Terrebonne Parish, Louisiana

A shallow water table limits basements on 65% of Terrebonne Parish's mapped land, a higher share than 78% of US counties. Shrink-swell clay limits houses without basements on 34%.

5.6% of the county is in drought on the October 13, 2026 Drought Monitor map, up from 0% a week earlier. FEMA's flood data list 846 flood losses here since 2016, 0% of them in buildings with basements. 47% of homes were built before 1980, against 50% nationally; the median home dates from 1983.

Data as of October 13, 2026 · sources

34%

expansive clay: shrink-swell limits slab homes

65%

high water table: limits basements

in drought, October 13, 2026

47%

of homes built before 1980

Soil under Terrebonne Parish

Expansive clay (limits slab homes)	33.9%
High water table (limits basements)	65.4%
Septic fields very limited	62.7%
Clay swell (LEP, by area)	11.8%
High-swell land (LEP 6%+)	35.2%
Mapped soil	1,034,100 acres

Soil series	Share here	Series nationally: high water table
Kenner	10%	n/a
Allemands	8%	n/a
Clovelly	8%	n/a
Lafitte	6%	n/a
Schriever	6%	n/a
Timbalier	6%	n/a

Terrebonne Parish (heavy outline) and nearby counties, shaded by high water table share.under 10%10-25%25-40%40-60%60%+

How we count · survey areas LA109 (2025-08-29)

What the numbers mean here

Clay swell averages a linear extensibility of 11.8% by land area here, and 35% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 34% of the mapped land.

Clay shrinks as it dries: 5.6% of the county is in drought on the latest map, and 34% of Terrebonne Parish's mapped land has shrink-swell clay.

On 65% of Terrebonne 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: 46.62 in, 14.79 in below the 1991-2020 average year of 61.41 in.

USDA rates 63% of the land very limited for septic absorption fields.

Drought

5.6% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 31 of the last 52 weeks; the most was 100% of its area, in 17 weeks, most recently on the May 26, 2026 map.

October 21, 2025Share of area in drought, weeklyOctober 13, 2026

Category, October 13, 2026	Share of county
D0 abnormally dry or worse	100%
D1 moderate drought or worse	5.6%
D2 severe or worse	0%
D3 extreme or worse	0%
D4 exceptional	0%

Flood losses since 2016

846 flood losses since 2016, $15.2 million paid. The worst year was 2021, with 467. Foundations of the buildings, where recorded: 75% slabs, 3% crawl spaces, 22% elevated. Median water depth outside the building: 10 in.

Year	Flood losses
2016	13
2017	31
2018	11
2019	85
2020	68
2021	467
2022	8
2023	4
2024	53
2025	7
2026 to date	99

Rain

Average year, 1991-2020	61.41 in
12 months to August 2026	46.62 in (-14.79)
2025	47.26 in (-14.15)
Wettest year since 1895	1991: 91.74 in
Driest year since 1895	2023: 35.69 in
Days with 1 inch or more, normal at THIBODAUX 4 SE (29 mi away)	22.2

Homes

Housing units	47,392
Median year built	1983
Built before 1980	47%
Built 2000 or later	28%
Owner-occupied	75%
Median value, owner-occupied	$187,200
Single-family detached	71%

What repairs cost

Published ranges from cost guides, not quotes. More sources, and where they disagree.

Work	Range	Source
Basement waterproofing, US	$3,000 to $10,000	Fixr, February 6, 2026
Sump pump installation, US	$800 to $2,000	Fixr, January 31, 2025
Crawl space encapsulation, US	$2,000 to $8,000	Fixr, August 29, 2025

Nearby counties

Place	Distance	Expansive clay	High water table
Lafourche Parish, LA	29 mi	42%	74%
Assumption Parish, LA	42 mi	68%	88%
St. Mary Parish, LA	43 mi	52%	80%
St. James Parish, LA	48 mi	68%	92%
St. Charles Parish, LA	49 mi	44%	63%
Jefferson Parish, LA	49 mi	27%	44%
St. John the Baptist Parish, LA	60 mi	43%	61%
Ascension Parish, LA	60 mi	46%	91%

Sources: USDA SSURGO (August 29, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status