Overview of Selected Parishes’ Freeboard, Fill, and Open Space Rules and Projects within Louisiana’s Region Seven Watershed

Executive Summary

As coastal erosion and the threat of major hurricanes and other flooding events continue to threaten Louisiana, parishes have begun to adopt jurisdiction-specific approaches to mitigating those risks. The establishment of freeboard requirements, no-net fill practices, and the incorporation of green stormwater infrastructure (GSI), such as open spaces and native vegetation, are three major ways to prepare for and mitigate flooding. 

This brief entry provides a non-exhaustive overview of some of the ways five Louisiana parishes are using these approaches: Ascension, St. Bernard, St. John the Baptist, St. Tammany, and Tangipahoa. Elevation and fill requirements in the parishes only apply to constructions in the 100-year Special Flood Hazard Area (SFHA) or the floodway within it.1 Fill and other encroachments into the floodway are generally prohibited absent a showing that flood levels in the community would not be raised by that encroachment.2 

Note, these regulatory provisions discussed below are accurate through April 2022. 

 

Ascension Parish 

Ascension Parish requires all structures within the SFHA to be elevated two feet above base flood elevation (BFE).3 Mobile homes must also be elevated to two feet above BFE.4  

The parish uses a Flood Overlay Zoning District to regulate development in the floodplain.5 Legislative commentary to the Flood Overlay District Ordinance clarifies that subdivision development has occurred in the floodplain, and the overlay district is meant to discourage residential development in those high-risk areas by requiring elevation certificates before allowing such development.

Inside the floodplain, fill used for elevation cannot exceed 36 inches in average height and must come from the same property or watershed.6 A no-net fill provision applies for any fill below BFE (any fill inside the floodplain under BFE must be offset by the removal of fill elsewhere in the floodplain). Fill must be kept 10 feet away from property lines. Further, the parish encourages the conservation of environmental features like open spaces through conservation districts and single-family zoning in rural areas that protect land from development.7 

 

St. Bernard Parish

The parish requires that structures be elevated 18 inches above BFE for all development in the SFHA, though nonresidential development can alternatively be floodproofed.8 

New developments are required to have a front yard setback — a buffer between development and the nearest public road.9 No more than 40 percent of the space occupied by the setback can be covered by impervious pavement, and “[a] green area of living planted materials shall be provided within all other areas of the required front yard area that are not paved.”10 The parish is also piloting the North Arabi Resilience District, meant to encourage green infrastructure, open spaces, parks, and other features of resilient neighborhood development.11 

 

St. John the Baptist Parish

All new development in the parish’s SFHA must be elevated to or above BFE, though nonresidential development can be floodproofed instead of elevated to that height.12  

In addition, the parish updated its ordinances to promote stormwater management and is incorporating GSI into several parish development projects. As of 2020, the Code of Ordinances has been updated to include a stormwater management chapter.13 The new ordinances require new development in the parish to have a stormwater management plan for pre- and post-construction water flows. The management plans must be designed to reduce pollution and be supported by best management practices (BMPs), with priority given to GSI, pervious pavement, bioretention areas, and other practices that promote infiltration and retention.14 

Further, the parish is revitalizing two areas, Belle Terre Boulevard and the Airline and Main area. The Belle Terre project is a complete streets project meant to stimulate economic activity in the area and incorporate GSI like bioswales and retention basins.15  The Airline Highway/Main Street project includes green infrastructure and transportation enhancements as nonstructural flood risk reduction measures.16  

 

St Tammany Parish 

According to the parish’s flood hazard standards, all development within the SFHA must be built at or above BFE, though nonresidential development can be floodproofed instead of being elevated to that height.17  

Spatially, the parish also uses Areas of Special Concern, which are parish-designated Critical Drainage Areas or places designated by the parish as having critical importance for drainage. Although located in Flood Zone C, these are areas with the strictest development limitations, where fill is prohibited and the lowest finished floor must be 24 inches above the crown of the road.18 Further, the St. Tammany Parish Ordinance requires all homes that are not in a SFHA, Area of Special Concern, Critical Drainage Area, or lot greater than 90 feet be 12 inches above the crown of the road or top of curb fronting the home, whichever is greater.19 There is an additional freeboard requirement in the Pearl River Basin that mandates all homes located in an Advisory BFE Area to have a finished floor elevation of one foot or greater above the BFE.20 

St. Tammany’s current comprehensive plan, New Directions 2025 (ND 2025), states that existing regulations do not sufficiently protect green spaces, which is one of the parish’s most valuable assets.21 The plan thus calls for requirements that portions of all new development set aside green space that shall be conserved in perpetuity. ND 2025 also embraces the use of green spaces for their aesthetic benefits, such as using riparian buffers as a “scenic” measure that serves a management purpose while adding to the parish’s aesthetic. Parish design standards also require that subdivisions with more than 25 lots set aside green space of not less than 580 square feet per lot.22 

The parish’s landscaping and tree preservation ordinance outlines regulations to prioritize trees and landscape features in development, and requires a landscape and tree preservation plan to be submitted for any project requiring a landscape permit.23 The tree preservation ordinance also includes a tree bank program, where the parish may assess fees for those who negatively affect or decrease tree canopy cover through new development or redevelopment.24   

 

Tangipahoa Parish

Tangipahoa Parish updated its land use code as recently as 2020. In the new code, the parish requires structures to be elevated to at least 12 inches above BFE, though nonresidential development can alternatively be floodproofed instead of elevated to that height.25  

Developments must meet a no-net fill requirement and the parish’s ordinance limits fill to two feet above existing ground elevations for areas under proposed roadways and driveways.26  

All developments are also required to preserve a 25-foot greenspace buffer. In a Special Use Residential Commercial Development, such as a manufactured home or RV park, a stormwater management area of 20 percent of the total development area is required. The greenspace buffer can be a part of this management area. 

 

Publication Date: May 18, 2022

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