Home Service areasCooper Mountain

Tree service on Cooper Mountain and in southwest Beaverton

Cooper Mountain rises to nearly 800 feet on Beaverton's southwest edge. It holds three kinds of property at once: acreage homes on the ridge that have been there for fifty years, 1990s subdivisions on the east slope, and the new streets of South Cooper Mountain near Mountainside High School.

Call (503) 386-0199 Request an estimate

Harry Fauver, founder. Updated September 2026.

Where Cooper Mountain sits.

Pick any other dot to open that area.

The trees of Cooper Mountain

ZIP 97007. Part inside Beaverton, part unincorporated Washington County, along 175th Avenue, Kemmer Road and Scholls Ferry Road.

The mountain is an old volcano, and its soil is a thin layer of clay over basalt. That, more than anything, shapes its trees. It is also one of the few places in the area where Oregon white oak woodland survives, which you can see in the nature park at the top.

Oregon white oak is the signature tree. Oaks here can be two or three centuries old, and they resent change: soil piled over their roots, lawn irrigation under their canopy, and trenching all kill them slowly. Good oak care is mostly about what happens on the ground around them, plus careful removal of deadwood.

Douglas-firs on the ridge root into shallow soil over rock and take the full force of south and east winds. They are generally well adapted, but firs left alone at the edge of a newly cleared lot are exposed in a way they never were before, and they deserve a look in the first few winters.

In the new subdivisions the trees are of two kinds: young street trees that need structural pruning in their first ten years, and preserved groves fenced off during construction. Grading and utility trenches near those groves often cut roots, and the damage shows up as dieback a few years after the houses are sold.

What we are usually called for on Cooper Mountain

Oak deadwood and clearance

Conservative pruning of mature Oregon white oaks: dead limbs out, clearance over the roof and the driveway, and nothing more than the tree can afford to lose. Tree trimming and maintenance.

Exposed firs on the ridge

Inspection and, where needed, removal of firs that have started to lean or lost their top since the lot next door was cleared. Tree removal.

Storm damage on acreage

Long driveways blocked by fallen trees, and limbs on the fences and outbuildings of larger lots along Kemmer and Grabhorn roads. Emergency tree service.

Clearing stumps for building

Old orchard and fir stumps on lots being built or landscaped. Anything under a footing, a slab or a wall comes out whole and the hole is compacted. Stump removal.

Around Cooper Mountain

Local landmarks, and what the trees around each one tell you about your own.

Cooper Mountain Nature Park

The park protects oak woodland and prairie on the south slope, with views to the Chehalem Mountains. It is the best local example of what a healthy Oregon white oak looks like: a wide, open crown over ground that is never watered, dug or paved.

Mountainside High School and South Cooper Mountain

The newest part of Beaverton. Street trees here are a few years old, which is exactly when a few small cuts set good structure for life. The fenced groves between the houses are protected as a condition of the development.

175th Avenue

The steep, narrow road over the mountain is lined with tall firs on both sides. Trees along it belong to the adjoining owners, and work beside the road needs traffic control and, in the county stretches, a right-of-way permit.

Kemmer Road and the ridge

Larger lots, many of them still outside the city. Wells, septic systems and drain fields are common up here, and each has to be located before a stump is ground or dug.

Cooper Mountain and Neighbors Southwest on the map. Open in Google Maps

Which tree rules apply on Cooper Mountain

Cooper Mountain is split. The newer subdivisions have been annexed into Beaverton, while much of the ridge is still unincorporated. Find out which side you are on before anything else.

Inside Beaverton city limits

The tree between the sidewalk and the street is a street tree. You maintain it, and removing it takes a city permit and normally a replacement from the city's approved list. Cutting 20 percent or more of the crown or roots counts as removal. Street trees have to clear 8 feet over the sidewalk, 12 feet over the street and 14 feet over arterials, and topping them is prohibited.

Most ordinary backyard trees need no permit. The exceptions are the trees the development code protects: significant and historic trees, trees in significant groves and natural resource areas, and landscape or mitigation trees that were kept or planted as a condition of the subdivision. If your lot backs onto a greenway, a creek or a preserved grove, treat the trees along that edge as protected until the Planning Division (503-526-2420) says otherwise.

In unincorporated Washington County

No city tree code applies here, even with a Beaverton or Portland mailing address. The county generally leaves trees on a developed home lot to the owner, with two big exceptions: mapped Significant Natural Resource areas, and the vegetated corridors along creeks and wetlands that Clean Water Services regulates. Cutting inside either can need review, even for a dead tree.

Trees along the road are generally the adjoining owner's responsibility, and a county right-of-way permit is needed when planting or removal affects traffic. Many subdivisions add a layer of their own, with covenants and common-area trees that need the homeowners association's approval. For neighbor disagreements over trees, the county points residents to free community mediation.

Specific to Cooper Mountain

The new subdivisions were approved with tree protection plans, so their preserved groves and required plantings are protected for the long term. On the county side, the mountain's upland habitat is mapped as a natural resource in places. Septic systems are common on the ridge, which matters for stump work.

The permit checker gives a first answer in two questions, and the permit guide has the detail. We check every tree's status before a job is booked.

Tree services we offer on Cooper Mountain

How a job goes

You call or send the form and tell us what the tree is doing. Phone photos help.
We walk the site and write the estimate in plain language.
Permits and the 811 utility locate are sorted out before any saw starts.
On the day, drop zones are protected and anything over a structure is roped down.
We rake, blow and haul, then walk the yard with you before we leave.

Nearby areas we also serve

Tree service questions from Cooper Mountain

Are Oregon white oaks protected on Cooper Mountain?

It depends on the lot. Inside the city, oaks in preserved groves, natural resource areas or an approved landscape plan are protected. On county land the question is whether the tree is in a mapped natural resource area. We check before booking.

Why is my old oak dying back after we landscaped?

Oregon white oaks are adapted to dry summers and undisturbed soil. Irrigation under the canopy, added soil over the roots and trenching are the usual causes of decline. Stopping the watering and keeping the root zone clear helps more than any pruning.

Am I in Beaverton or in Washington County?

On Cooper Mountain the boundary follows annexations lot by lot. Your property tax statement shows whether the City of Beaverton is one of your taxing districts. It decides which tree rules apply to your street trees.

The builder left a grove behind my new house. Can I thin it?

Probably not without approval. Groves kept during development are normally protected as a condition of the subdivision, and some belong to the HOA. Dead and hazardous trees can usually be dealt with, after the right approval.

Do you give free estimates on Cooper Mountain?

Yes. We walk the site, tell you what the tree needs, and put the scope in writing: what is cut, how it comes down, where the wood and chips go and whether the stump is included. Call (503) 386-0199 or send the form on this page.

Request an estimate

Tell us about the tree and we'll call to set up a site walk. For emergency service, skip the form and call.