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Placer County, California
USDA's soil survey flags shrink-swell clay on 7% of Placer County's mapped land and a shallow water table under basements on 4%, both below the national shares of 15% and 29%. The soil survey maps 68% of the county's land area; these shares describe the mapped part.
10.9% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 33 flood losses here since 2016, 10% of them in buildings with basements. 28% of homes were built before 1980, against 50% nationally; the median home dates from 1994.
Data as of October 13, 2026 · sources
expansive clay: shrink-swell limits slab homes
high water table: limits basements
in drought, October 13, 2026
of homes built before 1980
Soil under Placer County
| Expansive clay (limits slab homes) | 6.9% |
| High water table (limits basements) | 4.4% |
| Septic fields very limited | 73.5% |
| Clay swell (LEP, by area) | 3.1% |
| High-swell land (LEP 6%+) | 10.6% |
| Mapped soil | 608,585 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Mariposa | 6% | n/a |
| Auburn | 6% | n/a |
| Andregg | 5% | n/a |
| McCarthy | 4% | n/a |
| Cometa | 4% | n/a |
| Fiddyment | 3% | n/a |
How we count · survey areas CA620 (2025-09-02), CA693 (2025-09-02), CA724 (2025-09-02)
What the numbers mean here
Rain over the 12 months to August 2026: 47.04 in, 0.36 in above the 1991-2020 average year of 46.68 in.
USDA rates 74% of the land very limited for septic absorption fields.
With shrink-swell clay on 7% and a shallow water table on 4% of the land, the soil survey points to neither problem across most of Placer County; conditions still vary lot by lot.
Drought
10.9% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 13 of the last 52 weeks; the most was 55.8% of its area, on the April 7, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 10.9% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
33 flood losses since 2016, $693,404 paid. The worst year was 2017, with 8. Foundations of the buildings, where recorded: 10% basements, 67% slabs, 19% crawl spaces, 5% elevated.
| Year | Flood losses |
|---|---|
| 2016 | 1 |
| 2017 | 8 |
| 2018 | 5 |
| 2019 | 1 |
| 2020 | 1 |
| 2021 | 3 |
| 2022 | 3 |
| 2023 | 7 |
| 2024 | 2 |
| 2025 | 1 |
| 2026 to date | 1 |
Rain
| Average year, 1991-2020 | 46.68 in |
| 12 months to August 2026 | 47.04 in (+0.36) |
| 2025 | 48.64 in (+1.96) |
| Wettest year since 1895 | 1983: 85.71 in |
| Driest year since 1895 | 2013: 14.60 in |
| Days with 1 inch or more, normal at FORESTHILL RS (8 mi away) | 17.8 |
Homes
| Housing units | 179,266 |
| Median year built | 1994 |
| Built before 1980 | 28% |
| Built 2000 or later | 39% |
| Owner-occupied | 75% |
| Median value, owner-occupied | $688,100 |
| Single-family detached | 78% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Nevada County, CA | 17 mi | 2% | 1% |
| El Dorado County, CA | 22 mi | 1% | 2% |
| Yuba County, CA | 36 mi | 21% | 5% |
| Sierra County, CA | 37 mi | 5% | 9% |
| Amador County, CA | 43 mi | 1% | 3% |
| Carson City, NV | 52 mi | 11% | 5% |
| Sutter County, CA | 53 mi | 41% | 37% |
| Sacramento County, CA | 54 mi | 16% | 26% |
Sources: USDA SSURGO (September 2, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status