As crews work to open roadways swamped by mudslides in the wake of the powerful "Pineapple Express" that roared through Western Washington over the weekend, officials warn that more damage could come from saturated slopes.

The storm dumped nearly a foot of rain on the Olympic Peninsula and several inches across much of the Puget Sound area, flooding rivers, swamping basements and spilling sewage.

Authorities may need several days or longer to open some of the damaged roads.

Snohomish County was among the hardest-hit areas, with dozens of homes damaged in Granite Falls, Arlington and Stanwood when the Stillaguamish River reached record levels.

A mudslide over train tracks halted Sound Transit rail travel between Seattle and Everett — passengers were rerouted onto buses — and another slide north of Vancouver, Wash., halted Amtrak service between Portland and Vancouver, B.C. Amtrak trains bound for Vancouver, B.C., and Spokane will not run Tuesday, Amtrak officials said, but buses will be provided. Trains headed south to Portland, Eugene and Los Angeles were to resume Tuesday.

Most of the damage was from landslides and flooding in low-lying rural areas. State geologist Isabelle Sarikhan said about 20 landslides were reported in Western Washington but dozens more probably occurred in the mountains.

No deaths or serious injuries have been reported.

Mercifully, the rain let up Monday morning and afternoon before some showers returned in the evening. Forecasters said the typical Northwest rain mixed with showers expected over the next few days shouldn't raise river levels significantly. Snow was expected in the Cascades on Monday night.

But additional mudslides are possible; many slopes are saturated and can't hold any more moisture, according to the state Department of Natural Resources.

And crews have their hands full dealing with problems from the weekend.

Some flooded roadways may reopen as soon as the floodwaters recede, but in other areas it will be longer.

"We have to make sure the slope is stable before they can start clearing the roadway," said Rochelle Ogershok of the King County Transportation Department. "Once you get the debris cleared, you have to inspect" to see if the road is damaged.

Some spots that presented particular challenges for King County crews Monday:

• A mudslide on Northeast 117th Place in Kirkland;

• A section of road that slid along West Snoqualmie Valley Road between Carnation and Duvall;

• Damage to a retaining wall along Rainier Avenue South near Renton;

• Slides along Dockton Road and Gorsuch Road on Vashon Island.

The storm, from midday Saturday to about 7 p.m. Sunday, dumped 11.5 inches of rain at a weather station near Lake Quinault on the Olympic Peninsula.

National Weather Service meteorologist Johnny Burg said Seattle-Tacoma International Airport has recorded nearly 10 inches more rain than average this year, and 2010 might make the list of top 10 wettest. He said Sea-Tac usually receives about 34 inches a year, but nearly 44 had fallen as of Monday evening.

During the weekend, more than 5.5 inches of rain fell in Bremerton and Shelton, and 3.6 inches fell at SeaTac.

Flood warnings remained in effect Monday evening for eight area rivers — the Skykomish, Snohomish, Snoqualmie, Chehalis, Skokomish, Nooksack, Skagit and Stillaguamish.

In Seattle, crews were working to clear mudslides, including one on the Burke-Gilman Trail.

Lake City residents Allan and Signe Tencer, who live just below the trail, were awakened by the sound of the slide at 5 a.m. Out their window, they saw mud, trees and downed power lines just beyond their front door.

A power pole had crashed onto their garage, dropping a transformer through the roof. Police told them to stay inside to avoid the potential danger of downed, live power lines.

The couple's cars were stuck for hours.

"We're not trapped," Allan Tencer quipped. "We have bikes."

The rainfall at several places — including West Seattle, Green Lake and South Park — was close to that of a 100-year storm, according to Seattle Public Utilities. Most of the city received rainfall similar to a 20- to 30-year storm.

Overflowing sewage closed two Seattle parks, Carkeek and Meadowbrook. As of Monday evening, Carkeek Park's Salmon to Sound Trail remained closed, according to parks spokeswoman Joelle Hammerstad.

In Medina, sewage flowed into Lake Washington most of the day Sunday because of a pump failure.

