Does a reduction in the amount spent on tree trimming affect the reliability of the system?

Trees have the biggest impact on the reliability of our system as measured by the number and length of service interruptions our members experience. The System Average Interruption Duration Index (SAIDI) is one common metric used to measure the impact of service interruptions and is the total number of minutes of service interruptions experienced by all members on an annual basis divided by the number of members. The table below shows the amount spent on tree trimming and the cooperative’s SAIDI metrics from 2012 through 2018.

Year Expenditures SAIDI
2018 $1,226,922 189.50
2017 $1,092,577 178.50
2016 $1,118,811 324.20
2015 $700,923 197.10
2014 $1,528,713 229.70
2013 $1,639,516 239.40
2012 $1,560,000 269.57

Because there is a lagging effect (lack of tree trimming one year has the potential to increase the number and duration of service interruptions in subsequent years), an increase in the SAIDI usually occurs a year or two after a significant decrease in the amount spent on tree trimming. Cloverland has a benchmark SAIDI of 207 minutes and because of decreased spending in some historical years and a higher SAIDI than benchmark, the board authorized an increase in the 2019 tree trimming budget.