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St. Lawrence County, New York
A shallow water table limits basements on 49% of St. Lawrence County's mapped land, a higher share than 65% 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 19 flood losses here since 2016. 67% of homes were built before 1980, against 50% nationally; the median home dates from 1964.
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 St. Lawrence County
| Expansive clay (limits slab homes) | 11.1% |
| High water table (limits basements) | 48.8% |
| Septic fields very limited | 78.6% |
| Clay swell (LEP, by area) | 2.4% |
| High-swell land (LEP 6%+) | 11.1% |
| Mapped soil | 1,805,400 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Tunbridge | 7% | n/a |
| Muskellunge | 6% | n/a |
| Potsdam | 5% | n/a |
| Adams | 5% | n/a |
| Adjidaumo | 4% | n/a |
| Malone | 4% | n/a |
How we count · survey areas NY089 (2026-03-09)
What the numbers mean here
On 49% of St. Lawrence 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: 40.98 in, 0.13 in below the 1991-2020 average year of 41.11 in.
USDA rates 79% 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 13 of the last 52 weeks; the most was 100% of its area, in 3 weeks, most recently on the November 11, 2025 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 11.2% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
19 flood losses since 2016, $1.2 million paid. The worst year was 2024, with 8.
| Year | Flood losses |
|---|---|
| 2016 | 1 |
| 2017 | 6 |
| 2018 | 2 |
| 2019 | 2 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 8 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 41.11 in |
| 12 months to August 2026 | 40.98 in (-0.13) |
| 2025 | 36.02 in (-5.09) |
| Wettest year since 1895 | 1954: 50.56 in |
| Driest year since 1895 | 1941: 29.45 in |
| Days with 1 inch or more, normal at COLTON 2 N (9 mi away) | 6 |
Homes
| Housing units | 51,970 |
| Median year built | 1964 |
| Built before 1980 | 67% |
| Built 2000 or later | 14% |
| Owner-occupied | 72% |
| Median value, owner-occupied | $121,900 |
| Single-family detached | 72% |
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 |
|---|---|---|---|
| Franklin County, NY | 38 mi | 1% | 52% |
| Lewis County, NY | 52 mi | under 1% | 50% |
| Jefferson County, NY | 59 mi | 15% | 47% |
| Hamilton County, NY | 64 mi | 0% | 41% |
| Herkimer County, NY | 64 mi | under 1% | 45% |
| Essex County, NY | 69 mi | 3% | 31% |
| Clinton County, NY | 70 mi | 3% | 51% |
| Oneida County, NY | 88 mi | under 1% | 53% |
Sources: USDA SSURGO (March 9, 2026) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status