In Kitsap County near Port Orchard, about 200 homes were isolated when a large chunk of the only road into a remote rural area collapsed Sunday. A logging road in and out of the area was swamped and impassable Monday morning.

Ruth Schaefer, a veteran King County levee inspector on the Green River, told two less experienced workers how lucky they were to be looking for damage in benign weather Monday.

"It was warm, sunny, no wind. I was telling these guys it's never going to get better than this," said Schaefer, who led the team checking potential trouble areas between Auburn and Tukwila.

They kept their eye on some logjams but didn't find any indication of structural problems with the levees.

Inspectors from the county, Army Corps of Engineers and four cities along the river were keeping close watch.

Seattle Times reporters Susan Gilmore and Keith Ervin and The Associated Press contributed to this report.

Jack Broom: 206-464-2222 or jbroom@seattletimes.com

In Kitsap County near Port Orchard, about 200 homes were isolated when a large chunk of the only road into the remote rural area collapsed atop a culvert Sunday afternoon. A logging road that had allowed some vehicles in and out of the area was swamped and impassable Monday morning.

Although showers return to the forecast by Monday evening, they are not expected to cause further flooding, according to the Weather Service. Snow is expected in the Cascades on Monday night. The typical Northwest weather pattern of rain mixed with showers will take hold the rest of the week.

Sewage flowed into Lake Washington most of the day Sunday because of a pump failure in Medina. Elsewhere, overflowing sewage flooded a yard in Mercer Island and closed two Seattle parks, said Annie Kolb-Nelson, spokeswoman for the King County Department of Natural Resources and Parks.

"During very severe weather, the conditions in the system can cause it to be overwhelmed," Kolb-Nelson said.

Seattle is especially prone to overflow problems, she said, because of old pipes.

Sewage began to overflow at the Medina Pump Station about 1 a.m. Sunday, and a computer malfunction then made the problem worse, according to a county news release. Crews began using manual pumps, but an unknown, "significant" amount of sewage continued to flow from the station directly into Lake Washington on Sunday afternoon, Kolb-Nelson said.

Meanwhile, the Cascade Siphon in Renton was backed up and sewage was overflowing into the Cedar River, and the Carkeek, Hidden Lake and Richmond Beach pump stations reported overflows into Puget Sound.

Seattle closed Meadowbrook Park in North Seattle after an overtaxed sewer line blew open a concrete block over a sediment trap, causing wastewater to spill into the park. Crews also closed Carkeek Park after a volunteer reported sewage washing across a trail Sunday afternoon.

On Mercer Island, an overtopped manhole sent sewage streaming into a yard, so the county called in cleaning crews.

In several King County neighborhoods, homeowners watched as floodwaters inched closely toward their homes.

In the Haller Lake neighborhood, Aivia Monitto and her boyfriend, Derek Thirstrup, spent the bulk of the day running two industrial pumps to keep water from flowing into the first floor of their split-level home.

The couple, who live in the 300 block of Northeast 125th Street, said they were among five homes near Haller Lake trying to keep floodwaters from Northacres Park from seeping inside.

Monitto said this is a replay of what happened to their home Dec. 3, 2007. A deluge flooded their yard, and mold developed in the ground level of their home, which has kept them from using the area for anything but storage.

In Kenmore, Frankie Schmitt found herself battling the worst floodwaters she has seen in 27 years.

She rented an extra sump pump Friday and asked the Kenmore Fire Department to bring out sandbags to help protect her property. But she said the water in her driveway Sunday was 4 feet deep and that the garage from which she runs her machine-quilting shop was taking on water.

Nearby Swamp Creek floods often, and changes the city made recently to the street seemed to make it worse, she said. Beaver dams cause the high water to back up on her side of the creek, she said.

In a North Seattle neighborhood, residents strategically placed sandbags around their homes, said Ryan Steffens, who has lived in the neighborhood close to Northgate for six years. Steffens said water gushed from a manhole cover in the middle of the intersection at North 107th Street and Midvale Avenue North until around noon, when the rains lightened up.

Jack Broom: 206-464-2222 or jbroom@seattletimes.com