Excavation
Yard Drainage in Tigard, Oregon: Fixing a Soggy Lawn
Cojo
May 30, 2026
6 min read
If your Tigard lawn stays spongy from November into spring, you are dealing with a problem common across Washington County's suburban hills. The Tualatin basin collects steady Pacific rain through the wet season, and Tigard's neighborhoods sit on rolling clay-heavy terrain where water both falls from the sky and runs downhill from neighboring lots. Add clay soil that drains slowly, and standing water and saturated turf become a regular winter feature.
A soggy lawn is more than an eyesore. Constant saturation suffocates grass roots, invites moss, breeds mosquitoes, and — when the water collects near the house — can work toward the foundation. The good news is that a wet yard is solvable once you understand where the water comes from and where it can go.
This guide covers the local causes of poor yard drainage in Tigard and the solutions that hold up on clay and sloped lots. For statewide pricing, see our yard drainage cost guide for Oregon, and for the full system view, our overview of property and site drainage in Oregon.
Washington County's clay-rich soil holds water rather than letting it percolate down. Water that lands on the lawn — or arrives from uphill — lingers in the clay, keeping the turf saturated long after the rain stops.
Tigard's rolling terrain means many lots receive water flowing down from neighboring properties or higher ground. A lawn at the bottom of a gentle slope can be soggy not because of its own rainfall, but because it is collecting everyone else's. This is a defining difference from flat valley lots.
Foot traffic, mowing, and construction compact the soil and seal the surface. Compacted clay sheds water almost like pavement, sending it to the nearest low spot instead of soaking in evenly.
Roof runoff dumped at the foundation or onto the lawn overwhelms already-saturated soil. Routing that water away on solid pipe is often the cheapest, highest-impact first fix.
Because so many Tigard lots collect uphill water, a curtain drain across the high side of the yard — intercepting water before it reaches the lawn and house — is often the most effective fix. It stops the problem at the source rather than managing it after it arrives.
A gravel-filled trench with a perforated pipe intercepts subsurface water and carries it to a lower outfall. On Tigard clay, a French drain needs adequate depth, a clean gravel envelope, and filter fabric to keep silt out. It is the go-to solution for a chronically saturated lawn.
Reshaping the surface to create gentle fall toward a drainage point moves surface water off the lawn. A swale — a shallow, planted channel — can route water across a lot using the natural slope, often without a pipe.
For a specific low spot that collects water, a catch basin captures it and pipes it away, while a drywell can store and slowly release it where there is no gravity outfall. Wherever the drain ends, confirming a legal outfall is the first thing a contractor checks.
The right solution depends entirely on where your water comes from. A lot at the bottom of a slope receiving uphill runoff needs an interceptor drain, while a flat lot may just need regrading and a French drain. A property with a chronically wet low spot may need a catch basin and a drywell. The wrong fix simply moves the water a few feet.
That is why a site assessment matters more than any general advice. A drainage contractor who walks your property, checks the grade, traces where the water comes from, and finds your outfall options can design a system that solves the problem. On Tigard's slopes, the best fix often combines an interceptor to stop incoming water, a French drain for the subsurface, and a downspout reroute to cut the volume at the source.
Cojo Excavation & Asphalt fixes soggy lawns and standing water for Tigard and Washington County homeowners. We assess your grade, soil, incoming water, and outfall options on site, then deliver a clear, no-obligation quote for a system built for clay and sloped lots.
Request a free drainage estimate and we will respond within 24 hours. Learn more about our excavation services and how we keep Tigard yards dry through the wet season.
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