What's My Soil

A field guide to the soil under your feet

Soil series profile

Ririe soil series

Ririe is a well drained soil with a silt loam surface, mapped on 278,362 acres in 14 counties across 3 states. Hydrologic group B.

#1242 by mapped area coarse-silty Calcic Haploxerolls (Mollisols)

Drainage class
Well drained
>99% of mapped acres
Hydrologic group
B
78% of mapped acres
Typical topsoil pH
7.5
slightly alkaline · range 7.5–7.6
Mapped area
278k
acres in 14 counties, 3 states

Typical Ririe profile

Texture and pH by depth

Typical Ririe soil profile by depth 0 in 10 in 20 in 30 in 40 in 50 in 0–8 in · A · pH 7.5 · 17% clay Silt loam 8–15 in · Bw · pH 8.2 · 15% clay Silt loam 15–29 in · Bk1 · pH 8.2 · 15% clay Silt loam 29–42 in · Bk2 · pH 8.2 · 15% clay Silt loam 42–60 in · Bk3 · pH 8.2 · 15% clay Silt loam
Depth to scale. More strongly shaded layers hold more clay. Horizon names are the soil survey's (A = topsoil, B = subsoil, C = parent material).
Show as a table
Typical Ririe horizons (representative values)
Depth Texture pH Clay Sand Organic matter
0–8 in (A) Silt loam 7.5 17% 14% 3%
8–15 in (Bw) Silt loam 8.2 15% 14% 0.75%
15–29 in (Bk1) Silt loam 8.2 15% 14% 0.75%
29–42 in (Bk2) Silt loam 8.2 15% 14% 0.75%
42–60 in (Bk3) Silt loam 8.2 15% 14% 0.75%

Representative values from the most extensive Ririe map unit (Ririe silt loam, 4 to 12 percent slopes, survey area ID769). Other map units of this series vary within the series range.

Hands holding dark garden soil
Stock photo for illustration, not a sample of this soil series. Credit on the Sources & method page.

What this means

What Ririe soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Ririe soils is slightly alkaline: pH 7.5 (most land between 7.5 and 7.6). 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).

Loamy topsoil (loam, silt loam and similar) covers >99% of mapped Ririe acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silt loam (>99% of mapped Ririe acres).

>99% of mapped Ririe 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 26% of the acres in mapped Ririe soils very limited, 74% somewhat limited and 0% not limited.

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 Ririe soil is found

Mapped acres

Ririe is mapped in Idaho, Wyoming and Utah.

Counties with the most mapped Ririe soil
County Acres Share of county land
Bonneville County, ID 76,476 6.9%
Caribou County, ID 44,275 3.8%
Madison County, ID 42,572 13.6%
Oneida County, ID 17,367 2.7%
Fremont County, ID 15,091 1.4%
Teton County, ID 14,502 5.5%
Cassia County, ID 14,469 1.4%
Bannock County, ID 10,263 2.6%
Bear Lake County, ID 1,224 0.2%
Teton County, WY 185 0.0%
Power County, ID 37 0.0%
Lincoln County, WY 12 0.0%
Rich County, UT 10 0.0%
Franklin County, ID 7 0.0%

Septic absorption fields

NRCS rating, share of Ririe acres

Not limited 0%
Somewhat limited 74%
Very limited 26%
Not rated <1%
Septic tank absorption field rating across mapped Ririe acres. Scale 0 to 100% of mapped land.
Show as a table
Septic tank absorption field rating across mapped Ririe acres.
CategoryShare of acres
Not limited0.0%
Somewhat limited73.8%
Very limited26.1%
Not rated0.1%

Drainage, water table and flooding

Share of Ririe 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 3–16% (median 8%).
Topsoil organic matter
Median 3%.

Drainage class

Excessively drained 0%
Somewhat excessively drained 0%
Well drained >99%
Moderately well drained 0%
Somewhat poorly drained 0%
Poorly drained 0%
Very poorly drained 0%
Not rated <1%
Drainage class across mapped Ririe acres. Scale 0 to 100% of mapped land.
Show as a table
Drainage class across mapped Ririe acres.
CategoryShare of acres
Excessively drained0.0%
Somewhat excessively drained0.0%
Well drained99.9%
Moderately well drained0.0%
Somewhat poorly drained0.0%
Poorly drained0.0%
Very poorly drained0.0%
Not rated0.1%

Hydrologic soil group

A: fast infiltration (mostly sandy or gravelly) 0%
B: moderate infiltration 78%
C: slow infiltration 22%
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 <1%
Hydrologic soil group across mapped Ririe acres. Scale 0 to 100% of mapped land.
Show as a table
Hydrologic soil group across mapped Ririe acres.
CategoryShare of acres
A: fast infiltration (mostly sandy or gravelly)0.0%
B: moderate infiltration77.9%
C: slow infiltration22.0%
D: very slow infiltration (clayey, shallow or wet)0.0%
A/D: D as is, A if drained0.0%
B/D: D as is, B if drained0.0%
C/D: D as is, C if drained0.0%
Not rated0.1%

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 Ririe (component kind "Series") in SSURGO: 278,362 acres.
Method
Shares are by mapped acres of Ririe components. The profile comes from the single largest Ririe component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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