Tree Disputes With Neighbours: Calgary's Rules

Few things sour a neighbourly relationship faster than a tree dispute. Maybe their spruce is dropping needles all over your deck. Maybe their poplar roots are clogging your sewer line. Maybe a dead branch from their elm is hanging over your garage and they do not seem concerned. Whatever the situation, the question is always the same: whose responsibility is it, and what are you allowed to do?

Here is how tree disputes work in Calgary, based on Alberta law and City of Calgary bylaws.

The Basic Rule: You Own What Is on Your Side

In Alberta, the legal principle is straightforward. A tree belongs to the person on whose property the trunk is located. If the trunk straddles the property line, the tree is jointly owned. But here is the important part: you have the right to trim any branches or roots that cross onto your property, up to the property line.

This means if your neighbour's tree has branches hanging over your fence and into your yard, you can cut them back to the property line. You do not need your neighbour's permission. However, there are important limitations:

• You can only cut up to the property line, not beyond it
• You are responsible for the cost of the trimming on your side
• You cannot enter your neighbour's property to do the work
• You must not damage the tree in a way that could kill it (over-pruning, improper cuts, or cutting the trunk)
• You are liable if your trimming causes the tree to die or become hazardous

What About Falling Leaves, Needles, and Seeds?

This is one of the most common complaints, and unfortunately, there is no legal remedy. Falling leaves, seeds, pollen, and needles from a neighbour's tree are considered a natural occurrence. You cannot require your neighbour to clean up natural debris that falls on your property, and you cannot force them to remove a healthy tree because you do not like the mess.

The same applies to shade. If a neighbour's tree shades your garden or solar panels, that is not something you can compel them to address. Trees grow, and shade is a natural consequence.

Roots That Cause Damage

Roots are where things get more complicated. If a neighbour's tree roots grow onto your property and cause damage, such as cracking your foundation, lifting your driveway, or infiltrating your sewer line, you may have a legal claim for damages. However, proving that specific roots caused specific damage can be difficult and expensive.

As a practical matter, you can cut roots that have grown onto your property, but do so carefully. Cutting major structural roots can destabilize the tree and make you liable if it falls. If significant root cutting is needed, it is worth consulting an arborist first to understand the implications.

Hazardous Trees: When Your Neighbour Must Act

The rules change when a tree is genuinely hazardous. Under Alberta common law, property owners have a duty of care to prevent their trees from causing foreseeable harm. If a tree is dead, structurally compromised, or has large dead branches hanging over a neighbour's property, the tree owner can be held liable for damages if the tree or branch falls and causes injury or property damage.

In practice, this means:

1. Notify your neighbour in writing. If you believe their tree is hazardous, put your concerns in writing (email or letter). Be specific about what you see and what you are worried about. This creates a record that the tree owner was aware of the risk.
2. Contact the City of Calgary. The City's 311 service can dispatch an urban forestry inspector for trees that pose a risk to public safety. If the tree is on private property, the City's ability to intervene is limited, but a documented complaint creates a record.
3. Get an arborist assessment. Having a certified arborist assess the tree and provide a written report strengthens your position. An arborist can objectively evaluate the risk level and recommend appropriate action.

Trees on City Property

If the tree causing the issue is on City of Calgary land (boulevards, parks, or utility corridors), the rules are different. You cannot prune or remove a City tree. All work on City-owned trees must be performed by or authorized by the City's Parks department. Contact 311 to report concerns about City trees, including dead branches, disease, or hazardous conditions.

The City typically responds to reports of hazardous boulevard trees relatively quickly, especially if there is a clear safety risk.

The Elm Exception

Calgary's Dutch elm disease bylaws add another layer to neighbour tree disputes. If you suspect your neighbour's elm is infected with Dutch elm disease (signs include rapid wilting and browning of leaves on one or more branches during summer), report it to 311 immediately. The City takes Dutch elm disease very seriously and has the authority to order removal of infected trees on private property.

Practical Advice for Resolving Disputes

Before lawyering up, try these approaches:

• Talk to your neighbour. Most tree disputes can be resolved with a conversation. Many people are simply unaware that their tree is causing a problem.
• Offer to split the cost. If a tree needs pruning to address overhanging branches, offering to share the expense often gets faster results than arguing about responsibility.
• Get a professional opinion. Having an arborist look at the situation provides an objective assessment that takes emotion out of the conversation.
• Use community mediation. Calgary offers community mediation services for neighbour disputes. It is free, confidential, and often more effective than going to court.
• Document everything. If the situation is not resolved informally, keep records of all communications, take dated photos, and save any arborist reports. This documentation is essential if the matter escalates to a legal claim.

The best tree disputes are the ones that never happen. If you have a large tree near the property line, be proactive about maintaining it. Have it pruned regularly, remove deadwood promptly, and communicate with your neighbours. An ounce of prevention is worth a pound of legal fees.