Yard Drainage in Portland, Oregon: Fixing a Soggy Lawn

The Portland Swamp Lawn

If your Portland lawn turns into a squelching mess every winter and stays that way for weeks, you're in good company. Soggy yards are one of the most common property complaints across the city, and the reasons are baked into Portland's geography: months of steady rain landing on heavy Multnomah County clay that won't let it soak away. The water has nowhere to go, so it sits — on your grass, in the low spots, and sometimes right up against the house.

The encouraging news is that a soggy Portland lawn is a solvable problem with the right approach. The catch is that the right approach for Portland's clay is different from the generic advice you'll find online. This guide explains why Portland yards stay wet and the solutions that actually work here. For pricing detail, our yard drainage cost guide is the parent resource, and property & site drainage in Oregon gives the full overview.

Why Portland Lawns Stay Wet

A few local factors combine to keep Portland yards soggy:

• Clay soil. Much of Portland sits on dense clay that drains very slowly. Water can't infiltrate fast enough, so it ponds on the surface and the ground stays saturated for long stretches.
• The wet season. From October into spring, Portland gets sustained rain — and increasingly intense storms — that keeps loading the yard with water faster than clay can absorb it.
• Flat or poorly graded lots. Many older Portland properties were never graded for good drainage, leaving low spots and grades that send water toward the house instead of away.
• Roof and runoff water. Downspouts dumping near the house and runoff from neighboring higher ground add to the load.

Understanding which of these is driving your wet lawn is the key to fixing it — and it's why a generic French-drain-everywhere approach often disappoints in Portland clay.

Why Generic Advice Fails in Portland Clay

The usual internet advice — dig a deep gravel trench and the water will drain into it — assumes soil that lets water move. Portland clay doesn't. A deep French drain that relies on water seeping in from tight clay can sit nearly dry while the lawn above it stays wet, because the clay won't release its water.

What actually works in Portland clay is a surface-first approach: get water off the surface and carry it away, rather than waiting for it to soak down. That means grading, swales, and shallow collection feeding a real outlet — solutions matched to how clay behaves. It's the central reason local experience matters more than a one-size-fits-all fix.

Solutions That Work for Portland Yards

The right fix depends on the cause, and Portland yards usually need one or a combination of these:

• Regrading. Reshaping the yard to establish positive slope away from the house and toward an outlet fixes a large share of soggy-lawn problems, especially where the original grade is flat or wrong.
• Swales. A shallow, gently graded channel collects surface runoff and carries it to a safe outlet. Because it works at the surface, it sidesteps clay's infiltration problem entirely — often the highest-value move on a Portland lot.
• Area drains and catch basins. Placed at unavoidable low spots and tied to solid pipe, these capture water that grading alone can't reach and carry it to the outlet.
• French drains, used right. A shallow interceptor French drain can complement grading by catching surface and near-surface water; the parent yard drainage cost guide covers placement.
• Downspout routing. Getting roof water onto solid pipe and discharged well away from the house removes a major water source.

Most effective Portland yard fixes combine surface grading with targeted drains and a reliable outlet, rather than relying on a single buried trench.

The Outlet Question

Every yard drainage solution needs somewhere to send the water — the outfall — and on Portland's flatter east-side lots this is often the hardest part. A sloped West Hills lot usually has a downhill daylight point; a flat Southeast or North Portland lot may need a dry well to disperse water, a long run to reach a low point, or a permitted storm connection.

This is why two Portland yards with the same wet-lawn symptom can need very different solutions and cost very different amounts — the outlet options vary block to block. A drain with nowhere to send water just relocates the puddle, so identifying the outfall is central to any real fix.

What Drives the Cost

Yard drainage cost in Portland tracks the usual factors weighted by local conditions:

• Scope — how much of the yard needs work and how many drains
• Clay soil, which makes excavation slower and harder
• Site access — tight Portland lots, narrow side yards, mature trees, and fences can limit equipment
• The outlet — easy on a slope, more involved on a flat lot
• Restoration of lawn and landscaping after the work

Published ranges are industry baselines, not budget targets, and Portland projects often run higher because of clay and access. A site-specific quote is the reliable number.

Get Your Portland Yard Assessed

A soggy Portland lawn doesn't have to be a permanent feature of winter. The fix starts with diagnosing why your yard stays wet — clay, grade, runoff, or some combination — and matching the solution to Portland's conditions rather than generic advice. Surface-first grading and swales, targeted drains, and a real outlet are what dry out a Portland yard.

Our excavation services cover yard drainage designed for Portland clay and rain, from assessment through the outlet. Request a free assessment and we'll evaluate your lawn and recommend a lasting fix. Every Portland lot is different, so treat this as general guidance and get a site-specific quote.