Storm turns roads into rivers, flood watch in effect

(UPDATED: 6 a.m. Tuesday, Dec. 8)

WHEATLAND - The Wheatland Ferry is closed due to high water.

. . . McMINNVILLE -- Highway 99W at the St. Joseph overpass is open again, after being closed most of the day Monday. Traffic is flowing as normal.

. . . GRAND RONDE - Highway 22 is closed Northwest of Grand Ronde, about 2.5 miles east of Dolph Junction in Yamhill County due to erosion beneath the road surface.

A sinkhole has developed that reaches into both lanes of the highway.

This will be a long-term closure as the road must be rebuilt.

Local traffic can access points on either side of the closure, but through traffic must use Highway 18 as an alternate route.

. . . The South Yamhill River at McMinnville has risen to more than 40 feet, according to the National Weather Service Advanced Hydrologic Prediction Service.

Flood stage is 50 feet. The highest crest, 59.33 feet, was recorded in 1996.

The South Yamhill at Willamina was measured at 14.72 feet Monday. The highest projected level in the coming days is 14.15 feet.

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(UPDATED: 9 p.m. Monday, Dec. 7)

A Pacific Northwest storm system that ramped up overnight flooded streets and roads in urban and rural parts of the entire Yamhill Valley on Monday, leading to closure of Highway 18 at its intersection with Highway 99W at the south end of McMinnville and both lanes of Highway 99W at the St. Joseph overpass between McMinnville and Lafayette,

Also awash in water were Abbey Road north of Lafayette, the Bellevue Highway between Bellevue and Amity, and Highway 99W through Dundee, which was virtually impassable. That’s not to mention numerous roads west of the Yamhill-Carlton area, which had to be closed outright.

“We’ve got water reaching just about every road we own,” Yamhill County Public Works Director John Phelan said early Monday afternoon. “There’s hardly a road in the county that does not have a flooding problem right now.

“During the past six weeks, we have emphasized cleaning ditches and making sure things are up to par. But when it rains for four or five solid hours, you unplug one culvert and it’s too much for another one down the line.”

Phelan said creeks throughout the county are at capacity. “Baker Creek can’t hold any more water,” he said, citing one of the worst.

The Amity, Dayton, Gaston, McMinnville, Willamina and Yamhill-Carlton school districts all released students early Monday, and canceled after-school activities. Sheridan kept students all day, but canceled after-school activities.

Sandbag filling stations were opened in McMinnville and Sheridan, in response to a flood watch issued by the National Weather Service.

The flood watch is slated to remain in effect through Wednesday afternoon. It means there is a potential for flooding, based on current forecasts.

However, the situation looked good in Sheridan, one of the most flood-prone spots in the entire valley, on Monday.

“The river is below normal for what we expected,” Sheridan City Manager Frank Sheridan said of the South Yamhill, which flows through the heart of the city’s low-lying downtown. “It is higher in different spots than I’m used to seeing, but it’s still not a problem.”

McMinnville Public Works Director David Renshaw said he was happy to see blue sky and a bright sun early Monday afternoon, when the storm finally began to ebb.

“The crews have been very busy responding to reports of high water and flooded intersections and streets in all four quadrants of the city,” he said. “And that work is ongoing.

“Our biggest concern is a storm drain capacity issue. There’s more water than the system can handle. The system just has to catch up.”

Renshaw said it’s fortunate the storm arrived at the end of the city’s leaf season. “Leaves were not down on the streets, blocking the catch basins,” he said — at least not for the most part.

As area rivers, streams and streets continue to flood, motorists are advised to not attempt to drive through high water, which can lead to stalling or worse. Vehicles can even become entrapped and swept away.

With water washing over the road, a woman became trapped on top of her vehicle on Moores Valley Road, west of Yamhill. She had to be rescued by a Yamhill police officer.

The deluge emanated from the first in a series of Pacific frontal systems moving this way, according to the National Weather Service. It rolled into Northwestern Oregon on Sunday night.

A second system arrived Monday, and additional systems were expected today, Wednesday and Wednesday night.

One location in the North Oregon Coast Range got 4 1/2 inches of rain in 24 hours Sunday night and Monday morning. The forecast called for 4 to 5 inches in the Willamette Valley and up to 12 inches the flanking Coast and Cascade ranges.

Falling on already saturated soil, heavy rain promises to swell rivers throughout the western part of the state. Several river systems have the potential to reach flood stage.

The South Yamhill at McMinnville is expected to rise to 52.22 feet between 9 a.m. today and 9 a.m. Wednesday. That’s 2.22 feet over flood stage.

Other Willamette Valley rivers at risk of overflowing their banks include the Alsea, Clackamas, Luckiamute, Pudding, Siletz, Trask, Upper Tualatin and Wilson, plus Portland’s perennially flood-prone Johnson Creek.

Landslides and debris flows are also possible.

“Intense rainfall is a common landslide trigger,” said Bill Burns, engineering geologist at the Oregon Department of Geology and Mineral Industries. “Landslides and debris flows are possible during this period of severe weather, so it’s important to be aware of the potential hazard.”

Debris flows are rapidly moving and extremely destructive landslides that can easily travel a mile or more, depending on the terrain. They are capable of transporting boulders and logs in a fast-moving soil and water slurry.

People, structures and roads located below steep slopes in or near canyons face the greatest risk. Caution should be exercised when traveling.

According to DOGAMI, the most dangerous places include:

n Canyon bottoms, stream channels and areas of rock and soil accumulation at canyon outlets.

n The bases of steep hillsides.

n Road cuts or other areas where slopes of hills have been excavated or over-steepened.

n Places where slides or debris flows have occurred in the past.