I have heard DNR and timber industry representatives embrace the faulty logic that if a potentially unstable slope was harvested decades before and didn’t fail then it won’t fail if cut again. This is wishful thinking not thoughtful analysis.

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TWO-and-a-half years ago, the Oso landslide killed 43 people in a tragedy that prompted questions about the role of logging. Recently, the day before a jury trial was scheduled to begin, and after spending $3 million of taxpayers’ money on hired-gun experts, the state settled with victims’ families for $50 million. Perhaps this had something to do with the way it might appear to a jury that these experts systematically destroyed emails pertaining to how they shaped their case.

Now that the legal fight is over, I hope the state Department of Natural Resources and the Forest Practices Board will take a thorough and impartial look at what impact, if any, recent and past logging played in the disaster — and at the adequacy of DNR’s rules, guidelines and procedures for assessing potential impacts of timber harvest on landslides in general.

The controversial question of whether recent logging was a contributing factor is not the only one that needs to be credibly cleared up. What role did historical logging play? Did it reactivate portions of an ancient slide and help set up a series of modern slides that culminated in the Oso landslide decades later? This is not an academic question.

After the Oso disaster, DNR convened technical personnel from agency, industry and environmental interests to review sections of its “Forest Practices Board Manual” that lay out procedures for how to assess landslide hazards. When I read the revised manual this process produced, I was appalled that it failed to address the potential to reactivate ancient landslides.

The revised manual continues to allow timber harvest on landslides and in their groundwater recharge areas, with no requirement to assess potential reactivation of previously unstable, but now dormant, slopes. The guidance the manual provides directs staff to look for evidence of active or recent movement. In my experience, however, this translates into DNR only considering landslides showing such evidence as potentially risky to log.

Time and again over the years, I have heard DNR and industry representatives embrace the similarly faulty logic that if a potentially unstable slope were harvested decades before and didn’t fail then, it wouldn’t fail if cut again. This is wishful thinking, not thoughtful analysis. After all, it is well-established that whether a slope fails after clear-cutting depends, in part, on how much it rains.

Consider the proposed 2015 North Zender timber sale on DNR-owned land in Whatcom County. Despite the entire sale being located on large ancient landslides, DNR initially approved the sale based primarily on field reconnaissance that found both “no evidence of historic, recent, or ongoing movement” and that stumps from prior harvests showed logging in the past did not destabilized the slope.

Yet looking at a lidar terrain image (an aerial-mapping method) of the Zender site shows that the body of one of the ancient landslides pulled away from and undercut the upper portion of the slope. The fractured topography suggests the potential for destabilizing more of the slope should the old landslide begin moving again.

Why might it be prudent to rigorously analyze the potential to reactivate this ancient landslide before logging on it? An elementary school sits below its toe.

That DNR canceled this timber sale after it was challenged highlights the agency’s awkward mandate. It has a responsibility to generate income from state forests to support school construction, and it has the statutory responsibility to protect public safety and natural resources on both state and private land. This places its forest-practices division in the difficult position of both pushing for and regulating timber harvest.

What should be done? In my opinion, the state should convene independent academic experts to evaluate factors contributing to the Oso landslide. The state should also appoint an independent panel of geologists, which would review the rules and board manual that govern forest practices on landslides and potentially unstable slopes. The state should task the panel with recommending enforceable changes outside of the current industry-consensus process that preserves hardened agency habits.

Finally, after two decades watching DNR’s forest-practices division implement its conflicted mandate, I have come to the conclusion that assessing potential impacts of forest practices on slope stability should not be in its hands. The next state commissioner of public lands should seriously consider transferring this responsibility to the landslide-hazard program in DNRs geologic division.