BasementSoil

Oregon: basement moisture and foundation risk by county

36 counties, ranked by our combined index. Highest combined risk is Coos County (53), lowest is Sherman County (20). The worst soil for foundation cracks specifically is in Clatsop County.

Where in Oregon the ground is worse

Every county in the state, coloured by the soil values below. Click a county to open its report; switch what the colour means with the buttons. The pattern is geology, not administration — risk stops at the edge of a physiographic region, not at a county line.

Baker County, OR — combined 30/100, moisture 30, movement 30, water table 30Benton County, OR — combined 46/100, moisture 45, movement 34, water table 66Clackamas County, OR — combined 49/100, moisture 46, movement 40, water table 66Clatsop County, OR — combined 49/100, moisture 34, movement 83, water table 30Columbia County, OR — combined 43/100, moisture 44, movement 25, water table 66Coos County, OR — combined 53/100, moisture 37, movement 79, water table 46Crook County, OR — combined 34/100, moisture 30, movement 43, water table 30Curry County, OR — combined 48/100, moisture 37, movement 75, water table 30Deschutes County, OR — combined 28/100, moisture 30, movement 23, water table 30Douglas County, OR — combined 49/100, moisture 35, movement 82, water table 30Gilliam County, OR — combined 34/100, moisture 32, movement 39, water table 30Grant County, OR — combined 34/100, moisture 30, movement 44, water table 30Harney County, OR — combined 36/100, moisture 32, movement 45, water table 30Hood River County, OR — combined 43/100, moisture 44, movement 24, water table 66Jackson County, OR — combined 28/100, moisture 28, movement 26, water table 30Jefferson County, OR — combined 24/100, moisture 29, movement 14, water table 30Josephine County, OR — combined 45/100, moisture 34, movement 71, water table 30Klamath County, OR — combined 27/100, moisture 26, movement 26, water table 30Lake County, OR — combined 26/100, moisture 28, movement 20, water table 30Lane County, OR — combined 42/100, moisture 48, movement 31, water table 46Lincoln County, OR — combined 49/100, moisture 34, movement 71, water table 46Linn County, OR — combined 41/100, moisture 44, movement 20, water table 66Malheur County, OR — combined 29/100, moisture 35, movement 20, water table 30Marion County, OR — combined 46/100, moisture 46, movement 32, water table 66Morrow County, OR — combined 31/100, moisture 34, movement 29, water table 30Multnomah County, OR — combined 41/100, moisture 45, movement 17, water table 66Polk County, OR — combined 38/100, moisture 47, movement 20, water table 46Sherman County, OR — combined 20/100, moisture 28, movement 13, water table 16Tillamook County, OR — combined 39/100, moisture 37, movement 59, water table 16Umatilla County, OR — combined 28/100, moisture 30, movement 24, water table 30Union County, OR — combined 33/100, moisture 30, movement 39, water table 30Wallowa County, OR — combined 27/100, moisture 31, movement 19, water table 30Wasco County, OR — combined 24/100, moisture 27, movement 16, water table 30Washington County, OR — combined 43/100, moisture 45, movement 25, water table 66Wheeler County, OR — combined 30/100, moisture 30, movement 29, water table 30Yamhill County, OR — combined 48/100, moisture 46, movement 39, water table 66
  • Low (0–27)
  • Moderate (28–49)
  • Elevated (50–74)
  • High (75–100)

County boundaries: US Census TIGER (public domain), simplified for display. Colours are our index from USDA SSURGO fields where loaded, otherwise from our regional model — each county page states which. How the index is calculated.

CountyIndexMoistureCracksWater tableRegion
Coos County53377946Pacific Coast Ranges
Clackamas County49464066Puget Sound and Willamette Lowland
Clatsop County49348330Pacific Coast Ranges
Douglas County49358230Pacific Coast Ranges
Lincoln County49347146Pacific Coast Ranges
Curry County48377530Pacific Coast Ranges
Yamhill County48463966Puget Sound and Willamette Lowland
Benton County46453466Puget Sound and Willamette Lowland
Marion County46463266Puget Sound and Willamette Lowland
Josephine County45347130Pacific Coast Ranges
Columbia County43442566Puget Sound and Willamette Lowland
Hood River County43442466Puget Sound and Willamette Lowland
Washington County43452566Puget Sound and Willamette Lowland
Lane County42483146Puget Sound and Willamette Lowland
Linn County41442066Puget Sound and Willamette Lowland
Multnomah County41451766Puget Sound and Willamette Lowland
Tillamook County39375916Pacific Coast Ranges
Polk County38472046Puget Sound and Willamette Lowland
Harney County36324530Columbia Plateau and Palouse
Crook County34304330Columbia Plateau and Palouse
Gilliam County34323930Columbia Plateau and Palouse
Grant County34304430Columbia Plateau and Palouse
Union County33303930Columbia Plateau and Palouse
Morrow County31342930Columbia Plateau and Palouse
Baker County30303030Columbia Plateau and Palouse
Wheeler County30302930Columbia Plateau and Palouse
Malheur County29352030Columbia Plateau and Palouse
Deschutes County28302330Sierra Nevada and Cascades
Jackson County28282630Sierra Nevada and Cascades
Umatilla County28302430Columbia Plateau and Palouse
Klamath County27262630Sierra Nevada and Cascades
Wallowa County27311930Columbia Plateau and Palouse
Lake County26282030Sierra Nevada and Cascades
Jefferson County24291430Sierra Nevada and Cascades
Wasco County24271630Sierra Nevada and Cascades
Sherman County20281316Sierra Nevada and Cascades

Values from USDA NRCS SSURGO where available, otherwise our regional model — each county page states which. Methodology.

The physiographic regions inside Oregon

State lines are political; soil follows geology. These are the distinct ground types inside Oregon and why each behaves the way it does.

Columbia Plateau and Palouse

Deep permeable loess on rolling hills, with basalt below. Water table deep, shrink-swell low. Loess is erodible and can settle under load when saturated, so a broken downspout does more damage here than the climate does.

11 counties: Baker County, Crook County, Gilliam County, Grant County, Harney County, Malheur County, Morrow County, Umatilla County, Union County, Wallowa County, Wheeler County

Puget Sound and Willamette Lowland

The one part of the West where basements are genuinely common — and the reason they leak is glacial: dense Vashon till under a permeable cap perches water just above it through the wet season. Volume change is low. Drainage, and hillside seepage, decide everything.

11 counties: Benton County, Clackamas County, Columbia County, Hood River County, Lane County, Linn County, Marion County, Multnomah County, Polk County, Washington County, Yamhill County

Pacific Coast Ranges

Some of the most expansive soils in North America sit here, on some of the least stable slopes. Winter rain saturates clay-rich colluvium and it moves — which is why hillside foundation work on the California and Oregon coast is engineered rather than standardised.

7 counties: Clatsop County, Coos County, Curry County, Douglas County, Josephine County, Lincoln County, Tillamook County

Sierra Nevada and Cascades

Coarse material over rock. Volume change is minimal and drainage is good; the seasonal problem is snowmelt arriving at foundations faster than it can be led away, not a water table.

7 counties: Deschutes County, Jackson County, Jefferson County, Klamath County, Lake County, Sherman County, Wasco County

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