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.
It takes more effort to put the poop in a bag than it does to fucking carry it to a garbage.
At that point just leave the poo so it degrades and gives back nutrients to the environment. Double the nutrients when it’s on someone’s lawn 😎
Unfortunately, leaving dog crap around is a public health concern and should be heavily fined.