Flood — Umatilla, Oregon

2020-02-06 to 2020-02-08 · near Milton Freewater, Umatilla, Oregon

Event narrative

Umatilla County ' There was record flooding along the entire reach of the Umatilla River. There was extensive damage to areas along the river, including homes, roads including Interstate 84, railroads as well as other public facilities such as parks and sports complexes. Along the upper reaches of the river, roads were washed out with homes damaged or destroyed. One resident was swept away by flood waters and died. A number of residents had to be evacuated via helicopter or 4 wheeler with 70 homes on the Umatilla Indian Reservation damaged. The Riverview Mobile Home Park at Pendleton was inundated. There was minimal to no damage through Pendleton, due to the levee, but the Bob White Baseball field had extensive damage as water overtopped a low wall. Adjacent to Pendleton, the levee was damaged and overtopped with water flowing through the Keystone RV Manufacturing plant and the Colby Pipe Company. Several bridges and roads downstream from Reith to Echo were damaged or washed out with a number of homes damaged. Downstream from Echo to the confluence of Columbia River, the river rose out of the banks and flooded Interstate 84 between Highway 395 and Highway 208. Several semi-trucks were stranded in the flood waters with extensive damage to the highway. Numerous pastures and buildings along the river through Stanfield were flooded with extensive damage to Oxbow Park in Hermiston and to a sports complex in Umatilla. There was extensive flooding as well as on the Walla Walla River from the headwaters through Milton Freewater and on the upper reaches of Mill Creek. Numerous levees along the Umatilla and Walla Walla Rivers were damaged or overtopped including near Milton Freewater, several locations on the Umatilla Indian Reservation and adjacent to Pendleton. Damage is estimated at 1.3 million dollars to private property on the Umatilla Indian Reservation, with damage for public infrastructure for the entire county at 39.7 million dollars.

Umatilla at Pendleton ' Flood stage is 12.3 feet. The river rose above flood stage on February 6th 1230 pm, crested at 19.18 feet on February 6th at 10 pm, then fell below flood stage on February 8th at 11am. This was a record peak flow of 19,400 cfs. Highway 11(major access way to Pendleton) was closed due to water flowing over the road. Several bridges and roads downstream from Reith to Echo were damaged or washed out with a number of homes damaged. Umatilla near Gibbon ' Flood Stage is 7.0 feet. The river rose above flood stage on February 6th, at 2 am, crested at 12.14 feet on February 6th, at 130 pm, then fell below flood stage on February 8th at 645 pm. This was a record peak flow of 13,900 cfs. There was extensive damage along the upstream portions of the river with over 70 homes damaged, roads and railroad tracks washed out, levee damaged or washed out.

Wider weather episode

Summary : Heavy snow on February 4-5, 2020 was followed by a period of heavy rain, February 5-7. Snow levels rose to near 5000 feet. The heavy rain and snow melt lead to moderate flooding and several landslides along the East Slopes of the Washington Cascades. There was record flooding on several rivers, including the Umatilla, Walla Walla and Touchet rivers with widespread flooding of numerous other creeks and streams and rivers across Umatilla, Union and Wallowa Counties of Oregon and Walla Walla and Columbia Counties of Washington. Initial Weather Conditions February 1, 2020, snowpack across along the East Slopes of the Washington Cascades ranged from 80 to 100 percent of normal. Across the northern Blue Mountains of Oregon and northern Blue mountains of Washington the snowpack was near normal. A weather system brought heavy snow to this region on February 4th and the first part of the day on February 5th with snow amounts from around 10 to 20 inches for locations between 2000 to 4000 feet. During the afternoon of the 5th, snow changed to rain at elevations below 5000 feet. Selected locations snow amounts for February 4-5, include 8 inches at 2.6 miles SSE of Snoqualmie Pass, 7 inches at Cle Elum, 2 inches at Easton, 12.5 inches at Ski Blue Wood and 2 inches at Dayton in Columbia County. For Oregon, snow amounts include, La Grande 7-10 inches, Summerville 10 inches, La Grande, 5 Miles NNE- 17.5 inches, Meacham 13 inches, Elgin 9.8 N 8 inches, Joseph 6 inches and Wallowa 8 inches. The rain continued over through February 6 and 7th. Precipitation amounts in the form of rain at the headwaters of the rivers, ranged from 3 to 5 inches. Rain amounts for the 48 hours ending on the morning of February 8th, for selected locations include 6.31 inches at 2.6 miles SSE of Snoqualmie Pass, 3.27 inches at Easton, 5.83 inches near Lake Cle Elum and 2.17 inches at 8.7 miles NE Dayton. Snotel sites reported 2 day precipitation amounts of 6.3 inches at Touchet #2 in the Columbia County. There was 1.98 inches over 72 hours at 1.1 NE Walla Walla. In Oregon, rain amounts for the 48 hours ending on the morning of February 8th for selected locations include: from Coop Observer, Emigrant Springs ' 2.82 inches, Union 1.01 inches , Cove- 2.48 inches, La Grande - 2.50 inches, Lostine ' 1.39 inches. From CoCoRahs and other public weather spotters, 9.8 N Elgin ' 5.45 inches, La Grande- 3.02 inches and Wallowa 2.66 inches. Snotel sites reported 2 day precipitation amounts of 5.9 inches at High Ridge, 3.0 inches at Moss Springs, 1.6 inches at Milkshake. In addition, the snowpack from the preceding day was melted, contributing to the runoff. Observations show 5 to 7 inches of snow melted from February 5th to February 6th at Easton and Cle Elum. Home owners in the Lake Cle Elum area noted a loss of 3 to 5 feet of snow An observer located 5 miles north of La Grande reported 17.5 inches of snow fell on February 4-5 and then by the morning of February 6th, the snow depth had decreased to around 8 inches and was depleted during the day on the 6th. Satellite snowpack images show 1-3 inches of snow water equivalent (or water held in the snowpack) melted out along both the east and west sides of the northern Blue Mountains in Oregon and around the foothills of the Grande Ronde Valley generally between 2000 to 4000 feet. Streams, creeks and rivers rose rapidly through the night of February 5th, with the first instance of flooding reported on early morning on February 6th. The streams and rivers continued the rapid rises through the day on February 6th, with the Umatilla River reaching record high water levels at the gaging sites near Gibbon and at Pendleton and moderate flooding on the Grande Ronde River at the gaging sites near Perry and Troy. Most rivers and streams crested overnight on February 6th or on the morning of February 7th and then slowly receded back below flood stage on February 8th and 9th.

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Source: NOAA Storm Events Database, event_id 871967. Narrative written by the NWS forecast office that issued the report.