Excavation
Yard Drainage Cost Guide for Oregon Homeowners
Cojo
April 18, 2026
10 min read
Oregon's wet season is long, the soils west of the Cascades are clay-heavy, and most residential lots were graded for the footprint of the house rather than the movement of water. The result is a predictable pattern: soggy lawns, pooled water near foundations, downspouts dumping into dirt, and hillside runoff showing up in basements. Yard drainage is one of the most common excavation calls statewide.
The challenge for homeowners is that "yard drainage" is not one job. It is a family of solutions — French drains, dry wells, swales, surface drains, catch basins, channel drains, and regrading — and each one solves a different water problem. The right fix depends on where the water comes from, where it needs to go, and what your soil does along the way.
This guide is the umbrella view. It walks through the major drainage solutions used in Oregon, what each one typically costs, and how to pick the right approach before getting quotes.
Pricing varies widely because most yards combine two or three fixes. A simple downspout extension might run a few hundred dollars, while a full hillside interception system can run into five figures.
Industry Baseline Range
| Drainage Solution | Typical Scope | Industry Baseline |
|---|---|---|
| Downspout drain extension | 10 – 40 ft buried run | $400 – $3,500+ |
| Surface / area drain (single) | Low spot, grate, tie-in | $400 – $2,500+ |
| French drain (exterior) | Per linear foot | $15 – $120+ |
| Dry well (residential) | 250 – 1,000 gal | $1,500 – $10,000+ |
| Catch basin | Single basin install | $600 – $3,500+ |
| Channel drain | Per linear foot | $60 – $300+ |
| Swale excavation | Per linear foot | $8 – $40+ |
| Curtain drain (hillside) | Per linear foot | $20 – $90+ |
| Regrading / slope correction | Per sq ft | $0.75 – $4.00+ |
| Full-property drainage package | Whole-yard system | $6,000 – $40,000+ |
The industry baseline ranges above represent ideal conditions — easy access, workable soil, shallow depth, and minimal haul-off. In practice, actual project costs frequently exceed published averages by 2 to 3 times when complications arise. Oregon's clay soils, rocky terrain, unmarked utilities, permit requirements, and disposal fees can all push costs well above baseline figures. The excavation cost factors that drive any residential dig apply double here because drainage jobs are uniquely sensitive to soil and haul-off. The only reliable way to know your actual cost is through an on-site assessment.
Most small-scope drainage work carries a $500 – $1,500+ minimum job callout. A "just run a pipe from the downspout" job still costs the contractor crew time, fuel, locates, pipe, fittings, and haul-off.
Drainage jobs are uniquely prone to surprises because the water moving through your yard follows paths no one can see from the surface:
Simple downspout extensions and single surface drains are often half-day to full-day jobs. French drains, dry wells, and multi-drain systems typically run 2 to 5 days. Full-property drainage packages on clay-heavy hillside lots can run 1 to 3 weeks once permitting, material delivery, and landscape restoration are factored in.
Plan for 1 to 2 business days of lead time for 811 utility locates before digging begins.
You have standing water in a low spot in the lawn. Start with a surface drain or area drain tied into a dry well or daylighted outlet. If the whole lawn stays soggy, the real issue is usually clay soil plus grading, not one low spot — expect backyard regrading or a French drain to be part of the answer.
Water is pooling at the foundation. This is the one to fix fast. It typically takes a combination of downspout extensions, regrading the first 4 to 6 feet around the foundation, and sometimes a perimeter foundation drain.
A downspout is dumping water into a muddy spot. A downspout drain extension plus a dry well or daylighted outlet is usually the cheapest high-impact fix on the entire drainage menu.
Your driveway or garage takes on sheeting water. A channel drain across the driveway is the standard solution. Cheaper alternatives rarely hold up.
You get water coming downhill from uphill neighbors or forest. A curtain drain is the right tool. Trying to fix this with surface drains alone rarely works because the water is subsurface.
Your backyard holds water like a bathtub all winter. Usually a combination problem: clay soil + flat grade + no outlet. Expect a mix of regrading, a swale, and a dry well or outlet connection.
Willamette Valley clay. Clay soils absorb slowly, which means larger dry wells, wider French drain trenches, more gravel, and more haul-off. Expect clay sites to price at the middle to upper end of every range.
Rocky Central Oregon soils. Great natural drainage, but trenching through basalt and river cobble is slower and harder on equipment.
Coastal and river-valley sandy soils. Easiest to work with. Drainage is less urgent here, and when installed, systems tend to price at the lower end.
Wet-season scheduling. October through May is Oregon's wet window. Drainage work is still possible year-round, but wet-site conditions mean slower progress, more haul-off (wet clay spoils rarely get reused), and more landscape restoration.
Permit variance by jurisdiction. Portland, Eugene, Salem, Bend, and most incorporated cities treat stormwater management seriously. Full-property drainage systems that tie into the municipal storm system almost always require a permit.
DIY can handle:
Hire a pro for:
Most small drainage fixes do not require a permit. Permits typically come into play when you are connecting to a public storm drain, doing engineered foundation drainage, or altering grade significantly on a hillside lot. Budget $100 – $600+ for permit-related costs depending on jurisdiction.
Our guide on how to hire a residential excavation contractor goes deeper on interview questions, contract clauses, and red flags specific to Oregon drainage work.
Yard drainage is one of those problems that gets worse every wet season until it is solved. A dollar spent today on correct sizing is usually worth four or five spent reactively after foundation damage, mold, or landscape loss. Cojo provides on-site drainage assessments across Portland, Eugene, Salem, and the rest of the Willamette Valley.
Get a free excavation estimate, see our excavation services, or browse past projects. Additional drainage reading lives in our resources library.
How much does yard drainage cost in Oregon? Small fixes like a single downspout extension typically start around $400 to $1,500+. A French drain runs $15 to $120+ per linear foot, and a full-property drainage package — French drain, catch basins, dry well, regrading, and restoration — often lands between $6,000 and $40,000+ depending on lot size, soil, and slope. An on-site assessment is the only way to get a realistic number.
How long does a yard drainage project take? Simple jobs (one downspout, one surface drain) finish in a day. Most residential French drain or dry well installs take 2 to 5 days. Hillside or whole-property systems can run 1 to 3 weeks once permits, locates, and landscape restoration are included.
What is the cheapest yard drainage solution? A downspout extension to a daylighted outlet or small dry well is usually the cheapest high-impact fix. Regrading a shallow swale is also low-cost if the problem is truly a surface-water issue. The most expensive mistake is installing the wrong system for the real problem — fixing a subsurface water issue with a surface drain, or vice versa.
Does Oregon clay soil make yard drainage more expensive? Yes. Clay absorbs slowly and generates spoils that usually have to be hauled off rather than reused. French drains need wider trenches and more gravel, dry wells need more capacity, and haul-off loads add up fast. Expect clay-heavy lots to price at the middle to upper end of most ranges.
Do I need a permit for yard drainage in Oregon? Simple drains usually do not need permits. You generally need one if the drainage ties into the municipal storm sewer, if the work is engineered foundation drainage, or if you are changing grade significantly on a hillside. Check with your local building department before digging.
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