Landslides and flooding were the major problems as area rivers overflowed their banks and unstable hillsides collapsed.
Hardest hit by flooding were the Stillaguamish, Tolt, Skokomish and Dungeness rivers. The north fork of the Stillaguamish reached a record-high level of 15.3 feet, surpassing the previous record set in 1990.
At least six people were rescued by hovercraft near Granite Falls as raging floodwaters trapped them in their homes. Hundreds of homes were surrounded by floodwaters there and elsewhere in Western Washington.
Snohomish County Executive Aaron Reardon issued an emergency declaration Sunday evening to respond to flooding throughout the county, including an inspection of eroding banks along the Skykomish River near Index.
"We must protect public safety during these floods, and an emergency declaration enhances the efforts we already are making," Reardon said.
A voluntary evacuation was in effect for Granite Falls, and the Red Cross opened an emergency shelter there for displaced residents. A Red Cross emergency shelter was opened in Stanwood as well, where city officials said they are experiencing the worst flooding in the city's history.
Numerous highways were closed, including all of Highway 106 in Mason County and Highway 530 in Snohomish County between Interstate 5 and Arlington. Highway 16 in Kitsap County was closed for several hours, reopening at about 6 p.m.
In Kitsap County, Hunter Road washed out near Port Orchard, trapping more than 100 residents who live on the wrong side of the washout.
"I was awestruck because it had never happened before and I've been here 23 years," said George Peichoto, who lives nearby.
Those stuck on either side wonder what would happen if there were an emergency.
"If something was to happen, fire engines can't get through there. Ambulances can't get through there," said Tracy Cramer. "It's kind of disturbing for me."
All passenger and freight rail service was halted in Western Washington until Tuesday as slides covered the tracks in the Cascades and Clark County. Northline Sounder service between Everett and Seattle also was canceled for Monday and Tuesday morning and possibly longer.
The state Emergency Operations Center was activated as the rains kept falling, and county emergency operations centers were activated in Snohomish, Pierce and Skagit counties.
The hardest-hit area appeared to be along the Stillaguamish River, affecting Granite Falls, Oso and Marysville and other communities, where a severe flood warning was issued.
A voluntary evacuation request was made for about 230 homes and businesses along the Stillaguamish in Granite Falls as the river gushed at about four feet above flood stage late Sunday morning.
A rock slide covers Chuckanut Drive in Whatcom County.
Witnesses said logs were being carried on floodwaters through the yards of local residents as the river continued to rise.
Many other rivers were impacted as well, all across Western Washington, with flood warnings out for the Bogachiel, Skokomish, Satsop, Dungeness, Skykomish, Snohomish, Tolt, Snoqualmie, Puyallup, Newaukum and Chehalis rivers. A flood warning was issued for Issaquah Creek as well.
Water volume on the Tolt River in King County near Carnation was more than 2 1/2 times flood level.
Floodwaters cover yards and roadways in Granite Falls.
In Seattle, urban flooding was in issue in many areas of the city. In the Northgate neighborhood, at least a foot of water flooded an apartment building basement. Fire officials arrived and pumped water out as quickly as they could, and it was caught early enough that no water got into any of the cars parked in the building's garage.
Also in Seattle, a landslide alert was issued after more than 3 inches of rain fell in 24 hours, greatly increasing the chance of mudslides.
And in Burien, a landslide destroyed a home on SW 172nd Street, displacing a 94-year-old man who lived there.
Many roadways were covered in water from one end of the region to another.
Homes were reported flooded in parts of Mason County. Basement flooding was widespread all across Western Washington.
Other trouble spots included these:
• Amtrak rail service was cancelled until Tuesday between Seattle and Portland and also between Seattle and Spokane due to mudslides over the tracks.
Floodwaters surround homes along the Stillaguamish River near Arlington.
• Northline Sounder service between Everett and Seattle was canceled on Monday and Tuesday morning - and possibly longer - due to mudslides. A backup bus service will be available.
• Heavy rains combined with a computer malfunction caused a sewer overflow in Medina. Officials said it is unclear how much sewage spilled.
• About 3,400 homes lost power Sunday morning in Seattle, with the largest outage affecting about 2,900 customers in the Skyway area of southeast Seattle. A large outage also was reported in Grays Harbor County.
• Both directions of Highway 16, the main route between Tacoma and northwestern Washington, is closed due to flooding over the roadway at Gorst.
• Meadowbrook Park in Lake City was closed after stormwater overwhelmed the park's pump station and flooded the park with sewage. The force of the stormwater blew open a concrete block on a sediment trap.
• The entire length of Highway 106 in Mason County is closed due to flooding and several mudslides.
• Chuckanut Drive in Whatcom County remains closed by a rock slide.
• Mudslides were reported along the length of Highway 302 in Mason County.
The U.S. Army Corps of Engineers has deployed six flood fight teams for the potential of conducting emergency operations as rivers begin to rise across Western Washington.
The Corps has sent flood teams out to the Olympic Peninsula, and the Chehalis, Nooksack, Skagit, Snohomish and Puyallup River basins.