Kauai County, Hawaii
USDA's soil survey flags shrink-swell clay on 5% of Kauai County's mapped land and a shallow water table under basements on 8%, both below the national shares of 15% and 29%. None of the county is in drought on the November 3, 2026 Drought Monitor map.
FEMA's flood data list 351 flood losses here since 2016, 2% of them in buildings with basements. 43% of homes were built before 1980, against 50% nationally; the median home dates from 1983.
Data as of November 3, 2026 · sources
expansive clay: shrink-swell limits slab homes
high water table: limits basements
in drought, November 3, 2026
of homes built before 1980
Soil under Kauai County
| Expansive clay (limits slab homes) | 5.3% |
| High water table (limits basements) | 7.8% |
| Septic fields very limited | 90.6% |
| Clay swell (LEP, by area) | 2.0% |
| High-swell land (LEP 6%+) | 4.5% |
| Mapped soil | 357,200 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Lihue | 4% | n/a |
| Puhi | 4% | n/a |
| Makaweli | 4% | n/a |
| Kapaa | 3% | n/a |
| Hihimanu | 2% | n/a |
| Mahana | 2% | n/a |
How we count · survey areas HI960 (2025-09-09)
What the numbers mean here
Rain over the 12 months to August 2026: 95.51 in, 20.06 in above the 1991-2020 average year of 75.45 in.
USDA rates 91% of the land very limited for septic absorption fields.
With shrink-swell clay on 5% and a shallow water table on 8% of the land, the soil survey points to neither problem across most of Kauai County; conditions still vary lot by lot.
Drought
0% of the county is in drought (D1 or worse) on the November 3, 2026 map. Part of the county was in drought in 5 of the last 52 weeks; the most was 82.8% of its area, in 2 weeks, most recently on the December 9, 2025 map.
| Category, November 3, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 0% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
351 flood losses since 2016, $12.3 million paid. The worst year was 2018, with 206. Foundations of the buildings, where recorded: 2% basements, 36% slabs, 3% crawl spaces, 59% elevated. Median water depth outside the building: 23 in.
| Year | Flood losses |
|---|---|
| 2016 | 1 |
| 2017 | 3 |
| 2018 | 206 |
| 2019 | 13 |
| 2020 | 38 |
| 2021 | 11 |
| 2022 | 2 |
| 2023 | 1 |
| 2024 | 67 |
| 2025 | 4 |
| 2026 to date | 5 |
Rain
| Average year, 1991-2020 | 75.45 in |
| 12 months to August 2026 | 95.51 in (+20.06) |
| 2025 | 67.01 in (-8.44) |
| Wettest year since 1991 | 2018: 121.60 in |
| Driest year since 1991 | 2022: 48.01 in |
| Days with 1 inch or more, normal at PRINCEVILLE RCH 1117 (20 mi away) | 12.8 |
Homes
| Housing units | 30,471 |
| Median year built | 1983 |
| Built before 1980 | 43% |
| Built 2000 or later | 20% |
| Owner-occupied | 69% |
| Median value, owner-occupied | $873,200 |
| Single-family detached | 69% |
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 |
|---|---|---|---|
| Honolulu County, HI | 104 mi | 12% | 4% |
| Kalawao County, HI | 184 mi | n/a | n/a |
| Maui County, HI | 215 mi | 4% | 5% |
| Hawaii County, HI | 319 mi | 4% | 4% |
| Aleutians East Borough, AK | 2299 mi | 0% | 11% |
| Aleutians West Census Area, AK | 2344 mi | n/a | n/a |
| San Francisco County, CA | 2430 mi | 0% | 3% |
| Mendocino County, CA | 2445 mi | 9% | 6% |
Sources: USDA SSURGO (September 9, 2025) · US Drought Monitor (November 3, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status