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San Juan County, New Mexico

USDA's soil survey flags shrink-swell clay on 5% of San Juan County's mapped land and a shallow water table under basements on 2%, both below the national shares of 15% and 29%. 92.7% of the county is in drought on the October 13, 2026 Drought Monitor map.

FEMA's flood data list 3 flood losses here since 2016. 39% of homes were built before 1980, against 50% nationally; the median home dates from 1986.

Data as of October 13, 2026 · sources

5%

expansive clay: shrink-swell limits slab homes

2%

high water table: limits basements

93%

in drought, October 13, 2026

39%

of homes built before 1980

Soil under San Juan County

Expansive clay (limits slab homes)5.5%
High water table (limits basements)2.3%
Septic fields very limited77.8%
Clay swell (LEP, by area)3.2%
High-swell land (LEP 6%+)6.0%
Mapped soil3,619,895 acres
Soil seriesShare hereSeries nationally: expansive clay
Sheppard6%n/a
Persayo5%n/a
Shiprock4%n/a
Notal4%n/a
Blancot4%n/a
Doak3%n/a
Montezuma County: 13%La Plata County: 10%McKinley County: 22%Dolores County: 12%Archuleta County: 53%Rio Arriba County: 14%San Juan County: 0%Sandoval County: 7%San Juan County MontezumaLa PlataMcKinleyDoloresArchuletaRio ArribaSan JuanSandovalSan Juan
San Juan 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 AZ713 (2025-08-27), AZ715 (2025-08-27), CO670 (2025-08-29), NM618 (2025-09-09), NM692 (2025-09-09), NM717 (2025-09-09)

What the numbers mean here

Rain over the 12 months to August 2026: 7.32 in, 1.62 in below the 1991-2020 average year of 8.94 in.

USDA rates 78% of the land very limited for septic absorption fields.

With shrink-swell clay on 5% and a shallow water table on 2% of the land, the soil survey points to neither problem across most of San Juan County; conditions still vary lot by lot.

Drought

92.7% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 52 of the last 52 weeks; the most was 100% of its area, in 35 weeks, most recently on the September 29, 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 worse92.7%
D2 severe or worse75.1%
D3 extreme or worse0%
D4 exceptional0%

Flood losses since 2016

3 flood losses since 2016, $34,857 paid. The worst year was 2017, with 2.

YearFlood losses
20160
20172
20180
20190
20200
20210
20220
20230
20241
20250
2026 to date0

Rain

Average year, 1991-20208.94 in
12 months to August 20267.32 in (-1.62)
20257.07 in (-1.87)
Wettest year since 18951941: 19.29 in
Driest year since 18951950: 4.33 in
Days with 1 inch or more, normal at FARMINGTON AG SCI CNT (10 mi away)0.2

Homes

Housing units48,255
Median year built1986
Built before 198039%
Built 2000 or later24%
Owner-occupied71%
Median value, owner-occupied$193,800
Single-family detached57%

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
Montezuma County, CO 57 mi 13% 2%
La Plata County, CO 58 mi 10% 3%
McKinley County, NM 66 mi 22% under 1%
Dolores County, CO 83 mi 12% 2%
Archuleta County, CO 85 mi 53% 3%
Rio Arriba County, NM 92 mi 14% 3%
San Juan County, CO 93 mi 0% 1%
Sandoval County, NM 101 mi 7% 1%

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