Septic companies in Lake Oswego, OR

What the ground in Lake Oswego is like

The USDA soil survey rates mapped ground in Lake Oswego for septic drain-field suitability across roughly 11 square miles. About 100% of the rated ground is classed "Very limited", the survey records severe restrictions for a conventional drain field across most of that ground.

In Lake Oswego, the leading limit is slow water movement: effluent does not drain through the soil fast enough, so a conventional field can back up or pond when the ground cannot keep pace. The survey flags that limit on about 73% of the rated ground here.

The limiting features the survey records most often here:

• Slow water movement72.7%
• Depth to saturated zone66.1%
• Slope59.3%
• Seepage, bottom layer15.0%

This is survey data for mapped areas, not a substitute for a site evaluation on your own lot. Conditions on a single parcel can differ from the map.

USDA NRCS SSURGO, ENG Septic Tank Absorption Fields · 99.7% Very limited · Slow water movement · 74 map units · 10.88 sq mi · read 2026-08-30