Office of the City Manager

Windstorm Tree Analysis July 17

Windstorm Tree Analysis July 17


PASADENA, Calif.—Results of an independent analysis regarding the extensive tree damage sustained in Pasadena during the hurricane-force windstorm late last year will be presented at the next meeting of the Urban Forestry Advisory Committee.  The meeting begins at 6:00 p.m., Tuesday, July 17, at the City Yards complex, 233 W. Mountain Street. 

The report by the Davey Resource Group analyzed the damage to 5,500 trees located along streets and in parks that occurred during the severe winds from Nov. 30 to Dec. 1, 2011.  Of those 5,500 trees, about 1,500 mature trees were knocked down, uprooted or made unstable.  Another 525 mature trees were severely damaged and required removal.  The rest sustained less severe damage to branches or limbs.  

According to the report, “evidence showed that it would have been impossible to prepare for such a unique and devastating wind event.  In fact, the damage suffered to the City of Pasadena could have easily been worse had the City not had such an aggressive and effective tree maintenance program.” 

After the windstorm, the City undertook an after-action assessment to understand how to improve its response to similar future emergencies.  As part of this assessment, the City hired Davey Resource Group to investigate factors that may have contributed to the extensive tree damage.  

The report notes that Pasadena maintains an extensive urban forest with about 57,500 street trees representing more than 200 distinct species.  Tree maintenance follows the most current International Society of Arboriculture (ISA) Best Management Practices with most trees routinely pruned on a five-year cycle. 

During the Nov. 30 to Dec. 1, 2011 windstorm, strong sustained winds swept through the area causing significant damage to the City’s urban forest.  Official sustained wind speeds exceeding 60 miles per hour were recorded with some documented wind speeds topping 100 miles per hour.  Approximately nine percent of the City’s urban forest was lost or significantly damaged. 

The Urban Forestry Advisory Committee agenda and a PDF copy of the 27-page Pasadena Windstorm Tree Failure Analysis Report are available online at http://cityofpasadena.net/UFAC/. 

For more information about the City, go to  www.cityofpasadena.net. 




William H. Boyer, Pasadena Public Information Officer, City Manager’s Office, (626) 744-4755,  wboyer@cityofpasadena.net 


Posted: 7/13/2012 09:55:00 AM