SEATTLE — A state review of logging near the deadly March landslide in Oso has found that a timber company logged one acre more than was allowed under a 2004 permit, but the report was inconclusive on whether logging strayed into a more restrictive or potentially unstable area.
The Department of Natural Resources released its review on Tuesday, nine months after the deadliest landslide in U.S. history killed 43 people about 60 miles northeast of Seattle.
In the aftermath of the disaster, questions were raised about logging in a 7-acre area at the top of the slope nearly a decade earlier.
The review did not look into the cause of the March 22 landslide. It focused instead on regulations and decisions over the past decade to grant applications for logging within a mile of the landslide area.
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“The SR 530 landslide was a terrible tragedy, and we want to understand the history of timber harvests in the area,” said state Forester Aaron Everett. He said the agency would evaluate the results as part of its efforts to increase protection on unstable slopes.
The review found that a 2004 permit issued to Grandy Lake Forest Associates allowed for 7 ½ acres of timber to be harvested. Aerial photography showed 8 ½ acres were actually harvested.
Everett said there wasn’t enough information to determine whether that logging crossed into a restricted zone, known as the groundwater recharge zone. Logging in that zone would have triggered more environmental review because of concerns that groundwater could lead to more unstable slopes.
Everett said the period for enforcing the original permit has expired.
A call to the company on Tuesday was not immediately returned.
Grandy Lake initially proposed harvesting 15 acres upslope of the slide site. DNR rejected that application because it didn’t have required studies. The company later submitted a revised proposal that excluded a more restrictive area and was approved.
Peter Goldman, an environmental lawyer who directs the Washington Forest Law Center in Seattle, said that if the state had incorporated newer data to draw boundaries for a restrictive zone, more land near the slope would have been protected.
Newer data from a 1997 study and map, co-authored by geologist Daniel Miller, was considered, but there was conflicting information about why that information wasn’t used, Everett said in a call with reporters.
“They can’t explain why they didn’t do it,” Goldman said.
A July investigation by a team of scientists found a history of slides in the area, including 15 large mapped landslides over a span of about 6,000 years.
The scientists said heavy rain contributed to making the slope unstable. Other factors included groundwater seeping into the slide mass as well as changes in slope stress and soil that was weakened by previous landslides. They said it was possible that groundwater to the slope was increased by logging but that they couldn’t determine that within the scope of their study.
Everett said the agency’s review did find procedural shortcomings, including one case where a field review wasn’t conducted before a timber harvest application was approved.
“I don’t think the department has achieved perfection,” but the pattern of applications shows that regulatory protections were followed, Everett said.