Jefferson Parish, Louisiana
A shallow water table limits basements on 44% of Jefferson Parish's mapped land, a higher share than 61% of US counties. Shrink-swell clay limits houses without basements on 27%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 5,852 flood losses here since 2016, under 1% of them in buildings with basements. 62% of homes were built before 1980, against 50% nationally; the median home dates from 1975.
Data as of October 13, 2026 · sources
expansive clay: shrink-swell limits slab homes
high water table: limits basements
in drought, October 13, 2026
of homes built before 1980
Soil under Jefferson Parish
| Expansive clay (limits slab homes) | 27.3% |
| High water table (limits basements) | 43.7% |
| Septic fields very limited | 42.2% |
| Clay swell (LEP, by area) | 14.3% |
| High-swell land (LEP 6%+) | 27.3% |
| Mapped soil | 387,400 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Lafitte | 9% | n/a |
| Kenner | 7% | n/a |
| Schriever | 5% | n/a |
| Clovelly | 4% | n/a |
| Cancienne | 4% | n/a |
| Allemands | 3% | n/a |
How we count · survey areas LA051 (2025-09-05)
What the numbers mean here
Clay swell averages a linear extensibility of 14.3% by land area here, and 27% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 27% of the mapped land.
On 44% of Jefferson Parish's mapped land, soil stays saturated within about 6 feet of the surface for part of the year, which is basement depth.
Rain over the 12 months to August 2026: 52.60 in, 10.89 in below the 1991-2020 average year of 63.49 in.
Drought
0% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 39 of the last 52 weeks; the most was 100% of its area, in 18 weeks, most recently on the May 19, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
5,852 flood losses since 2016, $166.8 million paid. The worst year was 2021, with 3,566. Foundations of the buildings, where recorded: under 1% basements, 72% slabs, 5% crawl spaces, 23% elevated. Median water depth outside the building: 11 in.
| Year | Flood losses |
|---|---|
| 2016 | 164 |
| 2017 | 160 |
| 2018 | 70 |
| 2019 | 179 |
| 2020 | 232 |
| 2021 | 3,566 |
| 2022 | 56 |
| 2023 | 20 |
| 2024 | 1,193 |
| 2025 | 27 |
| 2026 to date | 185 |
Rain
| Average year, 1991-2020 | 63.49 in |
| 12 months to August 2026 | 52.60 in (-10.89) |
| 2025 | 54.78 in (-8.71) |
| Wettest year since 1895 | 1991: 102.08 in |
| Driest year since 1895 | 1917: 38.54 in |
| Days with 1 inch or more, normal at GALLIANO (16 mi away) | 22 |
Homes
| Housing units | 194,418 |
| Median year built | 1975 |
| Built before 1980 | 62% |
| Built 2000 or later | 14% |
| Owner-occupied | 63% |
| Median value, owner-occupied | $251,400 |
| Single-family detached | 65% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Lafourche Parish, LA | 20 mi | 42% | 74% |
| St. Charles Parish, LA | 30 mi | 44% | 63% |
| Plaquemines Parish, LA | 35 mi | 20% | 39% |
| Orleans Parish, LA | 36 mi | 29% | 37% |
| St. John the Baptist Parish, LA | 49 mi | 43% | 61% |
| Terrebonne Parish, LA | 49 mi | 34% | 65% |
| St. Bernard Parish, LA | 54 mi | 30% | 47% |
| St. James Parish, LA | 55 mi | 68% | 92% |
Sources: USDA SSURGO (September 5, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status