Legality of storm drain exploration

I’m curious about the legality of exploring underground storm sewers, and other underground serviceways such as buried waterways, utility corridors, and secret/forgotten tunnels built to move people and cargo.

The jurisdictions I am specifically interested in are Alberta and Ontario, though I am also interested in the general legal attitude towards such behaviour. Does it fall under trespassing or under more specific legislation?

Does it make a difference if the tunnel is on public property, or privately owned? (I imagine it would.) What if the tunnel was built for a public use (such as a storm sewer) but runs beneath private property?

Note: I’m well aware of the physical dangers of such an activity, and am only interested in the legality of it for this discussion.

If you get caught expect a fine at least. Things got a lot nastier for explorers after the terrorist attacks. Look at urban explorer clubs.

This is for the first site I Googled.

Public entities don’t want a situation where a public drain is on private property with no access. So, usually an easement is held by the public entity. This gives them the right to maintain the structure. However, in some cases you will find a public drain which is not within any easement. In the U.S. we can argue that there exists a prescriptive easement, if the drain has been in place for a sufficient time. I do not know if Canadian law is similar.

I’m not a lawyer. I used to be in charge of the storm drain system for our city.

Speaking of Urban Exploration, does anyone know what happened to Undergroud Ozarks?