excellent feeding opportunities for birds that prefer open water such as the scoters. Raptors such as Bald Eagles and Ospreys nest and forage in the habitats that surround the lake.
The Brown Pelican was extirpated from Louisiana in the 1960?s, in part due to DDT and other pesticides that entered the Mississippi River from agricultural runoff and chemical spills, weakening egg shells and causing breeding failure. A successful restocking program undertaken in 1968 by the Louisiana Department of Wildlife and Fisheries has restored a strong population in Louisiana. Creation and enhancement of breeding islands has helped maintain the population in the face of habitat loss. While Brown Pelicans do not generally feed on inland lakes, they commonly feed on Lake Pontchartrain in the winter.
While they are on human-built structures, the Purple Martin roosts on the Lake Pontchartrain Causeway each support peak numbers of up to 250,000 martins during the breeding season. The roosts are also active during spring and fall migration and the post-breeding season. These birds feed over the lake and over land in surrounding IBAs. Up to 8 million martins may pass through this site each season during migration.
Urban sprawl from Baton Rouge, the Slidell area, and Metro New Orleans impact this IBA. A serious decline of water quality is a result of untreated sewage as well as dairy farm and urban runoff that enters rivers, bayous, canals, and the lake directly. Conversely, deliberately filtering effluent through wetlands cleans the effluent and stimulates plant productivity, increasing wetland elevation and offsetting subsidence. This type of marsh restoration is practiced by some communities around Lake Pontchartrain.
Submerged aquatic vegetation is disappearing as a result of shoreline hardening projects such as concrete sea walls and riprap levees. Saltwater intrusion is also a concern, altering the habitat and thus altering the food supply available to birds. Algae blooms caused by nutrients coming from the Bonnet Carre spillway and runoff reduce water quality and pose health risks for both people and fish. Litter, especially along the south shore of Lake Pontchartrain, potentially creates health risks for people and animals. Hot weather decreases the amount of oxygen in the lake?s water, resulting in fish kills.
Lake Pontchartrain is recovering from clam dredging which began in the 1950s. Filter-feeding clams clean the lake water and provide a hard bottom for the 12-foot lake. Dredging removed water-filtering capacity and stirred up significant amounts of sediment into the water, shading out sunlight, and damaging seagrass beds and aquatic life. Since clam dredging ended clam populations and native vegetation are increasing and water clarity and quality have improved.
The Mississippi River Gulf Outlet (MRGO), built in 1965, cut a straight, deep, shorter channel from the Gulf of Mexico into New Orleans Inner Harbor. This channel allowed direct influxes of saltwater into the estuary, changing it from a fresher to a more saline condition. Closure of the MRGO began in 2009. Already, the lake is returning to a more natural condition.
Lake Pontchartrain is owned by the state of Louisiana.
Lake Pontchartrain, the only feature in this IBA, is part of the Lake Pontchartrain Basin. The basin is considered an estuarine system; it consists of subtidal habitats and adjacent wetlands that are semi-enclosed by land but have some access to the Gulf of Mexico, resulting in brackish water. The low-energy environment allows appreciable dilution of sea water. The basin's topography ranges from hardwood forests in the north to coastal marshes in the south, with the 630 square mile Lake Pontchartrain as its centerpiece. Rivers, bayous, swamps, hardwood forests, and man-made beaches are all part of the basin.
The lake is essentially a shallow estuarine bay with fairly restricted tidal movement and brackish water. A number of rivers feed into the basin that eventually feeds into the lake, including the Tchefuncte, Tangipahoa, Maurepas, and Blind Rivers. Salinities vary in the lake, with the freshest water near the riverine inflows. Pine flatland and pine savannah environments exist near some of the lake?s banks. Along river banks lie a number of mixed bottomland hardwood forests. Major interchanges between lake water and the Gulf of Mexico occur at the Rigolets and Chef Menteur Pass.
Closure of the Mississippi River Gulf Outlet (MRGO) will return the lake to a less saline condition. The opening of this deep shipping channel in 1965 allowed saltwater from the Gulf to flow directly into the lake, altering salinities and turning the water more saline. Salinity change has altered vegetation in the lake.
This IBA provides the public with recreational activities such as boating, kayaking, sailing, canoeing, fishing, hunting, picnicking, swimming, walking, dog walking, bird-watching and bicycling. The Louisiana Department of Wildlife and Fisheries (LDWF) just added four new artificial reefs to Lake Pontchartrain to create habitat for fish and shellfish. Some commercial fishing, shrimping, oystering, and crabbing occur within this IBA. Some oil and gas operations are also present. During times of extremely high water on the Mississippi River, the Bonnet Carre Spillway may be opened, allowing Lake Pontchartrain to be used for flood control for downstream communities.