Soil series profile

Gunsight soil series

Gunsight is a somewhat excessively drained soil with a gravelly loam surface, mapped on 1,304,382 acres in 8 counties across 2 states. Hydrologic group A.

#105 by mapped area loamy-skeletal Typic Haplocalcids (Aridisols)

Drainage class: Somewhat excessively drained
Hydrologic group: A
Typical topsoil pH: 8.2
Mapped area: 1.3M

Typical Gunsight profile

Texture and pH by depth

Depth to scale. More strongly shaded layers hold more clay. Horizon names are the soil survey's (A = topsoil, B = subsoil, C = parent material).

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Typical Gunsight horizons (representative values)
Depth	Texture	pH	Clay	Sand	Organic matter
0–1 in (A)	Gravelly loam	8.4	11%	46%	0.3%
1–14 in (Bk1)	Very gravelly sandy loam	8.4	11%	66%	0.2%
14–35 in (Bk2)	Extremely gravelly sandy loam	8.2	11%	66%	0.2%
35–60 in (Bk3)	Extremely gravelly sandy loam	8.0	11%	66%	0.2%

Representative values from the most extensive Gunsight map unit (Gunsight-Cristobal complex, dry, 1 to 10 percent slopes, survey area AZ657). Other map units of this series vary within the series range.

Stock photo for illustration, not a sample of this soil series. Credit on the Sources & method page.

What this means

What Gunsight soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Gunsight soils is moderately alkaline: pH 8.2 (most land between 8.0 and 8.5). Acid-loving plants such as blueberries and azaleas struggle without amended beds, and some trees and shrubs show iron chlorosis (yellow leaves with green veins).

Loamy topsoil (loam, silt loam and similar) covers 99% of mapped Gunsight acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is very gravelly sandy loam (21% of mapped Gunsight acres).

88% of mapped Gunsight acres is excessively or somewhat excessively drained: water moves through fast, so gardens need more frequent watering in dry spells.

For lawns and yards

78% of mapped acres is in hydrologic group A, where water soaks in fast. Lawns there dry out quickly; deeper, less frequent watering and organic matter help.

For a septic system

For conventional septic absorption fields, NRCS rates 18% of the acres in mapped Gunsight soils very limited, 29% somewhat limited and 53% not limited.

Only a licensed site evaluation or perc test at the actual lot decides whether a system is allowed and which design.

Generated from the mapped numbers above using fixed rules, not a site visit. See how these notes are written.

Where Gunsight soil is found

Mapped acres

Gunsight is mapped in Arizona and California.

Counties with the most mapped Gunsight soil
County	Acres	Share of county land
La Paz County, AZ	377,040	13.4%
Maricopa County, AZ	311,650	5.0%
Yuma County, AZ	294,540	13.2%
Pima County, AZ	125,596	2.4%
Mohave County, AZ	113,292	1.3%
Pinal County, AZ	34,158	1.0%
San Bernardino County, CA	11,480	0.2%
Riverside County, CA	196	0.0%

Septic absorption fields

NRCS rating, share of Gunsight acres

Not limited 53%

Somewhat limited 29%

Very limited 18%

Septic tank absorption field rating across mapped Gunsight acres. Scale 0 to 100% of mapped land.

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Septic tank absorption field rating across mapped Gunsight acres.
Category	Share of acres
Not limited	52.8%
Somewhat limited	29.4%
Very limited	17.9%

Drainage, water table and flooding

Share of Gunsight acres

Depth to seasonal high water table: None reported within about 6.5 feet (median where reported).
Flooding: Not mapped as flooding on most acres.
Slope: Typically 4–25% (median 8%).
Topsoil organic matter: Median 0.3%.

Drainage class

Excessively drained 0%

Somewhat excessively drained 88%

Well drained 12%

Moderately well drained 0%

Somewhat poorly drained 0%

Poorly drained 0%

Very poorly drained 0%

Drainage class across mapped Gunsight acres. Scale 0 to 100% of mapped land.

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Drainage class across mapped Gunsight acres.
Category	Share of acres
Excessively drained	0.0%
Somewhat excessively drained	87.8%
Well drained	12.2%
Moderately well drained	0.0%
Somewhat poorly drained	0.0%
Poorly drained	0.0%
Very poorly drained	0.0%

Hydrologic soil group

A: fast infiltration (mostly sandy or gravelly) 78%

B: moderate infiltration 22%

C: slow infiltration 0%

D: very slow infiltration (clayey, shallow or wet) 0%

A/D: D as is, A if drained 0%

B/D: D as is, B if drained 0%

C/D: D as is, C if drained 0%

Hydrologic soil group across mapped Gunsight acres. Scale 0 to 100% of mapped land.

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Hydrologic soil group across mapped Gunsight acres.
Category	Share of acres
A: fast infiltration (mostly sandy or gravelly)	78.2%
B: moderate infiltration	21.8%
C: slow infiltration	0.0%
D: very slow infiltration (clayey, shallow or wet)	0.0%
A/D: D as is, A if drained	0.0%
B/D: D as is, B if drained	0.0%
C/D: D as is, C if drained	0.0%

Sources & data dates

Source: USDA NRCS Soil Survey Geographic Database (SSURGO), queried through Soil Data Access. Public domain.
Data date: SSURGO as published on November 3, 2026 (most recent survey area update October 26, 2026). NRCS refreshes SSURGO each October.
Scope: All map unit components named Gunsight (component kind "Series") in SSURGO: 1,304,382 acres.
Method: Shares are by mapped acres of Gunsight components. The profile comes from the single largest Gunsight component. Full methodology.

Independent reference site. No government affiliation or endorsement.

Full narrative description: USDA Official Soil Series Description for Gunsight.