Information about owl sightings is usually very secretive among naturalist groups because of the human disturbances to wildlife and private property (which I totally agree). Observing wildlife in their habitat is a great way for people to learn about nature, but it is importance to treat wildlife as other human beings and keep a respectful, non-disruptive distance because I doubt most people would like it when others start to invade their personal space. The Ottawa Field-Naturalists' Club has listed code of conduct and ethics here.
Nonetheless, there are usually some clues left on internet (e.g., eBird, Flickr, general news media) that give people an idea of where to look for them. Then the rest is just being at the right place at the right time. I followed this news article, and looked for owls south of the airport today. It took me some searching, but I eventually saw this Snowy Owl about 200-m away from where I stood.
This was as far as I could get with my 70-300 lens (i.e., 140-600 lens).
Sitting and watching around.
Three crows briefly mobbed it while they flew by but the owl stayed still. It flew to a hay bale shortly after I walked to another spot.
Such a beautiful creature!