Soil series profile
Flanagan soil series
Flanagan is a somewhat poorly drained soil with a silt loam surface, mapped on 662,720 acres in 22 counties across 2 states. Hydrologic group C/D.
- Drainage class
- Somewhat poorly drained 100% of mapped acres
- Hydrologic group
- C/D 92% of mapped acres
- Typical topsoil pH
- 6.2 slightly acidic · range 6.2–6.2
- Mapped area
- 663k acres in 22 counties, 2 states
Typical Flanagan profile
Texture and pH by depth
Show as a table
| Depth | Texture | pH | Clay | Sand | Organic matter |
|---|---|---|---|---|---|
| 0–8 in (Ap) | Silt loam | 6.2 | 24% | 5% | 4% |
| 8–18 in (A) | Silty clay loam | 6.2 | 29% | 5% | 3% |
| 18–32 in (Bt1) | Silty clay loam | 5.8 | 37% | 5% | 1% |
| 32–45 in (Bt2) | Silty clay loam | 6.2 | 32% | 8% | 0.5% |
| 45–49 in (2Bt3) | Silt loam | 7.0 | 25% | 25% | 0.3% |
| 49–60 in (2C) | Loam | 7.9 | 19% | 37% | 0.2% |
What this means
What Flanagan soil means for gardens, lawns and septic systems
For gardens
Typical topsoil in Flanagan soils is slightly acidic: pH 6.2, the range most vegetables, flowers and lawn grasses prefer.
Loamy topsoil (loam, silt loam and similar) covers 100% of mapped Flanagan acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silt loam (100% of mapped Flanagan acres).
100% of mapped Flanagan acres is somewhat poorly to very poorly drained, so soil stays soggy for long spells after rain and in wet seasons. Raised beds, plants that tolerate wet feet, and not working the soil while wet all help.
For lawns and yards
On 100% 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.
A seasonal high water table comes within 18 inches of the surface on 95% of mapped acres, often in spring. Basements, sump pumps and lawns in low spots feel it first.
For a septic system
For conventional septic absorption fields, NRCS rates 100% of the acres in mapped Flanagan soils very limited, 0% somewhat limited and 0% not limited.
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 Flanagan soil is found
Mapped acres
Flanagan is mapped in Illinois and Indiana.
| County | Acres | Share of county land |
|---|---|---|
| Champaign County, IL | 95,515 | 15.0% |
| Macon County, IL | 67,497 | 18.3% |
| Moultrie County, IL | 63,650 | 29.8% |
| DeKalb County, IL | 54,151 | 13.5% |
| Piatt County, IL | 53,962 | 19.3% |
| Vermilion County, IL | 52,662 | 9.3% |
| Douglas County, IL | 51,145 | 19.2% |
| Edgar County, IL | 47,320 | 11.9% |
| Shelby County, IL | 33,262 | 6.9% |
| Woodford County, IL | 31,271 | 9.5% |
| LaSalle County, IL | 31,010 | 4.4% |
| Coles County, IL | 22,381 | 6.9% |
| McLean County, IL | 19,225 | 2.6% |
| Marshall County, IL | 11,242 | 4.6% |
| Lee County, IL | 5,554 | 1.2% |
| Vermillion County, IN | 4,611 | 2.9% |
| Stark County, IL | 4,534 | 2.5% |
| Kane County, IL | 3,996 | 1.2% |
| Bureau County, IL | 3,918 | 0.7% |
| Ogle County, IL | 2,893 | 0.6% |
| Putnam County, IL | 2,155 | 2.2% |
| Kendall County, IL | 767 | 0.4% |
Septic absorption fields
NRCS rating, share of Flanagan acres
Show as a table
| Category | Share of acres |
|---|---|
| Not limited | 0.0% |
| Somewhat limited | 0.0% |
| Very limited | 100.0% |
Drainage, water table and flooding
Share of Flanagan acres
- Depth to seasonal high water table
- About 1.5 feet (18 in) (median where reported); within 18 inches on 95% of acres.
- Flooding
- Not mapped as flooding on most acres.
- Slope
- Typically 1–1% (median 1%).
- Topsoil organic matter
- Median 4%.
Drainage class
Show as a table
| Category | Share of acres |
|---|---|
| Excessively drained | 0.0% |
| Somewhat excessively drained | 0.0% |
| Well drained | 0.0% |
| Moderately well drained | 0.0% |
| Somewhat poorly drained | 100.0% |
| 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 | 5.0% |
| 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 | 2.9% |
| C/D: D as is, C if drained | 92.1% |
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 Flanagan (component kind "Series") in SSURGO: 662,720 acres.
- Method
- Shares are by mapped acres of Flanagan components. The profile comes from the single largest Flanagan component. Full methodology.