Seneca County, New York
A shallow water table limits basements on 57% of Seneca County's mapped land, a higher share than 72% of US counties. Shrink-swell clay limits houses without basements on 11%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 28 flood losses here since 2016. 69% of homes were built before 1980, against 50% nationally; the median home dates from 1959.
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 Seneca County
| Expansive clay (limits slab homes) | 10.7% |
| High water table (limits basements) | 57.1% |
| Septic fields very limited | 62.2% |
| Clay swell (LEP, by area) | 3.4% |
| High-swell land (LEP 6%+) | 10.7% |
| Mapped soil | 261,363 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Darien | 6% | n/a |
| Cazenovia | 6% | n/a |
| Schoharie | 5% | n/a |
| Lima | 5% | n/a |
| Honeoye | 4% | n/a |
| Odessa | 4% | n/a |
How we count · survey areas NY099 (2025-09-02)
What the numbers mean here
On 57% of Seneca County'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: 35.65 in, 0.95 in below the 1991-2020 average year of 36.60 in.
USDA rates 62% of the land very limited for septic absorption fields.
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 21 of the last 52 weeks; the most was 80.4% of its area, on the October 21, 2025 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 95.9% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
28 flood losses since 2016, $545,983 paid. The worst year was 2018, with 12.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 4 |
| 2018 | 12 |
| 2019 | 0 |
| 2020 | 2 |
| 2021 | 6 |
| 2022 | 1 |
| 2023 | 2 |
| 2024 | 1 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 36.60 in |
| 12 months to August 2026 | 35.65 in (-0.95) |
| 2025 | 31.48 in (-5.12) |
| Wettest year since 1895 | 1972: 45.68 in |
| Driest year since 1895 | 1965: 25.15 in |
| Days with 1 inch or more, normal at AURORA RSCH FARM (9 mi away) | 5.6 |
Homes
| Housing units | 16,194 |
| Median year built | 1959 |
| Built before 1980 | 69% |
| Built 2000 or later | 13% |
| Owner-occupied | 71% |
| Median value, owner-occupied | $155,400 |
| Single-family detached | 70% |
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 |
|---|---|---|---|
| Yates County, NY | 17 mi | 1% | 83% |
| Cayuga County, NY | 20 mi | 3% | 56% |
| Ontario County, NY | 25 mi | 11% | 59% |
| Schuyler County, NY | 26 mi | 2% | 62% |
| Tompkins County, NY | 29 mi | under 1% | 70% |
| Wayne County, NY | 32 mi | 1% | 56% |
| Onondaga County, NY | 35 mi | 1% | 46% |
| Cortland County, NY | 40 mi | 0% | 62% |
Sources: USDA SSURGO (September 2, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status