Salem, Oregon: what the ground under the city is like
Salem sits in Marion County, on puget sound and willamette lowland. The soil mapped here is predominantly classified well drained — and that classification, not the rainfall total, is what decides how a basement behaves.
38% of the mapped soil area around Salem is wet enough that the USDA describes it as needing artificial drainage.
Linear extensibility 3.9% — moderate.
Shallowest annual water table around 85 cm (2.8 ft).
Values are for Marion County, which is what the soil survey resolves to. Full county report · soil map for a specific address.
The ground under Salem
Puget Sound and Willamette Lowland. Vashon glacial till and lacustrine silts, with a dense hardpan below
The one part of the West where basements are genuinely common — and the reason they leak is glacial: dense Vashon till under a permeable cap perches water just above it through the wet season. Volume change is low. Drainage, and hillside seepage, decide everything.
When it shows up here
| Water | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Ground movement | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
The opposite calendar to most of the country: the wet season runs from November to March and the summer is dry. A basement here is tested in January, not in April.
Climate pattern for this physiographic region, not a forecast for your house and not from the soil survey. It answers a question homeowners actually ask: when does this show up.
What repairs cost in Oregon
| Reference job | Modelled range |
|---|---|
| Interior drain along two walls + sump pump | $5,600–$12,050 |
| Exterior excavation of one 40 ft wall | $4,200–$12,000 |
| Underpinning on 10 piers | $16,650–$35,500 |
Regional factor for OR: ×1.11. Full cost breakdown for Oregon · run your own dimensions.
ZIP codes in Salem
97301, 97302, 97303, 97304, 97305, 97306, 97308, 97309, 97310, 97311, 97312, 97314, 97317
Soil does not stop at a city boundary, and neither does this data — every ZIP code above resolves to the same county soil survey. For the individual survey polygons around one address, use the soil map.
Questions about Salem
Is the soil the same everywhere in Salem?
No. These values describe Marion County as a whole, which is the unit the soil survey publishes. Within a city, map units change over a few hundred metres — the soil map draws the actual polygons around a point and is the honest answer for one address.
Which contractor should I call in Salem?
We do not rank or recommend individual firms and we are not one. What this page is for is knowing which kind of work the ground here points to before anyone quotes you, and which claim to check. If you want quotes, the form below passes your request to the named networks.
Does this replace an inspection?
No. It tells you what the ground is; an inspection tells you what your building is doing on it. The useful order is: read this, print the brief for your county, then have someone look.
Get quotes in Salem
We pass what you enter to the contractor networks listed below. You choose whether to hire anyone.
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