Soil series profile

Conroe soil series

Conroe is a moderately well drained soil with a loamy fine sand surface, mapped on 149,888 acres in 7 counties in TX. Hydrologic group B.

#2465 by mapped area clayey Arenic Plinthic Paleudults (Ultisols)

Drainage class: Moderately well drained
Hydrologic group: B
Typical topsoil pH: 5.5
Mapped area: 150k

Typical Conroe 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 Conroe horizons (representative values)
Depth	Texture	pH	Clay	Sand	Organic matter
0–25 in (H1)	Loamy fine sand	5.5	6%	78%	1.5%
25–31 in (H2)	Sandy clay loam	5.0	35%	52%	0.75%
31–78 in (H3)	Clay	5.0	43%	28%	0.75%
78–80 in (H4)	Sandy clay	5.0	38%	51%	0.3%

Representative values from the most extensive Conroe map unit (Conroe loamy fine sand, 0 to 5 percent slopes, survey area TX339). 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 Conroe soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Conroe soils is strongly acidic: pH 5.5 (most land between 4.5 and 5.5). Most vegetables and lawn grasses do best around 6.0 to 7.0, so lime is often needed; blueberries, azaleas and rhododendrons like it as it is.

Sandy topsoil covers 90% of mapped Conroe acres. It drains fast and warms early in spring, but dries out and loses nutrients quickly: mulch, compost and steady watering help. The most common surface texture is loamy fine sand (58% of mapped Conroe acres).

100% of mapped Conroe 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 92% of the acres in mapped Conroe soils very limited, 0% somewhat limited and 0% not limited (8% 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 Conroe soil is found

Mapped acres

Conroe is mapped in Texas.

Counties with the most mapped Conroe soil
County	Acres	Share of county land
Montgomery County, TX	101,338	15.2%
San Jacinto County, TX	27,889	7.7%
Walker County, TX	13,464	2.7%
Waller County, TX	4,199	1.3%
Grimes County, TX	2,766	0.5%
Polk County, TX	220	0.0%
Austin County, TX	12	0.0%

Septic absorption fields

NRCS rating, share of Conroe acres

Not limited 0%

Somewhat limited 0%

Very limited 92%

Not rated 8%

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

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Septic tank absorption field rating across mapped Conroe acres.
Category	Share of acres
Not limited	0.0%
Somewhat limited	0.0%
Very limited	91.9%
Not rated	8.1%

Drainage, water table and flooding

Share of Conroe acres

Depth to seasonal high water table: About 2.6 feet (31 in) (median where reported).
Flooding: Not mapped as flooding on most acres.
Slope: Typically 3–3% (median 3%).
Topsoil organic matter: Median 1.5%.

Drainage class

Excessively drained 0%

Somewhat excessively drained 0%

Well drained 0%

Moderately well drained 100%

Somewhat poorly drained 0%

Poorly drained 0%

Very poorly drained 0%

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

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Drainage class across mapped Conroe acres.
Category	Share of acres
Excessively drained	0.0%
Somewhat excessively drained	0.0%
Well drained	0.0%
Moderately well drained	100.0%
Somewhat poorly drained	0.0%
Poorly drained	0.0%
Very poorly drained	0.0%

Hydrologic soil group

A: fast infiltration (mostly sandy or gravelly) 3%

B: moderate infiltration 85%

C: slow infiltration 0%

D: very slow infiltration (clayey, shallow or wet) 4%

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 8%

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

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Hydrologic soil group across mapped Conroe acres.
Category	Share of acres
A: fast infiltration (mostly sandy or gravelly)	2.7%
B: moderate infiltration	85.3%
C: slow infiltration	0.0%
D: very slow infiltration (clayey, shallow or wet)	3.9%
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	8.1%

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 Conroe (component kind "Series") in SSURGO: 149,888 acres.
Method: Shares are by mapped acres of Conroe components. The profile comes from the single largest Conroe component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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