Sunday afternoon, as we left Cathcart Street, we saw a long line of people, far more than normal, taking their dogs for a walk by the river. There must be some reason for that, I assumed, and sure enough I discover that the Cumberland Lions Club organised this event to raise money for guide dogs, or dog guides, as they prefer to call them: a stroll from the De La Salle school opposite the Chinese Embassy following the river banks back to the Rockcliffe Retirement Residence on Porter Island—more or less our usual evening walk, in fact.
Here is a map showing the route of the dog walk.
I noticed that all the dogs were on leashes on this occasion; that's not always the case, but near our house it ought to be. Undisciplined, off-leash dogs can be a hazard to people and to themselves. An over-excited dog could veer off into the traffic on King Edward Island if it's not kept under control, or in early / late winter could run onto the thin ice of the (deep, cold, rushing) river and fall through, closely followed by its owner (trying to rescue it) in some cases. Such tragedies have been known to happen.
According to this map dogs are allowed to run free in Bordeleau Park and in New Edinburgh Park across the river. The Ottawa Bylaw 2003 - 77 has a good deal to say on the subject of dogs and parks: see sections 42-48 of that document.