Jefferson Parish, Louisiana
A Louisiana town elevates homes after Hurricane Katrina
Jefferson Parish, Louisiana invested nearly $2.4 million in elevating 23 homes since Hurricane Katrina. When Hurricane Isaac struck the parish in 2012, none of these homes were flooded, avoiding an estimated $2.2 million in losses. Although the losses avoided were less than the project's costs, the losses avoided estimate accounts for just one flood event in an area with a history of major storms. Indeed, Tropical Storm Cindy affected the Parish in June 2017, and although the losses avoided have not been tallied, it is expected that the losses-avoided ratio will continue to increase significantly over time.
Photo by Mark Wolfe - FEMA
If the 23 homes had not been elevated prior to Hurricane Isaac, each would have flooded above the main-floor level. The properties that would have experienced the highest levels of flooding (up to 3.4 ft) also showed the highest benefit-cost ratios (up to 2.4). With Tropical Storm Cindy, local officials believe homes would have been flooded had they not been elevated. Jefferson Parish ordinances require that property owners must elevate homes to the base flood elevation (BFE) or above when building new homes or, if certain criteria are met, when a home is rehabilitated.
The average cost per property of elevating the 23 homes was $102,663. According to a local floodplain management expert, the community's industries, including fisheries and oil production, benefit from the maintenance of a local population, which is possible only if homes are rebuilt, elevated or otherwise made safe from flooding. Mitigation officials highlight that if shrimpers have to live 20 miles from work, they are not able to run their businesses as effectively.
Benefits of mitigation
It is challenging to quantify all the benefits of the parish’s mitigation efforts
The community faced challenges in demonstrating positive benefit-cost ratios (BCRs) for some projects, owing to the difficulty of quantifying other gains, such as environmental and social benefits. It is often challenging to demonstrate the additional benefits (other than avoiding damage to buildings) from, for example, building a levee around a small town, but those benefits nevertheless exist.
Such additional benefits include growth in local industry, the maintenance of a local population and local businesses to support that population, and the presence of facilities for tourists, such as hotels and restaurants.
"Losses were prevented [from Tropical Storm Cindy]. Had the houses been on the ground then they would have had a few inches of water in them."
"Having a long-term flood mitigation strategy will help to protect the community and its citizens against future storms," says Michelle Gonzales
Additional flood mitigation efforts will continue in the community, based in large part on a state mitigation master plan for the coast. In July 2017, 60 houses were approved for elevation in the Parish, mostly in coastal areas. Almost every repetitive loss structure that appears on FEMA’s list have been elevated or mitigated, so now the Parish is turning to structures that are at-risk, but not considered repetitive-loss properties. However, in the short term, such projects may struggle to gain state funding, as they are low in the priority list but their flood risk must be addressed. Besides elevations, there are other projects in the design phase, such as a floodwall along the Barataria Bayou that would further reduce flood risks.
Flood-prone neighborhood is converted into a park
Riverine flooding, Flash flooding