How we assess and maintain trees near power lines
Trees, power lines and outages
A tree falling on a power line is one of the main causes of outages in B.C. – especially when the wind and rain pick up during the fall and winter months.
And it's not just an inconvenience; fallen trees are a huge safety risk too. The tree can become energized by the line and potentially ignite a fire or even electrocute those nearby.
Assessing and maintaining the trees and plants around our equipment to minimize these risks is the job of our vegetation management teams.
Is that tree healthy?
Identifying 'hazard trees' is a key part of the work performed by our teams. But just what makes a tree hazardous?
"A hazard tree is defined as a tree that has a structural defect that may cause the tree (or part of a tree) to fall on a power line or other nearby structure. At BC Hydro, we use a risk rating system that allows us to assess and identify these trees and then prioritize our work based on that rating," explains Jeff Labelle, who manages the team responsible for assessing and maintaining trees and plants growing near our equipment on Vancouver Island.
"As you can imagine in a place like B.C. where we have power lines traveling through such densely forested areas, we can't have eyes on every tree, and assessing each tree for a potential hazard is next to impossible," says Labelle. "When there's an outage caused by a fallen tree, we'll take the time to analyze the situation afterwards and assess what we could have done differently for next time."
Quick tips for identifying a hazard tree
While identifying and removing hazard trees is a job best left to a professional arborist, there are a few general tips to help you assess the condition of trees on your property as we head into the winter months:
Check the top of the tree:
- Are there dead branches? These are risky, can fall without warning and should be removed.
- Are there branches that cross or rub? They can cause weak spots in the tree's internal structure and should be pruned off.
- Is the tree dead or dying? A dead or dying tree is extremely weak and should be considered dangerous. Contact a professional to have the tree removed.
Check the trunk and roots:
- Look for forked trunks: it's a sign of potential weakness, especially if one side grows outward instead of upward.
- Signs of decay: disfigurations in the tree's trunk a sign that the inside of the tree is starting to decay.
- Leaning or lopsided: a sudden lean can indicate breakage or weakening of the trees roots. If you notice this, contact a professional right away.
- Look for mushrooms: fungus growing on the trunk or at the base around the tree is a sign that the tree is decaying.
Safety is top priority
Our vegetation management teams must often decide whether to prune or remove a tree, and they don't take such decisions lightly. We employ qualified, professional utility arborists who follow strict safety protocols and pruning practices to help ensure the tree's health isn't compromised.
"Our foremost concern is always safety. We don't like when we have to top trees, but when a tree is growing close to one of our lines, it becomes a safety issue and we need to take the necessary steps," explains Labelle.
Unfortunately, the pruning necessary to ensure safety isn't always the most aesthetically pleasing.
"We do our best to retain the tree as best we can, and this means only taking off what is needed to eliminate the safety concern," says Labelle. "We understand that to a customer it can sometimes be concerning to see a tree on their property pruned back, but when we explain that it was done in the interest of safety, they’ll typically understand."
On the rare occasion, a tree may need to be removed together.
"If after our assessment we conclude that the best option is to remove the tree all together, we'll contact the individual customer and discuss our findings with them," explains Labelle. "A vegetation coordinator will then work with the customer to recommend a species of plant that can be planted in its place that's better suited to grow near power lines."
Planting near power lines
"Plant the right tree in the right place".
Considerations such as the availability of light and water, and soil type, are important when picking out a new plant or tree for your property. But if you're planting near power lines, there's even more to consider [PDF, 1.6 MB].
Being able to identify the different types of power lines near your home is also important so you know the maximum allowable height for trees nearby, as well as the minimum distance you can plant from a power pole.
The unusually dry weather we experienced this past summer has put a lot of stress on trees, and it created soil that is less able to hold trees in place and branches that are weak, putting them at a higher risk of falling or breaking. Forecasters are also calling for wild, El Niño-like weather, which could make for a challenging winter. Ensure you and your family are prepared if the lights do go out.