St. Bernard Parish, LA
Hurricane Katrina, the MRGO, and Flood Zones in St. Bernard Parish
Few places in the country have a flood-risk story as specific and well-documented as St. Bernard Parish's: a single Army Corps shipping canal, built decades before Katrina, that research and litigation later found had turned an already-dangerous storm into a catastrophic one here.
This page covers what's specific to St. Bernard Parish. For the general explanation, see the national guide.
What happened during Katrina
Hurricane Katrina made landfall in southeast Louisiana in August 2005, and St. Bernard Parish experienced some of the most catastrophic, near-total flooding of any community affected by the storm -- the overwhelming majority of the parish's homes and structures took on significant floodwater, and the damage displaced most of the parish's population, with rebuilding continuing for years afterward. St. Bernard's experience became one of the most closely studied examples nationally of how storm surge, levee design, and coastal wetland loss can combine to produce catastrophic flooding.
The MRGO: how one shipping canal became central to the story
The Mississippi River Gulf Outlet (MRGO) was built by the US Army Corps of Engineers in the 1960s as a shorter shipping route connecting the Gulf of Mexico to the Industrial Canal in New Orleans, cutting through wetlands east of the city and along St. Bernard Parish's edge. Over the following decades, the canal's wake erosion widened it well beyond its original design, destroying large areas of surrounding cypress swamp and marsh that had previously helped buffer storm surge before it reached populated areas. During Katrina, post-storm engineering studies and federal litigation found that MRGO functioned as a 'funnel,' channeling and amplifying Gulf storm surge directly toward St. Bernard Parish and the adjacent Lower Ninth Ward of New Orleans, contributing significantly to the catastrophic flooding both areas experienced.
What changed afterward
In the years following Katrina, the federal government deauthorized MRGO for continued deep-draft shipping use and closed off the canal's Gulf-facing end with a rock closure structure, specifically to stop the surge-funneling effect and to allow the surrounding wetlands to begin recovering. This closure is a durable, structural fact about the region's current flood-protection setup, not an open engineering debate -- but this page does not assert the current condition of that structure, the current pace or extent of wetland recovery in the former MRGO corridor, or the final resolution of the extensive litigation that followed Katrina over the Corps' MRGO-related liability, since those specifics require direct, current confirmation.
What this means for evaluating a parcel here today
The most important practical takeaway is this: St. Bernard Parish's post-Katrina flood-protection picture is substantially different from its pre-Katrina picture, both because of the MRGO closure and because of broader levee and flood-protection investment across the greater New Orleans area since 2005 -- but 'substantially different' does not mean 'risk-free,' and this page cannot tell you the current flood-zone designation for any specific parcel. Pull a current FEMA flood-zone determination directly, and ask St. Bernard Parish Government and the applicable local levee district or flood protection authority about current levee elevations and any base-flood-elevation or rebuilding requirements that apply to the specific parcel you're evaluating -- these have been revised multiple times since 2005 and should never be assumed from an older summary, including this one.
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Connect with a local land specialistSources
- Hurricane Katrina — National Hurricane Center / NOAA (accessed 2026-09)
- Mississippi River Gulf Outlet (MRGO) Ecosystem Restoration — US Army Corps of Engineers, New Orleans District (accessed 2026-09)
- National Flood Hazard Layer / Flood Map Service Center — Federal Emergency Management Agency (FEMA) (accessed 2026-09)
- St. Bernard Parish, Louisiana — 64 Parishes (Louisiana Endowment for the Humanities) (accessed 2026-09)
Last reviewed 2026-09