USDA SSURGO COUNTY SOIL REFERENCE

Pima County, Arizona Soil Summary

This page summarizes USDA SSURGO mapped soil information for Pima County, Arizona.

Mapped Land Coverage
99.98%5,880,856.62 mapped acres of 5,882,026.56 Census land acres

Coverage measures mapped SSURGO intersection with Census land geometry. It does not mean that every parcel or point has complete soil information.

Soil at a Glance

Largest mapped soil unit
Lithic Argiustolls, Typic Haplustolls, and Aridic Calciustolls; warm mesic ustic mountains
Symbol: 2075.77% of mapped area
Largest estimated component
Unnamed soils
622,944.65 acres (10.59% of mapped area)
Mapped units & components
15 soil units • 15 component series
Distinct SSURGO map units & series
Dominant drainage class
Well drained
Highest acreage drainage class
Dominant hydrologic group
Group D
Runoff potential classification
Weighted average slope
13.31%
Terrain slope analysis
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County summaries provide regional context across mapped soil units. Address lookup combines available public datasets for the Census-matched location.

Mapped SSURGO Soil Units

Largest mapped soil units in Pima County ranked by intersected vector acreage
SymbolMap Unit NameMapped Acres% of Mapped Area
207Lithic Argiustolls, Typic Haplustolls, and Aridic Calciustolls; warm mesic ustic mountains339,490.025.77%
7Dateland, Wellton, Rillito, Denure, and Rositas, dry, 0 to 5 percent slopes141,276.232.4%
6Bucklebar-Hayhook-Tubac complex, 0 to 3 percent slopes119,524.632.03%
12Lomitas, Rock outcrop, Quilotosa, and Rizzo, dry, 15 to 65 percent slopes107,077.451.82%
10Growler, Mohall, Tucson, and Valencia, occasionally flooded, dry, 1 to 3 percent slopes102,953.91.75%
5Coolidge, Denure, and Rillito, dry, 0 to 5 percent slopes96,725.271.64%
25Tremant, Casa Grande, and Rositas, rarely flooded, occasionally ponded, dry, 0 to 10 percent slopes96,673.731.64%
204Calcic Petrocalcids, Typic Haplocalcids, and Lithic Ustic Torriorthents; cool thermic aridic fan remnants and hills94,715.291.61%
21Denure-Rillito-Why complex, 1 to 5 percent slopes86,075.541.46%
6Coolidge, Denure, and Rillito, dry, 0 to 5 percent slopes83,092.721.41%
45Nahda-Stagecoach complex, 1 to 15 percent slopes72,458.941.23%
44Mohall-Trix complex, 0 to 1 percent slopes69,425.651.18%
21Lomitas, Rock outcrop, Quilotosa, and Rizzo, dry, 15 to 65 percent slopes66,398.21.13%
24Superstition, Rositas, and Tucson, dry, 0 to 10 percent slopes65,561.911.11%
13Gunsight, Chuckawalla, and Carrizo, occasionally flooded, dry, 1 to 10 percent slopes64,743.681.1%

Estimated Soil Components

Component acreage estimated from SSURGO component percentages
ComponentDrainage ClassHydrologic GroupEstimated Acres% of Mapped Area
Unnamed soilsUnspecifiedUnspecified622,944.6510.59%
Rock outcropUnspecifiedD291,044.824.95%
DenureWell drained, Somewhat excessively drainedB, A227,849.63.87%
Lithic ArgiustollsWell drainedD222,836.953.79%
RillitoWell drained, Somewhat excessively drainedB, A174,720.552.97%
GunsightSomewhat excessively drainedB, A168,311.912.86%
MohallWell drainedC131,385.62.23%
CarrizoExcessively drainedA121,709.052.07%
Typic HaplustollsWell drainedC119,5702.03%
QuilotosaSomewhat excessively drainedD101,802.281.73%
CoolidgeWell drainedB, A101,656.181.73%
LampshireWell drainedD96,873.131.65%
RositasSomewhat excessively drainedA95,685.161.63%
CaralampiWell drainedC89,634.21.52%
DatelandWell drainedB, A87,804.021.49%
Component acreage is estimated from SSURGO map-unit component percentages. Component values are not independently mapped polygon boundaries.

Drainage Class Distribution

Well drained59.55%
3,501,790.85 acres
Somewhat excessively drained20.06%
1,179,532.04 acres
Unknown / Unmapped16.7%
981,834.07 acres
Excessively drained3.5%
205,733.3 acres
Moderately well drained0.17%
9,995.83 acres
Somewhat poorly drained0.03%
1,970.52 acres

Hydrologic Soil Group Distribution

Group D28.48%
1,674,916.43 acres
Group A26.6%
1,564,464.62 acres
Group C22.38%
1,315,868.81 acres
Group Unknown / Unmapped13.22%
777,207.56 acres
Group B9.33%
548,399.2 acres

Hydrologic soil groups are USDA/NRCS classifications related to runoff potential under specified soil conditions. They are not a property-level flood-risk rating.

Slope Characteristics

Weighted Average Slope: 13.31%
Nearly Level (0-2%)27.63%
1,624,793.59 acres
Gently Sloping (2-8%)21.87%
1,286,128.96 acres
Moderately Sloping (8-15%)10.82%
636,295.21 acres
Steep (15-30%)7.02%
412,983.18 acres
Very Steep (>30%)16.27%
956,687.71 acres
Unspecified Slope16.39%
963,967.97 acres

Sources & Methodology

USDA NRCS SSURGO

Mapped soil units, components, drainage classes, hydrologic groups, and slope ratings derived from official Soil Data Access REST services.

U.S. Census Bureau TIGER/Line

County land geometry used for county-level coverage calculation.

Coverage Method

Mapped acreage is calculated from true spatial vector intersection of county land geometry and SSURGO mapped soil polygons using NAD83 / CONUS Albers Equal Area projection (EPSG:5070).