Soil series profile

Cascade soil series

Cascade is a somewhat poorly drained soil with a silt loam surface, mapped on 46,035 acres in 4 counties in OR. Hydrologic group C.

#6312 by mapped area fine-silty Typic Fragiumbrepts (Inceptisols)

Drainage class: Somewhat poorly drained
Hydrologic group: C
Typical topsoil pH: 5.6
Mapped area: 46k

Typical Cascade 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 Cascade horizons (representative values)
Depth	Texture	pH	Clay	Sand	Organic matter
0–8 in (H1)	Silt loam	5.6	17%	14%	5.5%
8–27 in (H2)	Silt loam	5.6	24%	9%	2.25%
27–60 in (H3)	Silt loam	5.6	23%	10%	0.75%

Representative values from the most extensive Cascade map unit (Cascade silt loam, 15 to 30 percent slopes, survey area OR051). 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 Cascade soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Cascade soils is moderately acidic: pH 5.6. Many vegetables grow well here, and some gardens benefit from a little lime. Test before adding any.

Loamy topsoil (loam, silt loam and similar) covers 97% of mapped Cascade acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silt loam (97% of mapped Cascade acres).

100% of mapped Cascade 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.

For a septic system

For conventional septic absorption fields, NRCS rates 100% of the acres in mapped Cascade 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.

Generated from the mapped numbers above using fixed rules, not a site visit. See how these notes are written.

Where Cascade soil is found

Mapped acres

Cascade is mapped in Oregon.

Counties with the most mapped Cascade soil
County	Acres	Share of county land
Multnomah County, OR	20,986	7.8%
Clackamas County, OR	13,455	2.4%
Washington County, OR	9,458	2.4%
Columbia County, OR	2,136	0.6%

Septic absorption fields

NRCS rating, share of Cascade acres

Not limited 0%

Somewhat limited 0%

Very limited 100%

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

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Septic tank absorption field rating across mapped Cascade acres.
Category	Share of acres
Not limited	0.0%
Somewhat limited	0.0%
Very limited	100.0%

Drainage, water table and flooding

Share of Cascade acres

Depth to seasonal high water table: About 2.0 feet (24 in) (median where reported).
Flooding: Not mapped as flooding on most acres.
Slope: Typically 5–45% (median 12%).
Topsoil organic matter: Median 5.5%.

Drainage class

Excessively drained 0%

Somewhat excessively drained 0%

Well drained 0%

Moderately well drained 0%

Somewhat poorly drained 100%

Poorly drained 0%

Very poorly drained 0%

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

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Drainage class across mapped Cascade acres.
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

A: fast infiltration (mostly sandy or gravelly) 0%

B: moderate infiltration 0%

C: slow infiltration 100%

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%

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

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Hydrologic soil group across mapped Cascade acres.
Category	Share of acres
A: fast infiltration (mostly sandy or gravelly)	0.0%
B: moderate infiltration	0.0%
C: slow infiltration	100.0%
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	0.0%
C/D: D as is, C if drained	0.0%

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 Cascade (component kind "Series") in SSURGO: 46,035 acres.
Method: Shares are by mapped acres of Cascade components. The profile comes from the single largest Cascade component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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