Landslide Guide for Homeowners Released by State Geology Officials

PORTLAND, OR – It's been a wet winter and spring in the tri-county area, and with more rain still to come it might be wise for residents whose homes rest on or near hills to consider the potential for landslides.

County and city transportation officials in the Portland metro region dealt with more than 40 landslides this past winter leading into spring; so to mitigate the danger of anymore landslides, Oregon Department of Geology and Mineral Industries (DOGAMI) officials are advising homeowners to check out the recently released "Homeowner's Guide to Landslides" that could help to identify and reduce landslide hazards threatening homes and other property.

Made in partnership with the Washington State Department of Natural Resources, the guide provides tips for how to protect your home against possible landslides, what to look out for as potential risks, and what to do if a landslide occurs near your home.

"Mapping and studying landslides and other hazards is an essential first step in identifying practical ways to reduce risk to Oregon's people and communities," said State Geologist Brad Avy in a statement.

According to an interactive DOGAMI map of landslides in the region, Multnomah and Clackamas counties see more landslides than Washington County, with the largest concentration of landslide events occurring in Oregon City and the area north of Lake Oswego through Portland’s west hills to just north of Cedar Mill.

According to Multnomah County spokesman Mike Pullen, at one point during the winter every major route through the west hills had experienced some form of landslide.

"The hills around Portland can be unstable," Pullen told Patch Monday. "After 50 inches of rain (since Oct. 1, 2016), some roads just washed down the hill."

Particularly disastrous was the landslide that closed –– and continues to keep closed –– Northwest Newberry Road, which connects Highway 30 on the east to Northwest Skyline Boulevard on the west. As of late-April, the road is only open up to the slide area on either side so residents can still get to their homes, Pullen said, adding that Northwest Newberry Road typically sees roughly 1,500 trips per day.

An area prone to landslides, county officials had once planned to temporarily close parts of Cornelius Pass Road in order to repair and improve Northwest Newberry Road. But the last landslide was so severe county officials are now working to devise a new plan for repairing the roadway –– as well as a new plan to pay for those repairs.

"We're actively trying to get money for repairs," Pullen said. "It's like an extra $4 million in repairs that appeared overnight. We could take out a loan, but that's not a gift. We'd have to pay it back."

As the ground was unprepared to absorb so much water, so too was the county's budget unprepared to absorb the costs associated with subsequent emergency repairs.

Pullen said the county had considered moving Newberry Road about 100 yards to lessen the chances of another wipeout landslide, but nothing can be certain in an area that receives so much rain.

Homeowners on hillsides are obviously at the greatest risk, but any casual slope in the region –– with enough rainfall –– could become hazardous, according to the guide. A few warning signs to watch out for include tilted or bent trees, sagging or taut power lines, and sunken or broken road beds.

Interestingly, the guide suggests planting more trees and shrubs to soak up ground water as one way to reduce the risk of landslides on homes near hills, and to ensure all rainwater has proper draining outlets away from the base of the home and any nearby slopes.

For more information, check out the DOGAMI guide to landslides here.

This post was updated to include comments and information provided by Multnomah County spokesman Mike Pullen.

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