Vegetation Management
Leading Indicator: Vegetation Management

View Data on Grow-Ins Only >>

Vegetation related outages typically follow the growing season of trees and shrubs in North America, thus a much higher number of outages typically occur in the third quarter (July through September) than in any other quarter. The figures above represent a sum of three categories of transmission line outages caused by vegetation, either growing into the line, falling into the line from within the right of way, or falling into the line from outside the right of way. This data generally does not reflect outages caused by major storms or natural disasters, such as hurricanes or tornadoes.

As more data becomes available on specific violations of NERC's vegetation management standard (FAC-003-01), more options to view different aspects of this data will be made available on this page. NERC's goal is to have not one, but consecutive quarters with no vegetation management violations and no vegetation-related transmission outages.

The number of vegetation related transmission outages between 2004 and the first quarter of 2006 includes Fall-Ins outside of ROW due to severe weather conditions and logging activities, which may not be reportable in accordance with standard FAC-003-1.


About this Leading Indicator

Conductor contact with trees has been an initiating trigger and a contributing factor in several major system disturbances since 1965, including the blackout of August 14, 2003. Tree contact caused the loss of multiple transmission circuits in several of the outages, causing multiple contingencies and further weakening of the system. By carefully tracking and enforcing standards related to inadequate vegetation management, we are able to identify and eliminate the causes, with the goal of preventing line outages from vegetation located on transmission rights-of-way (ROW) and minimizing outages from vegetation located adjacent to ROW.

NERC began collecting vegetation-related outage information in 2004 as a result of the August 14, 2003 Blackout. NERC continues to aggressively pursue the reduction of vegetation-related transmission outages through compliance and enforcement programs that launched on June 18, 2007.

NERC continues to broaden its effort to reach at-risk registered entities. Targeted initiatives include quarterly vegetation management reports (available here) along with detailed outage and compliance information. In 2007, NERC and the Regional Entities conducted over eighty compliance audits, focusing on each requirement of NERC standard FAC-003-1. Compliance monitoring also includes periodic (monthly/quarterly) data reporting and self certification of vegetation-related outages by transmission owners.