HomeSouth DakotaCuster County

Custer County, South Dakota

Shrink-swell clay limits houses without basements on 17% of Custer County's mapped land, a higher share than 66% of US counties. A shallow water table limits basements on 1%.

100% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 9 flood losses here since 2016. 39% of homes were built before 1980, against 50% nationally; the median home dates from 1994.

Data as of October 13, 2026 · sources

17%

expansive clay: shrink-swell limits slab homes

1%

high water table: limits basements

100%

in drought, October 13, 2026

39%

of homes built before 1980

Soil under Custer County

Expansive clay (limits slab homes)17.3%
High water table (limits basements)1.1%
Septic fields very limited70.2%
Clay swell (LEP, by area)3.9%
High-swell land (LEP 6%+)23.5%
Mapped soil896,991 acres
Soil seriesShare hereSeries nationally: expansive clay
Sawdust8%n/a
Satanta7%n/a
Rockerville7%n/a
Vanocker6%n/a
Midway4%n/a
Fairburn3%n/a
Fall River County: 55%Pennington County: 52%Lawrence County: 22%Oglala Lakota County: 23%Weston County: 27%Niobrara County: 10%Dawes County: 24%Meade County: 49%Custer County Fall RiverPenningtonLawrenceOglala LakotaWestonNiobraraDawesMeadeCuster
Custer County (heavy outline) and nearby counties, shaded by expansive clay share.under 10%10-25%25-40%40-60%60%+

How we count · survey areas SD606 (2025-09-10), SD607 (2025-09-10)

What the numbers mean here

Clay swell averages a linear extensibility of 3.9% by land area here, and 24% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 17% of the mapped land.

Clay shrinks as it dries: 100% of the county is in drought on the latest map, and 17% of Custer County's mapped land has shrink-swell clay.

Rain over the 12 months to August 2026: 14.27 in, 4.98 in below the 1991-2020 average year of 19.25 in.

USDA rates 70% 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 38 of the last 52 weeks; the most was 100% of its area, in 35 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 worse0%
D3 extreme or worse0%
D4 exceptional0%

Flood losses since 2016

9 flood losses since 2016, $84,878 paid. The worst year was 2019, with 8.

YearFlood losses
20160
20170
20181
20198
20200
20210
20220
20230
20240
20250
2026 to date0

Rain

Average year, 1991-202019.25 in
12 months to August 202614.27 in (-4.98)
202516.79 in (-2.46)
Wettest year since 18951915: 29.68 in
Driest year since 18951960: 10.50 in
Days with 1 inch or more, normal at WIND CAVE (9 mi away)3

Homes

Housing units5,291
Median year built1994
Built before 198039%
Built 2000 or later43%
Owner-occupied86%
Median value, owner-occupied$372,100
Single-family detached75%

What repairs cost

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

WorkRangeSource
Foundation repair, US $2,200 to $8,200 Fixr, January 27, 2026
Pier-and-beam repair, US $2,000 to $15,000 Fixr, January 27, 2026
Foundation inspection, US $300 to $600 Fixr, January 31, 2025

Nearby counties

PlaceDistanceExpansive clayHigh water table
Fall River County, SD 32 mi 55% 1%
Pennington County, SD 38 mi 52% 1%
Lawrence County, SD 49 mi 22% 1%
Oglala Lakota County, SD 50 mi 23% 1%
Weston County, WY 58 mi 27% 1%
Niobrara County, WY 67 mi 10% 1%
Dawes County, NE 69 mi 24% 1%
Meade County, SD 73 mi 49% 1%

Sources: USDA SSURGO (September 10, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status