Soil series profile
Austin soil series
Austin is a well drained soil with a silty clay surface, mapped on 351,463 acres in 20 counties in TX. Hydrologic group D.
- Drainage class
- Well drained 100% of mapped acres
- Hydrologic group
- D 85% of mapped acres
- Typical topsoil pH
- 8.2 moderately alkaline · range 8.2–8.2
- Mapped area
- 351k acres in 20 counties, 1 state
Typical Austin profile
Texture and pH by depth
Show as a table
| Depth | Texture | pH | Clay | Sand | Organic matter |
|---|---|---|---|---|---|
| 0–16 in (Ap) | Silty clay | 8.2 | 45% | 7% | 2.5% |
| 16–22 in (Bw) | Silty clay | 8.2 | 45% | 7% | 0.75% |
| 22–29 in (Bk) | Silty clay | 8.2 | 45% | 7% | 0.5% |
| 29–57 in (Cr) | Bedrock | 8.2 | Not reported | Not reported | Not reported |

What this means
What Austin soil means for gardens, lawns and septic systems
For gardens
Typical topsoil in Austin 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 97% of mapped Austin 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 silty clay (95% of mapped Austin acres).
100% of mapped Austin acres is moderately well to excessively drained, which suits most garden plants.
For lawns and yards
On >99% 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 97% of the acres in mapped Austin soils very limited, 0% somewhat limited and 0% not limited (3% 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.
Where Austin soil is found
Mapped acres
Austin is mapped in Texas.
| County | Acres | Share of county land |
|---|---|---|
| Collin County, TX | 62,776 | 11.6% |
| Ellis County, TX | 55,597 | 9.3% |
| Dallas County, TX | 38,368 | 6.8% |
| Bell County, TX | 37,876 | 5.6% |
| Williamson County, TX | 34,955 | 4.9% |
| Grayson County, TX | 26,688 | 4.5% |
| Travis County, TX | 21,675 | 3.4% |
| Bexar County, TX | 18,001 | 2.3% |
| Hill County, TX | 15,577 | 2.5% |
| McLennan County, TX | 11,221 | 1.7% |
| Fannin County, TX | 6,470 | 1.1% |
| Lamar County, TX | 5,811 | 1.0% |
| Red River County, TX | 5,523 | 0.8% |
| Guadalupe County, TX | 3,385 | 0.7% |
| Falls County, TX | 3,070 | 0.6% |
| Comal County, TX | 1,954 | 0.5% |
| Medina County, TX | 1,285 | 0.2% |
| Delta County, TX | 784 | 0.5% |
| Denton County, TX | 227 | 0.0% |
| Hays County, TX | 218 | 0.1% |
Septic absorption fields
NRCS rating, share of Austin acres
Show as a table
| Category | Share of acres |
|---|---|
| Not limited | 0.0% |
| Somewhat limited | 0.0% |
| Very limited | 96.8% |
| Not rated | 3.2% |
Drainage, water table and flooding
Share of Austin 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 2–4% (median 2%).
- Topsoil organic matter
- Median 2.5%.
Drainage class
Show as a table
| 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
Show as a table
| Category | Share of acres |
|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 0.0% |
| B: moderate infiltration | 0.0% |
| C: slow infiltration | 15.4% |
| D: very slow infiltration (clayey, shallow or wet) | 84.5% |
| 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 | 0.2% |
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 Austin (component kind "Series") in SSURGO: 351,463 acres.
- Method
- Shares are by mapped acres of Austin components. The profile comes from the single largest Austin component. Full methodology.