Bordeleau Park

Tucked away in the back side of Lowertown near the Chinese Embassy, this is a great off leash park.
A very quiet neighbourhood, traffic wise, no need to worry about pets that accidentally stray across the bordering streets.
Also on the river, so pets can refresh themselves on a hot day.
Shared space with tennis courts and a park for small children, note that this park has one of the only interactive Water Features in Ottawa (a great place for kids to cool off in the summer) Many families are wary of dogs, so be sure to keep your animal under control and on the open soccer field area.
The park and park that continues northeast along the river is not off leash designated, so be wary of this.
You also share the park with vagrants who use this park at night, but they usually keep their trash to a minimum. Occasionally a used needle can be seen, but almost always capped. The Shepherds of Good Hope run a great program where volunteers patrol the park a number of times daily, collecting this refuse.
I live a block away and have only seen one since I have taken my dog daily.
A great offleash park