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Hamlin County, South Dakota

A shallow water table limits basements on 67% of Hamlin County's mapped land, a higher share than 79% of US counties and the 3rd highest of 66 South Dakota counties. Shrink-swell clay limits houses without basements on 13%.

11.3% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 69 flood losses here since 2016. 62% of homes were built before 1980, against 50% nationally; the median home dates from 1969.

Data as of October 13, 2026 · sources

13%

expansive clay: shrink-swell limits slab homes

67%

high water table: limits basements

11%

in drought, October 13, 2026

62%

of homes built before 1980

Soil under Hamlin County

Expansive clay (limits slab homes)12.8%
High water table (limits basements)66.7%
Septic fields very limited94.5%
Clay swell (LEP, by area)4.4%
High-swell land (LEP 6%+)12.8%
Mapped soil341,404 acres
Soil seriesShare hereSeries nationally: high water table
Poinsett21%n/a
Buse11%n/a
Waubay10%n/a
Cubden5%n/a
Vienna5%n/a
Badger4%n/a
Codington County: 65%Deuel County: 71%Kingsbury County: 50%Brookings County: 67%Clark County: 65%Grant County: 56%Lake County: 27%Lincoln County: 83%Hamlin County CodingtonDeuelKingsburyBrookingsClarkGrantLakeLincolnHamlin
Hamlin 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 SD057 (2025-09-10)

What the numbers mean here

On 67% of Hamlin 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: 19.52 in, 5.79 in below the 1991-2020 average year of 25.31 in.

USDA rates 94% of the land very limited for septic absorption fields.

Drought

11.3% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 26 of the last 52 weeks; the most was 55.2% 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 worse87.4%
D1 moderate drought or worse11.3%
D2 severe or worse0%
D3 extreme or worse0%
D4 exceptional0%

Flood losses since 2016

69 flood losses since 2016, $910,648 paid. The worst year was 2019, with 68. Median water depth outside the building: 10 in.

YearFlood losses
20160
20170
20180
201968
20201
20210
20220
20230
20240
20250
2026 to date0

Rain

Average year, 1991-202025.31 in
12 months to August 202619.52 in (-5.79)
202530.65 in (+5.34)
Wettest year since 18952019: 38.04 in
Driest year since 18951976: 11.11 in
Days with 1 inch or more, normal at WATERTOWN RGNL AP (16 mi away)4.1

Homes

Housing units2,860
Median year built1969
Built before 198062%
Built 2000 or later25%
Owner-occupied82%
Median value, owner-occupied$208,600
Single-family detached88%

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 20 mi 11% 65%
Deuel County, SD 25 mi 13% 71%
Kingsbury County, SD 27 mi 30% 50%
Brookings County, SD 28 mi 10% 67%
Clark County, SD 29 mi 19% 65%
Grant County, SD 39 mi 26% 56%
Lake County, SD 45 mi 30% 27%
Lincoln County, MN 48 mi 13% 83%

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