Environmental Atlas of the Lake Pontchartrain Basin

Environmental Status and Trends - Status and Trends of the Lake Pontchartrain Basin

• Environmental Status and Trends
• Pleistocene Terraces Region
  • Florida Parishes Area
• Marginal Deltaic Basin Region
• Mississippi River Deltaic Plain Region

Historically, the Pleistocene Terraces in Louisiana have been referred to as the Florida Parishes. These include the parishes of St. Tammany, Tangipahoa, Livingston, Washington, St. Helena, East Baton Rouge and East Feliciana. Here, due to the abundance of well-drained land, the pressure from development and other land use changes is greater than elsewhere in the Basin. Consequently, the populations of the Florida Parishes are growing faster than anywhere else in the Basin, according to 1999 U.S. Census Bureau statistics (see Population Character of the Lake Pontchartrain Basin). St. Tammany, with a growth of 33.5%, has been the fastest growing parish in Louisiana for more than a decade. The population of Livingston Parish has experienced a growth almost as rapid during this time. Land use has changed from agricultural and forest to suburban residential and commercial (see Agricultural Character of the Lake Pontchartrain Basin).

The population of St.Tammany Parish is currently approaching 200,000. The increasing numbers are creating tremendous development pressure, suburban sprawl, increased traffic congestion and environmental degradation. Recognizing the need for planned and sustainable growth, the St. Tammany Parish Government initiated the New Directions 2025 - St. Tammany Parish Comprehensive Plan. As part of this planning initiative, the status of St.Tammany Parish's natural vegetative types has been analyzed by the Louisiana Natural Heritage Program of the LDWF (Table 1, below). These vegetative types are divided into Aquatic, Wetland and Upland categories. Of the five upland communities and sixteen wetland communities, all are in a state of decline. In the Aquatic category, submersed estuarine grass beds appear to be slowly increasing in area, while floating and submersed vegetation is estimated to be stable. Some of the habitats classified as Wetland are located in the coastal wetland fringe of the north shore, which is part of the Marginal Deltaic Basin region and not in the Pleistocene Terraces region.

According to EPA data, the water quality of the rivers and streams of the Florida Parishes is seriously impaired. None of the sub-basins in this part of the Lake Pontchartrain Basin fully meets EPA's designated use standards, and Bayou Liberty has a fish-consumption advisory for mercury.

All except the Tangipahoa watershed are ranked by the EPA's IWI as having more serious overall water quality impairment, but lower vulnerability (see Water Quality). The Tangipahoa is ranked as having less serious water quality impairment and lower vulnerability, while the Amite River is ranked as having more serious impairment and higher vulnerability. The Tangipahoa was the first river on the north shore of Lake Pontchartrain to receive a primary contact advisory because of high bacterial counts. In the past ten years, the water quality has significantly improved due to measures implemented to reduce sources of bacterial contamination. Recreation activities such as swimming and tubing are likely to resume soon on the Tangipahoa River. However, at this time there are still primary contact advisories for the Tangipahoa, Tchefuncte and Bogue Falaya Rivers, all of which are popular recreation sites.

The Florida Parishes are ecologically, as well as geologically, distinct from the other regions of the LPB. There is a rich diversity of habitat types within this region as Table 1 illustrates. The Louisiana Nature Conservancy also recognizes this attribute and has created five nature preserves in this region. The five Florida Parish preserves are: Lake Ramsay, which protects the last remaining pine savannah habitat in the region; Abita Creek Flatwoods, which contains a variety of critical habitats and 24 species of rare plants, including the endangered Louisiana quillwort; Charter Oak, which protects a 160-acre bayhead swamp; Talisheek Pine Wetlands, which protects pine wetland habitat and provides habitat for the federally threatened gopher tortoise; and Pushepatapa Creek Preserve, the only officially protected site for a state-rare plant, the mountain laurel.

Table 1: Status of vegetative types in St. Tammany Parish Vegetative Type Abundance/Status Trend Causes Notes Aquatic Submersed Estuarine Grassbeds Very rare May be slowly increasing Improving water quality benefitting grassbeds Restricted to shallow brackish water near north shore of Lake Pontchartrain Fresh Floating/Submersed Vegetation Common Stable     Wetlands Fresh Marsh Rare Stable/very slowly declining Saltwater intrusion   Intermediate Marsh Common Stable/very slowly declining   Restricted to marsh zone on north shore of Lake Pontchartrain and mouth of Pearl River Brackish Marsh Uncommon Stable/very slowly declining     Hillside Seepage Bog Exceedingly rare Declining Fire suppression diminishing habitat   Bald Cypress/Bald Cypress-Tupelo Swamp Common (second growth) Slowly declining   Occupies floodplains of large, permanent streams Pond Cypress/Blackgum Swamp Rare Slowly declining   Old growth very rare Bottomland Hardwood Forest Common (second growth) Slowly declining   Old growth very rare Small Stream Forest Common (second growth) Declining Loss due to clearing and commercial forestry Old growth very rare Bayhead Swamp Common (poor quality) Declining Loss due to drainage and habitat conversion High-quality examples rare. A major secondary forest type in southeastern St. Tammany Slash Pine-Pond Cypress/Hardwood Forest Critically imperiled Declining Loss due to fire suppression and habitat conversion Once major secondary forest type in southeastern St. Tammany. Less than 2,000 acres remain in natural state. Slash Pine/Wiregrass Rare Probably declining   Restricted to narrow marsh fringe zone in flatwoods region. Large areas recently incorporated in Big Branch National Wildlife Refuge. Gum Pond Uncommon Slowly declining   Old growth very rare Shrub Swamp Uncommon Slowly declining     Forested Seep Rare Declining Loss due to habitat conversion Restricted to sandy fire protected of uplands of northern St. Tammany. High quality examples rare. Longleaf Pine Flatwood Savannah Rare Declining Loss due to fire suppression and habitat conversion Once major secondary forest type in southeastern St. Tammany. Less than 3,000 acres remain in natural condition. Uplands Hardwood Slope Forest Very Rare Declining   Restricted to hilly uplands of northeastern St. Tammany. High-quality examples rare. Mixed Hardwood-Loblolly Forest Uncommon (second growth) Declining   Old growth very rare. Once a major secondary forest type in parish. Still present along intermittent stream bottoms and fire-protected flatwoods. Shortleaf Pine/Oak-Hickory Forest Critically imperiled Declining Loss due to fire suppression and habitat conversion Once fairly common on upper steep slopes, finger ridges and peninsulas in longleaf pine uplands. Less than 1,000 acres remain in natural condition. Longleaf Pine Flatwoods Critically imperiled Rapidly Declining Loss due to fire suppression and habitat conversion Once major secondary forest type of pine flatwoods in south-eastern St. Tammany. Less than 3,000 acres remain in natural condition. Upland Longleaf Pine Forest Critically imperiled Rapidly Declining Loss due to fire suppression and habitat conversion Once a dominant forest type of hilly uplands of parish. More than 100,000 acres 100 years ago. Less than 5,000 acres remain. No old growth remains.

Table 1: Status of vegetative types in St. Tammany Parish (source: Louisiana Department of Wildlife and Fisheries, 1999 and St. Tammany New Directions 2025 web site.