Soil and perc tests in Bastrop County, Texas

What is a perc test and does Bastrop County require one?

Yes. Texas requires a site evaluation before it issues a permit.

A site evaluator or an engineer checks the soil in two pits or borings. The evaluator also checks for shallow groundwater and reviews slope and flood risk. The county uses this report to set the system's size.

Texas Administrative Code, Title 30, Chapter 285, Section 285.30, Site Evaluation · checked 2026-09-23

How USDA rates the ground in Bastrop County

Very limited across most of the county — 80.3% of the rated acres. A rating describes the ground, not a parcel. The county's site evaluation decides each lot.

• Very limited — 406,310 acres — 80.3% of 505,952 rated acres.
• Somewhat limited — 99,642 acres — 19.7% of 505,952 rated acres.
• Not rated — 68,122 acres, excluded from the denominator — mostly urban land and water.

80.3% of 505,952 rated acres. 68,122 acres unrated. Survey area TX021 version 24, established 2026-09-03.

USDA NRCS Soil Data Access (SSURGO) · checked 2026-10-06

What limits absorption here

The reasons USDA gives for the rating, by the acres they affect. A component can carry several, so the acres overlap.

• Slow water movement — 485,492 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
• Depth to bedrock — 98,306 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
• Depth to saturated zone — 80,242 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
• Flooding — 63,522 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
• Slope — 21,936 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
• Seepage, bottom layer — 21,501 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
• Filtering capacity — 20,460 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
• Ponding — 94 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.

Ratings by soil map unit

The largest map units in the county, each with its rating. A soil survey names the ground. The county's evaluation of your lot is what a permit turns on.

• PaE — Padina fine sand, 1 to 12 percent slopes — 59,520 acres in this county — rated Somewhat limited. Dominant component: Padina (95% of the map unit).
• DeC — Robco-Tanglewood complex, 1 to 5 percent slopes — 45,919 acres in this county — rated Very limited. Dominant component: Robco (46% of the map unit).
• CsC2 — Crockett fine sandy loam, 2 to 5 percent slopes, eroded — 45,004 acres in this county — rated Very limited. Dominant component: Crockett (85% of the map unit).
• AfC — Edge fine sandy loam, 1 to 5 percent slopes — 42,818 acres in this county — rated Very limited. Dominant component: Edge (90% of the map unit).
• AtD — Edge gravelly fine sandy loam, 3 to 8 percent slopes — 38,784 acres in this county — rated Very limited. Dominant component: Edge (95% of the map unit).
• TfB — Tabor fine sandy loam, 1 to 3 percent slopes — 37,513 acres in this county — rated Very limited. Dominant component: Tabor (85% of the map unit).
• AfC2 — Edge fine sandy loam, 2 to 5 percent slopes, moderately eroded — 34,315 acres in this county — rated Very limited. Dominant component: Edge (90% of the map unit).
• SkC — Silstid loamy fine sand, 1 to 5 percent slopes — 26,517 acres in this county — rated Somewhat limited. Dominant component: Silstid (85% of the map unit).

USDA NRCS Soil Data Access (SSURGO) · checked 2026-10-06

Sources

Each figure on this page has a government source and a checked-on date.

1. Bastrop County Development Services — On-Site Sewage Facilities · checked 2026-10-05
2. Bastrop County On-Site Sewage Facility Rules (TCEQ-approved order), Section 10.5 · checked 2026-10-05
3. Bastrop County Development Services — OSSF Application and Application Fees (rev. 2024-06-20) · checked 2026-10-05
4. Texas Administrative Code, Title 30, Chapter 285, Section 285.30, Site Evaluation · checked 2026-09-23
5. Bastrop County — My Government Online Step by Step Guide · checked 2026-10-05
6. USDA NRCS Soil Data Access (SSURGO) · checked 2026-10-06

Related pages

• Septic rules and requirements in Bastrop County, Texas
• Septic permits and fees in Bastrop County, Texas
• Septic rules and requirements in Texas
• Septic rules in Bastrop County