Soil series profile

Brennan soil series

Brennan is a well drained soil with a fine sandy loam surface, mapped on 273,480 acres in 15 counties in TX. Hydrologic group B.

#1269 by mapped area fine-loamy Aridic Haplustalfs (Alfisols)

Drainage class: Well drained
Hydrologic group: B
Typical topsoil pH: 7.2
Mapped area: 273k

Typical Brennan 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 Brennan horizons (representative values)
Depth	Texture	pH	Clay	Sand	Organic matter
0–12 in (A)	Fine sandy loam	7.2	13%	67%	0.75%
12–26 in (Bt)	Sandy clay loam	7.9	24%	58%	0.55%
26–40 in (Bk)	Sandy clay loam	8.0	22%	66%	0.25%
40–80 in (BCk)	Sandy clay loam	8.2	20%	70%	0.15%

Representative values from the most extensive Brennan map unit (Brennan fine sandy loam, 0 to 1 percent slopes, survey area TX215). 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 Brennan soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Brennan soils is neutral: pH 7.2, the range most vegetables, flowers and lawn grasses prefer.

Loamy topsoil (loam, silt loam and similar) covers 93% of mapped Brennan acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is fine sandy loam (93% of mapped Brennan acres).

100% of mapped Brennan acres is moderately well to excessively drained, which suits most garden plants.

For lawns and yards

Most land is in hydrologic groups B and C, where rain soaks in at a moderate pace.

For a septic system

For conventional septic absorption fields, NRCS rates 2% of the acres in mapped Brennan soils very limited, 92% somewhat limited and 0% not limited (7% not rated, such as urban land, pits or water).

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 Brennan soil is found

Mapped acres

Brennan is mapped in Texas.

Counties with the most mapped Brennan soil
County	Acres	Share of county land
Hidalgo County, TX	93,464	9.3%
Zapata County, TX	69,076	10.5%
Starr County, TX	55,167	7.0%
Jim Hogg County, TX	42,053	5.8%
McMullen County, TX	6,513	0.9%
Duval County, TX	2,570	0.2%
Webb County, TX	2,259	0.1%
Zavala County, TX	1,337	0.2%
Brooks County, TX	479	0.1%
Frio County, TX	199	0.0%
Dimmit County, TX	126	0.0%
Cameron County, TX	97	0.0%
Jim Wells County, TX	79	0.0%
Willacy County, TX	30	0.0%
La Salle County, TX	29	0.0%

Septic absorption fields

NRCS rating, share of Brennan acres

Not limited 0%

Somewhat limited 92%

Very limited 2%

Not rated 7%

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

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Septic tank absorption field rating across mapped Brennan acres.
Category	Share of acres
Not limited	0.0%
Somewhat limited	91.8%
Very limited	1.5%
Not rated	6.7%

Drainage, water table and flooding

Share of Brennan 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 0–2% (median 0%).
Topsoil organic matter: Median 0.8%.

Drainage class

Excessively drained 0%

Somewhat excessively drained 0%

Well drained 100%

Moderately well drained 0%

Somewhat poorly drained 0%

Poorly drained 0%

Very poorly drained 0%

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

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Drainage class across mapped Brennan acres.
Category	Share of acres
Excessively drained	0.0%
Somewhat excessively drained	0.0%
Well drained	100.0%
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) 0%

B: moderate infiltration 92%

C: slow infiltration 2%

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%

Not rated 7%

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

Show as a table

Hydrologic soil group across mapped Brennan acres.
Category	Share of acres
A: fast infiltration (mostly sandy or gravelly)	0.0%
B: moderate infiltration	91.8%
C: slow infiltration	1.5%
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%
Not rated	6.7%

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 Brennan (component kind "Series") in SSURGO: 273,480 acres.
Method: Shares are by mapped acres of Brennan components. The profile comes from the single largest Brennan component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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