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Clark County, South Dakota

A shallow water table limits basements on 65% of Clark County's mapped land, a higher share than 78% of US counties and the 5th highest of 66 South Dakota counties. Shrink-swell clay limits houses without basements on 19%.

12.2% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 1 flood losses here since 2016. 73% of homes were built before 1980, against 50% nationally; the median home dates from 1957.

Data as of October 13, 2026 · sources

19%

expansive clay: shrink-swell limits slab homes

65%

high water table: limits basements

12%

in drought, October 13, 2026

73%

of homes built before 1980

Soil under Clark County

Expansive clay (limits slab homes)19.1%
High water table (limits basements)65.1%
Septic fields very limited92.6%
Clay swell (LEP, by area)4.4%
High-swell land (LEP 6%+)19.1%
Mapped soil619,578 acres
Soil seriesShare hereSeries nationally: high water table
Barnes13%20%
Buse11%n/a
Poinsett9%n/a
Svea6%n/a
Southam5%n/a
Waubay5%n/a
Codington County: 65%Hamlin County: 67%Spink County: 56%Day County: 63%Kingsbury County: 50%Beadle County: 30%Deuel County: 71%Grant County: 56%Clark County CodingtonHamlinSpinkDayKingsburyBeadleDeuelGrantClark
Clark 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 SD025 (2025-09-10)

What the numbers mean here

Clay swell averages a linear extensibility of 4.4% by land area here, and 19% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 19% of the mapped land.

Clay shrinks as it dries: 12.2% of the county is in drought on the latest map, and 19% of Clark County's mapped land has shrink-swell clay.

On 65% of Clark 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: 19.75 in, 4.31 in below the 1991-2020 average year of 24.06 in.

USDA rates 93% of the land very limited for septic absorption fields.

Drought

12.2% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 22 of the last 52 weeks; the most was 18.7% of its area, in 3 weeks, most recently on the June 2, 2026 map.

October 21, 2025Share of area in drought, weeklyOctober 13, 2026
Category, October 13, 2026Share of county
D0 abnormally dry or worse74.9%
D1 moderate drought or worse12.2%
D2 severe or worse0%
D3 extreme or worse0%
D4 exceptional0%

Flood losses since 2016

1 flood losses since 2016, $5,069 paid. The worst year was 2019, with 1.

YearFlood losses
20160
20170
20180
20191
20200
20210
20220
20230
20240
20250
2026 to date0

Rain

Average year, 1991-202024.06 in
12 months to August 202619.75 in (-4.31)
202527.96 in (+3.90)
Wettest year since 18952019: 36.78 in
Driest year since 18951976: 10.21 in
Days with 1 inch or more, normal at BRYANT (24 mi away)6.2

Homes

Housing units1,609
Median year built1957
Built before 198073%
Built 2000 or later14%
Owner-occupied78%
Median value, owner-occupied$158,400
Single-family detached84%

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
Codington County, SD 27 mi 11% 65%
Hamlin County, SD 29 mi 13% 67%
Spink County, SD 30 mi 45% 56%
Day County, SD 35 mi 19% 63%
Kingsbury County, SD 36 mi 30% 50%
Beadle County, SD 41 mi 37% 30%
Deuel County, SD 51 mi 13% 71%
Grant County, SD 51 mi 26% 56%

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