Calvert County, Maryland
A shallow water table limits basements on 56% of Calvert County's mapped land, a higher share than 71% of US counties and the 8th highest of 24 Maryland counties. Shrink-swell clay limits houses without basements on under 1%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 73 flood losses here since 2016, 4% of them in buildings with basements. 32% of homes were built before 1980, against 50% nationally; the median home dates from 1990.
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 Calvert County
| Expansive clay (limits slab homes) | 0.1% |
| High water table (limits basements) | 55.7% |
| Septic fields very limited | 87.8% |
| Clay swell (LEP, by area) | 1.7% |
| High-swell land (LEP 6%+) | under 0.1% |
| Mapped soil | 153,800 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Dodon | 21% | n/a |
| Downer | 15% | n/a |
| Marr | 11% | n/a |
| Ingleside | 9% | n/a |
| Woodstown | 7% | n/a |
| Issue | 6% | n/a |
How we count · survey areas MD009 (2025-09-09)
What the numbers mean here
On 56% of Calvert 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: 33.10 in, 12.63 in below the 1991-2020 average year of 45.73 in.
USDA rates 88% 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 34 of the last 52 weeks; the most was 100% of its area, in 24 weeks, most recently on the July 28, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 80.2% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
73 flood losses since 2016, $912,234 paid. The worst year was 2021, with 33. Foundations of the buildings, where recorded: 4% basements, 18% slabs, 39% crawl spaces, 39% elevated. Median water depth outside the building: 12 in.
| Year | Flood losses |
|---|---|
| 2016 | 3 |
| 2017 | 1 |
| 2018 | 8 |
| 2019 | 5 |
| 2020 | 14 |
| 2021 | 33 |
| 2022 | 2 |
| 2023 | 2 |
| 2024 | 4 |
| 2025 | 1 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 45.73 in |
| 12 months to August 2026 | 33.10 in (-12.63) |
| 2025 | 39.46 in (-6.27) |
| Wettest year since 1895 | 2018: 69.06 in |
| Driest year since 1895 | 1930: 23.22 in |
| Days with 1 inch or more, normal at MECHANICSVILLE 5 NE (11 mi away) | 12.4 |
Homes
| Housing units | 36,119 |
| Median year built | 1990 |
| Built before 1980 | 32% |
| Built 2000 or later | 28% |
| Owner-occupied | 87% |
| Median value, owner-occupied | $460,200 |
| Single-family detached | 88% |
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 |
|---|---|---|---|
| St. Mary's County, MD | 20 mi | 1% | 47% |
| Talbot County, MD | 25 mi | 0% | 65% |
| Charles County, MD | 26 mi | 4% | 61% |
| Dorchester County, MD | 27 mi | 0% | 69% |
| Prince George's County, MD | 28 mi | 1% | 46% |
| Westmoreland County, VA | 32 mi | 8% | 38% |
| Anne Arundel County, MD | 33 mi | 0% | 46% |
| Alexandria city, VA | 37 mi | 3% | 44% |
Sources: USDA SSURGO (September 9, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status