Landslides to Logjams

Back to Campaigns


An estimated 50 percent of instream large wood comes from landslides on forested slopes. Heavily forested watersheds grow trees up to 500 or even 1000 years old. Western Oregon, Washington, and California salmon streams are built on this architecture of large woody debris. Unfortunately, a clearcut landslide dumps massive amounts of sediment and, unsurprisingly, very little wood into rivers. Landslides on clearcut slopes are much larger and more frequent than slides on forested slopes. In fact, studies show that landslides occur up to 24 times more frequently after an area has been logged. Moreover, the sediment loads dumped into streams by a clearcut landslide often channelize rivers, impair water quality and either wipe-out or bury existing logjams.

Human-caused landslides on clearcut slopes destroy spawning habitat by smothering spawning gravel with fine sediment. Sedimentation also reduces the available rearing space for juvenile salmonids by burying cobble and filling rearing pools. When sediment fills pools and creates broader, shallower channels, it deprives salmonids of vital overwintering habitat, disrupts feeding and rearing, and exacerbates stream temperature problems. By entombing juvenile salmon and steelhead embryos, this activity prevents the recovery of threatened species.


  • Improve habitat complexity for listed Species such as Oregon Coast Coho
  • Protect landslide prone slopes from clearcut logging
  • Improve water quality on 303(d) listed streams

Map of Current Problem:

In February of 2018, the Native Fish Society partnered with Lighthawk to fly over the Oregon Coast range documenting problems with the Oregon Forest Practices Act. Click on the map below to see a bird's eye view of logging operations which affect water quality and endangered coho salmon. If you have additional photos documenting landslides, or poor forest practices in the Oregon Coast range, please email us the latitude/longitude of the incident so we can work with you to add it on the map.

Key Documents:

Join Us for a Guaranteed Good Time for a Great Cause! Where: The Miracle Barn at 65599 Tweed Road, Bend, OR / *Virtual auction available anywhere you have wifi! When: Saturday, August 17th, 4 - 7pm What: A FREE Central Oregon benefit for our wild, native fish, free-flowing rivers, and thriving communities.