First of all, it’s important to remember that the air around the high-voltage power transmission lines acts as an insulator. As a result, if a tree branch is too close to a high-voltage line, even if it isn’t touching it, electric arcing can occur, which in turn can cause a fire or a power outage that could affect thousands of customers. That’s why Hydro-Québec must cut trees that present a risk for the reliability of its transmission lines.
To answer your question in more detail, we already design our transmission lines in such a way that short trees and shrubs can grow underneath. If we wanted to allow for tall-growing trees, the power lines would have to be much higher. The towers needed to support those lines would therefore be extremely high, which would have major disadvantages. For instance, the lines would be visible from kilometres away and the construction costs would be extremely high. Consequently, that scenario isn’t feasible.
However, we encourage the presence of vegetation under our transmission lines, and we are happy to communicate with landowners who would like to carry out landscaping work compatible with our system. For more information on vegetation and high-voltage transmission lines, visit our Web site.