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Knox County, Maine

A shallow water table limits basements on 42% of Knox County's mapped land, a higher share than 60% of US counties. Shrink-swell clay limits houses without basements on 0%.

100% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 42 flood losses here since 2016, 23% of them in buildings with basements. 57% of homes were built before 1980, against 50% nationally; the median home dates from 1974.

Data as of October 13, 2026 · sources

0%

expansive clay: shrink-swell limits slab homes

42%

high water table: limits basements

100%

in drought, October 13, 2026

57%

of homes built before 1980

Soil under Knox County

Expansive clay (limits slab homes)0.0%
High water table (limits basements)42.2%
Septic fields very limited72.9%
Clay swell (LEP, by area)1.2%
High-swell land (LEP 6%+)0.0%
Mapped soil302,566 acres
Soil seriesShare hereSeries nationally: high water table
Peru13%n/a
Lyman12%n/a
Swanville8%n/a
Tunbridge8%n/a
Boothbay7%n/a
Brayton5%n/a
Lincoln County: 43%Waldo County: 57%Sagadahoc County: 38%Kennebec County: 59%Hancock County: 47%Androscoggin County: 45%Cumberland County: 49%Oxford County: 48%Knox County LincolnWaldoSagadahocKennebecHancockAndroscogginCumberlandOxfordKnox
Knox County (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 ME601 (2025-08-29)

What the numbers mean here

On 42% of Knox 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: 36.15 in, 13.58 in below the 1991-2020 average year of 49.73 in.

USDA rates 73% of the land very limited for septic absorption fields.

Drought

100% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 48 of the last 52 weeks; the most was 100% of its area, in 42 weeks, most recently on the October 13, 2026 map.

October 21, 2025Share of area in drought, weeklyOctober 13, 2026
Category, October 13, 2026Share of county
D0 abnormally dry or worse100%
D1 moderate drought or worse100%
D2 severe or worse100%
D3 extreme or worse98.3%
D4 exceptional0%

Flood losses since 2016

42 flood losses since 2016, $1.6 million paid. The worst year was 2024, with 26. Foundations of the buildings, where recorded: 23% basements, 36% slabs, 15% crawl spaces, 26% elevated. Median water depth outside the building: 21 in.

YearFlood losses
20162
20170
20180
20192
20201
20212
20226
20232
202426
20251
2026 to date0

Rain

Average year, 1991-202049.73 in
12 months to August 202636.15 in (-13.58)
202542.99 in (-6.74)
Wettest year since 18952005: 70.07 in
Driest year since 18951941: 29.78 in
Days with 1 inch or more, normal at TENANTS HARBOR (10 mi away)12.4

Homes

Housing units24,564
Median year built1974
Built before 198057%
Built 2000 or later18%
Owner-occupied79%
Median value, owner-occupied$324,900
Single-family detached79%

What repairs cost

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

WorkRangeSource
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

PlaceDistanceExpansive clayHigh water table
Lincoln County, ME 24 mi 0% 43%
Waldo County, ME 30 mi 0% 57%
Sagadahoc County, ME 41 mi 0% 38%
Kennebec County, ME 44 mi 0% 59%
Hancock County, ME 49 mi 0% 47%
Androscoggin County, ME 59 mi 0% 45%
Cumberland County, ME 66 mi 0% 49%
Oxford County, ME 90 mi 0% 48%

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