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Connecticut soil by county

Across Connecticut's mapped land, shrink-swell clay limits houses without basements on under 1% and a shallow water table limits basements on 37%.

Highest clay shares: Capitol Planning Region (under 1%), Lower Connecticut River Valley Planning Region (under 1%), Naugatuck Valley Planning Region (under 1%), Greater Bridgeport Planning Region (0%), Northeastern Connecticut Planning Region (0%). Highest water-table shares: Northeastern Connecticut Planning Region (52%), Capitol Planning Region (40%), Northwest Hills Planning Region (40%), Southeastern Connecticut Planning Region (38%), Lower Connecticut River Valley Planning Region (38%).

Data as of September 22, 2026 · 9 planning regions

Capitol Planning Region: 0%Greater Bridgeport Planning Region: 0%Lower Connecticut River Valley Planning Region: 0%Naugatuck Valley Planning Region: 0%Northeastern Connecticut Planning Region: 0%Northwest Hills Planning Region: 0%South Central Connecticut Planning Region: 0%Southeastern Connecticut Planning Region: 0%Western Connecticut Planning Region: 0%
Expansive clay: share of mapped land where shrink-swell clay limits houses without basementsunder 10%10-25%25-40%40-60%60%+
Capitol Planning Region: 40%Greater Bridgeport Planning Region: 23%Lower Connecticut River Valley Planning Region: 38%Naugatuck Valley Planning Region: 37%Northeastern Connecticut Planning Region: 52%Northwest Hills Planning Region: 40%South Central Connecticut Planning Region: 23%Southeastern Connecticut Planning Region: 38%Western Connecticut Planning Region: 35%
High water table: share of mapped land where a shallow water table limits basementsunder 10%10-25%25-40%40-60%60%+

Every planning region in Connecticut

Select a column heading to sort.
Capitol Planning Region under 1% 40% 0% n/a 1966
Greater Bridgeport Planning Region 0% 23% 0% n/a 1959
Lower Connecticut River Valley Planning Region under 1% 38% 0% n/a 1972
Naugatuck Valley Planning Region under 1% 37% 0% n/a 1969
Northeastern Connecticut Planning Region 0% 52% 0% n/a 1973
Northwest Hills Planning Region 0% 40% 0% n/a 1967
South Central Connecticut Planning Region 0% 23% 0% n/a 1964
Southeastern Connecticut Planning Region 0% 38% 0% n/a 1969
Western Connecticut Planning Region 0% 35% 0% n/a 1971

How these shares are counted

Shares are of mapped land in USDA's soil survey (SSURGO), weighted by each soil's share of every map unit. Drought is the US Drought Monitor's D1-or-worse share on the September 22, 2026 map. Flood losses are FEMA NFIP records since 2016. Sources and methods.