Flood Risk Around Portland: Johnson Creek, the Willamette and the Columbia Levees

What flood history does the Portland area have?

The benchmark is February 1996, when the Willamette crested at 28.6 feet in Portland, a few inches short of overtopping the sandbagged downtown seawall, and at 46.04 feet at Oregon City. The Columbia crested at 27.2 feet at Vancouver, damaging nearly 300 Clark County homes. Smaller creek floods recur.

The Willamette in 1996 came within a few inches of the top of the downtown seawall, which crews sandbagged. Farther upstream, the river gauge below Willamette Falls reached 46.04 feet on February 9. On the Columbia, Clark County Public Works records a crest of 27.2 feet at Vancouver on February 9, against a flood stage of 16 feet, with nearly 300 homes damaged and 82 destroyed.

Creeks tell a different story. Fanno Creek recorded a gauge peak of 733 cubic feet per second on February 8, 1996, and a school near the creek reported its worst flooding in January 2017. Johnson Creek reached about 15.3 feet in 2015, according to a local television news report.

The benchmark matters less for its exact numbers than for what it shows: the metro area has seen the Willamette come within inches of the seawall, creeks surge in hours and the Columbia rise well above flood stage, all in the same winter season. None of that guarantees a repeat, and none of it is rare enough to ignore.

What is Johnson Creek and who is at risk?

Johnson Creek is a 26-mile stream draining roughly 54 square miles across Clackamas and Multnomah counties, through Gresham, Happy Valley, Portland and Milwaukie, where it meets the Willamette. It has a flood history. Creekside lots and low riverside streets are the concern, according to the city's Bureau of Environmental Services.

A restoration project in Gresham reconnects the creek to its floodplain, and local flooding has been reported as better in recent years, according to the Bureau of Environmental Services and local news. Better does not mean gone, and a home beside the channel should still ask about flood cover.

The creek's watershed reaches into Happy Valley, and its headwaters are in Clackamas County near Damascus. Rain on the upper watershed shows up downstream within hours, which is why creek floods rise fast.

Milwaukie sits where the creek meets the Willamette, and low riverside lots there are the ones that owners ask about. The February 1996 Willamette flood affected this stretch of river, according to the National Weather Service.

If you live near the creek, the practical questions are the same as anywhere: where is the lowest opening in your house, what is stored below the flood line, and does your policy treat creek water as flood.

What is the story with the Columbia levees?

A levee system about 27 miles long runs from North Portland through Gresham, Fairview and Troutdale. Landowners built it from 1917 to 1921, and the Army Corps later improved it. According to Multnomah County, its FEMA certification has expired and accreditation could be revoked. We could not confirm its current status.

Drainage districts operate the levees. County materials and legislative testimony from 2019 to 2023 describe the recertification question. A lapse can change flood map status and insurance requirements for properties behind the levee.

The practical step is to check your own address against the current FEMA flood map, ask the county or your insurer what the status means for you and not assume you are safe or at risk. Fairview and Troutdale sit inside this system, as do parts of Gresham.

Troutdale sits at the east end of the system, where the Sandy River meets the Columbia. Fairview, between Portland and Gresham, sits inside it. A levee reduces risk on one side but does not remove it, and a lapse in certification is a question about maps and insurance as much as about the structure.

When does the Portland area tend to flood?

Mostly from November through February, when downtown averages 4.74 to 7.35 inches of rain a month by the 1991 to 2020 normals and ground is saturated. The 1996 flood came in February. Summer is dry, with July averaging 0.43 inches. Any single year can vary widely, and this is a tendency, not a forecast.

Floods here come from the combination of heavy rain on saturated ground and, for the big rivers, rain falling across large watersheds. We have no sourced figures on snowmelt contributions, so we make no claim about them.

The table sets the rain normals against what has been reported.

Atmospheric rivers, the long bands of warm, moist air that bring days of steady rain, are the type of storm most associated with winter flooding in the Pacific Northwest. A March 2026 atmospheric river closed roads in Portland, a reminder that storms are not confined to midwinter.

Does homeowners insurance cover flood?

Usually not. Oregon's Division of Financial Regulation notes that flood is a standard exclusion in homeowners policies, so flood cover is generally a separate policy, such as one through the National Flood Insurance Program. Only your insurer can say what yours does. Such policies often have a waiting period, so ask before the wet season.

People tend to learn the gap after the event. A burst pipe and a rising creek can put water in the same basement, and the policy treats them differently. Ask your agent which causes are covered.

Flood cover decisions are easier when made in summer. You cannot buy it in the middle of a storm and expect it to respond to that storm.

Sewer and drain backup is a separate question, and is often covered only by an endorsement. A flood that also overwhelms the sewer can raise both questions at once, so a clear record of how the water entered is valuable.

What does flood cleanup involve?

The crew treats the water as contaminated, pumps in stages, shovels out silt, removes carpet, pad, wet drywall and insulation, washes and disinfects hard surfaces and dries the structure to readings. Furnaces, water heaters and panels that took in water need a qualified inspection before use.

Pumping a flooded basement too quickly can stress walls and floors against saturated soil, so the water is lowered gradually.

Photographs of the high-water line, a list of what was removed and the moisture log support any claim. See flood damage cleanup for the service in detail.

Items that sat in flood water are usually discarded, and the list can be long: carpet, pad, upholstered furniture, mattresses, cardboard and particleboard. Photograph each item before it goes and keep a rough inventory.

The slow part is rarely the pumping. It is the silt, the removal of everything porous, and the time for concrete and framing to dry. A basement that took a few feet of water can need a week or more before rebuilding can begin, and a technician decides from readings, not from the calendar.

How do you check your own risk?

Look up your address on the current FEMA flood map, ask your county or city about local flood history, ask your insurer what applies and find out whether your property sits behind the Columbia levees or beside a creek. A map is a starting point. Past floods have also reached places the map did not show.

Neighbors who have lived in the area for years are a useful source on where water has gone. So is a property disclosure, if you are buying.

If you are near a creek or river, keep valuables off the floor in the lowest level, know where the main shutoff and electrical panel are, and have a plan for leaving.

If you are buying, ask the seller about water history and ask the insurer for a quote on flood cover before closing. The premium and the terms are part of the cost of owning the house. A flood policy that the seller did not need is still something you may need.

What about Vancouver and Camas?

They are in Clark County, Washington, on the north bank of the Columbia, so the Columbia flood history applies directly to their low riverside land. Washington contractors register with the Department of Labor & Industries rather than Oregon's CCB, so the license check differs. The restoration work itself is the same.

Clark County Public Works records the 1996 crest at Vancouver of 27.2 feet and an earlier crest of 33.6 feet in 1894. We have no Camas-specific flood figures, so we cite none.

Insurance rules and agencies differ in Washington. Ask a Washington agent about flood cover for a Washington address.

If you commute across the Columbia or own property on both sides, remember that each side has its own agencies, contractor rules and, often, its own insurance agent. A policy written for an Oregon address does not automatically cover a Washington one.