Soil series profile

Harlingen soil series

Harlingen is a moderately well drained soil with a clay surface, mapped on 97,902 acres in 2 counties in TX. Hydrologic group D.

#3577 by mapped area very-fine Sodic Haplusterts (Vertisols)

Drainage class
Moderately well drained
94% of mapped acres
Hydrologic group
D
94% of mapped acres
Typical topsoil pH
8.2
moderately alkaline · range 8.2–8.2
Mapped area
98k
acres in 2 counties, 1 state

Typical Harlingen profile

Texture and pH by depth

Typical Harlingen soil profile by depth 0 in 20 in 40 in 60 in 0–11 in · H1 · pH 8.2 · 55% clay Clay 11–35 in · H2 · pH 8.2 · 68% clay Clay 35–71 in · H3 · pH 8.2 · 63% clay Clay
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 Harlingen horizons (representative values)
Depth Texture pH Clay Sand Organic matter
0–11 in (H1) Clay 8.2 55% 17% 2%
11–35 in (H2) Clay 8.2 68% 10% 1.5%
35–71 in (H3) Clay 8.2 63% 11% 0.75%

Representative values from the most extensive Harlingen map unit (Harlingen clay, survey area TX061). Other map units of this series vary within the series range.

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

What this means

What Harlingen soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Harlingen soils is moderately alkaline: pH 8.2. 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).

Clayey topsoil covers 94% of mapped Harlingen acres. Clay holds water and nutrients but drains slowly and compacts if worked wet: add compost, avoid tilling soggy soil and consider raised beds. The most common surface texture is clay (94% of mapped Harlingen acres).

>99% of mapped Harlingen acres is moderately well to excessively drained, which suits most garden plants.

For lawns and yards

On 94% of mapped acres, rain soaks in slowly (hydrologic groups C and D, including dual groups that are D until drained). Expect runoff and puddles after heavy rain: core-aerate compacted lawns and keep ground sloping away from foundations.

For a septic system

For conventional septic absorption fields, NRCS rates 94% of the acres in mapped Harlingen soils very limited, 0% somewhat limited and 0% not limited (6% not rated, such as urban land, pits or water).

Where the soil is very limited (slow permeability, a high water table, flooding, shallow bedrock or steep slopes), alternative systems such as mound or sand-filter designs are common and cost more.

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 Harlingen soil is found

Mapped acres

Harlingen is mapped in Texas.

Counties with the most mapped Harlingen soil
County Acres Share of county land
Cameron County, TX 52,018 8.5%
Hidalgo County, TX 45,884 4.6%

Septic absorption fields

NRCS rating, share of Harlingen acres

Not limited 0%
Somewhat limited 0%
Very limited 94%
Not rated 6%
Septic tank absorption field rating across mapped Harlingen acres. Scale 0 to 100% of mapped land.
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Septic tank absorption field rating across mapped Harlingen acres.
CategoryShare of acres
Not limited0.0%
Somewhat limited0.0%
Very limited94.2%
Not rated5.8%

Drainage, water table and flooding

Share of Harlingen acres

Depth to seasonal high water table
None reported within about 6.5 feet (median where reported).
Flooding
Mapped as flooding on 5% of acres (0% occasional, 0% frequent).
Slope
Typically 0–0% (median 0%).
Topsoil organic matter
Median 2%.

Drainage class

Excessively drained 0%
Somewhat excessively drained 0%
Well drained 6%
Moderately well drained 94%
Somewhat poorly drained 0%
Poorly drained 0%
Very poorly drained 0%
Not rated <1%
Drainage class across mapped Harlingen acres. Scale 0 to 100% of mapped land.
Show as a table
Drainage class across mapped Harlingen acres.
CategoryShare of acres
Excessively drained0.0%
Somewhat excessively drained0.0%
Well drained5.5%
Moderately well drained94.2%
Somewhat poorly drained0.0%
Poorly drained0.0%
Very poorly drained0.0%
Not rated0.3%

Hydrologic soil group

A: fast infiltration (mostly sandy or gravelly) 0%
B: moderate infiltration 0%
C: slow infiltration 0%
D: very slow infiltration (clayey, shallow or wet) 94%
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%
Not rated 6%
Hydrologic soil group across mapped Harlingen acres. Scale 0 to 100% of mapped land.
Show as a table
Hydrologic soil group across mapped Harlingen acres.
CategoryShare of acres
A: fast infiltration (mostly sandy or gravelly)0.0%
B: moderate infiltration0.0%
C: slow infiltration0.0%
D: very slow infiltration (clayey, shallow or wet)94.2%
A/D: D as is, A if drained0.0%
B/D: D as is, B if drained0.0%
C/D: D as is, C if drained0.0%
Not rated5.8%

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 Harlingen (component kind "Series") in SSURGO: 97,902 acres.
Method
Shares are by mapped acres of Harlingen components. The profile comes from the single largest Harlingen component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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