Since 1987, arborists in California have been tracking tree failures using the California Tree Failure Report Program. In 2012, tree failure data from California was merged with the International Tree Failure Database (ITFD).

Unfortunately, the ITFD was taken off-line by the U.S. Government in 2015 with no plans to restore it in the foreseeable future.

These systems to collect and aggregate tree failure data have the potential to help arborists learn more about how different tree species perform in the landscape. By understanding how trees tend to fail under different circumstances, tree risk assessors may be better able to forecast future tree failures and prescribe maintenance actions to prevent them.

In November 2017, a trio of arborists from the Pacific Northwest—Chris Rippey, City of Seattle; Dylan Saito, City of Portland; and, Jon Pywell, City of Corvallis—joined forces to launch the Pacific Northwest Tree Failure Database.

PNW Tree Failure Rates by Date


This database uses an online collection tool that is quick, intuitive and user friendly, allowing a user to enter a tree failure report in under a minute.

Users are asked to report species, DBH (diameter), condition, height, and part of the tree that failed (roots, trunk or branch). The user is then asked to enter factors which many have contributed to the failure, such as weather conditions, structural defects, site conditions, decay associated with the failure, and if so, which decay organism is responsible.

There are over 1,800 tree failure reports in our database collected since May 2015 (pre-2017 data imported from municipal records). These reports come from all over the Pacific Northwest with many reports from the Puget Sound area of Washington, the Portland metro area, Corvallis, Victoria, B.C., and Vancouver B.C.

To date, no reports have been filed from areas east of the Cascade Mountains in Oregon or Washington, nor from Idaho or Alaska. If you are in one of these areas, or know someone there, please help promote this database.

One key objective of the PNW Tree Failure Database is to eventually create species failure profiles, as has been done in California. However, more data is needed before this can be achieved.

If you would like to help improve the state of knowledge regarding tree failures in the Pacific Northwest, or have any questions about the PNW Tree Failure Database, please visit our website at or email Chris Rippey at


By Chris Rippey


Chris Rippey is a third-generation arborist with over twenty years of experience in arboriculture that began by working for his dad’s company in Palo Alto, California. Chris moved to Washington in 2016 to work for the City of Seattle Parks Department as an Arboriculturalist, and currently serves as Secretary on the Board of Directors for the Pacific Northwest Chapter of the International Society of Arboriculture.