I live in Ontario, and this is also a huge problem here.
The solution is to ban dogs from all trails except dog parks, because people won’t change, and this problem extends to more than just other trail users; it also contaminates the land and water, too.
Fwiw, I do community cleanups, so I’m not the problem.
And I guarantee the same people who are leaving dog shit bags on trails are the same people leaving other litter on trails, too.
I’m totally fine with banning those people from these places. Just make sure we fine them, too. 👌