BasementSoil

Idaho: basement moisture and foundation risk by county

44 counties, ranked by our combined index. Highest combined risk is Bonner County (35), lowest is Nez Perce County (22). The worst soil for foundation cracks specifically is in Clark County.

Where in Idaho 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.

Ada County, ID — combined 29/100, moisture 32, movement 35, water table 16Adams County, ID — combined 30/100, moisture 29, movement 20, water table 46Bannock County, ID — combined 30/100, moisture 34, movement 25, water table 30Bear Lake County, ID — combined 34/100, moisture 32, movement 39, water table 30Benewah County, ID — combined 34/100, moisture 30, movement 41, water table 30Bingham County, ID — combined 30/100, moisture 33, movement 27, water table 30Blaine County, ID — combined 27/100, moisture 30, movement 21, water table 30Boise County, ID — combined 24/100, moisture 33, movement 18, water table 16Bonner County, ID — combined 35/100, moisture 29, movement 34, water table 46Bonneville County, ID — combined 27/100, moisture 31, movement 28, water table 16Boundary County, ID — combined 32/100, moisture 28, movement 39, water table 30Butte County, ID — combined 27/100, moisture 33, movement 26, water table 16Camas County, ID — combined 30/100, moisture 33, movement 37, water table 16Canyon County, ID — combined 33/100, moisture 31, movement 38, water table 30Caribou County, ID — combined 31/100, moisture 30, movement 34, water table 30Cassia County, ID — combined 33/100, moisture 32, movement 36, water table 30Clark County, ID — combined 35/100, moisture 31, movement 43, water table 30Clearwater County, ID — combined 33/100, moisture 30, movement 39, water table 30Custer County, ID — combined 30/100, moisture 34, movement 25, water table 30Elmore County, ID — combined 30/100, moisture 31, movement 30, water table 30Franklin County, ID — combined 33/100, moisture 30, movement 38, water table 30Fremont County, ID — combined 33/100, moisture 34, movement 33, water table 30Gem County, ID — combined 32/100, moisture 32, movement 34, water table 30Gooding County, ID — combined 32/100, moisture 31, movement 35, water table 30Idaho County, ID — combined 29/100, moisture 29, movement 39, water table 16Jefferson County, ID — combined 30/100, moisture 31, movement 30, water table 30Jerome County, ID — combined 28/100, moisture 33, movement 20, water table 30Kootenai County, ID — combined 27/100, moisture 31, movement 20, water table 30Latah County, ID — combined 25/100, moisture 29, movement 25, water table 16Lemhi County, ID — combined 30/100, moisture 28, movement 34, water table 30Lewis County, ID — combined 28/100, moisture 28, movement 36, water table 16Lincoln County, ID — combined 29/100, moisture 31, movement 26, water table 30Madison County, ID — combined 27/100, moisture 32, movement 19, water table 30Minidoka County, ID — combined 30/100, moisture 30, movement 29, water table 30Nez Perce County, ID — combined 22/100, moisture 28, movement 18, water table 16Oneida County, ID — combined 34/100, moisture 34, movement 38, water table 30Owyhee County, ID — combined 30/100, moisture 30, movement 29, water table 30Payette County, ID — combined 32/100, moisture 32, movement 34, water table 30Power County, ID — combined 31/100, moisture 33, movement 28, water table 30Shoshone County, ID — combined 29/100, moisture 30, movement 27, water table 30Teton County, ID — combined 31/100, moisture 33, movement 28, water table 30Twin Falls County, ID — combined 28/100, moisture 30, movement 24, water table 30Valley County, ID — combined 29/100, moisture 28, movement 17, water table 46Washington County, ID — combined 34/100, moisture 33, movement 37, water table 30
  • 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
Bonner County35293446Rocky Mountains
Clark County35314330Snake River Plain
Bear Lake County34323930Snake River Plain
Benewah County34304130Rocky Mountains
Oneida County34343830Snake River Plain
Washington County34333730Snake River Plain
Canyon County33313830Snake River Plain
Cassia County33323630Snake River Plain
Clearwater County33303930Rocky Mountains
Franklin County33303830Snake River Plain
Fremont County33343330Snake River Plain
Boundary County32283930Rocky Mountains
Gem County32323430Snake River Plain
Gooding County32313530Snake River Plain
Payette County32323430Snake River Plain
Caribou County31303430Snake River Plain
Power County31332830Snake River Plain
Teton County31332830Snake River Plain
Adams County30292046Rocky Mountains
Bannock County30342530Snake River Plain
Bingham County30332730Snake River Plain
Camas County30333716Snake River Plain
Custer County30342530Snake River Plain
Elmore County30313030Snake River Plain
Jefferson County30313030Snake River Plain
Lemhi County30283430Rocky Mountains
Minidoka County30302930Snake River Plain
Owyhee County30302930Snake River Plain
Ada County29323516Snake River Plain
Idaho County29293916Rocky Mountains
Lincoln County29312630Snake River Plain
Shoshone County29302730Rocky Mountains
Valley County29281746Rocky Mountains
Jerome County28332030Snake River Plain
Lewis County28283616Rocky Mountains
Twin Falls County28302430Snake River Plain
Blaine County27302130Snake River Plain
Bonneville County27312816Snake River Plain
Butte County27332616Snake River Plain
Kootenai County27312030Rocky Mountains
Madison County27321930Snake River Plain
Latah County25292516Rocky Mountains
Boise County24331816Snake River Plain
Nez Perce County22281816Rocky Mountains

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

The physiographic regions inside Idaho

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

Snake River Plain

Basalt sits just below a loess cap. Excavating for a basement is expensive, and where one exists it often bears directly on rock — which does not move, but does not let water through either.

31 counties: Ada County, Bannock County, Bear Lake County, Bingham County, Blaine County, Boise County, Bonneville County, Butte County, Camas County, Canyon County, Caribou County, Cassia County, Clark County, Custer County, Elmore County, Franklin County, Fremont County, Gem County, Gooding County, Jefferson County, Jerome County, Lincoln County, Madison County, Minidoka County, Oneida County, Owyhee County, Payette County, Power County, Teton County, Twin Falls County, Washington County

Rocky Mountains

Shallow bedrock and coarse material. Basements are shallow or absent, and the problem is spring meltwater rather than a water table.

13 counties: Adams County, Benewah County, Bonner County, Boundary County, Clearwater County, Idaho County, Kootenai County, Latah County, Lemhi County, Lewis County, Nez Perce County, Shoshone County, Valley County

Page data updated