Alberta's Wild horses may indeed be the best hope for keeping the water shed protected and thriving in an era where providing fresh water is challenged increasingly as development spreads through out the world.
I first heard about Wild horses being used to do these things about 10 years ago from a source in South America. Wild horses have been used to rebuild forests with the least impact and most benefit to the land in areas of fragile clear cut South and Central American Rain forests. Just last autumn I learned about the move to re-establish the European Wild Forest Horses in order to protect and reestablish receding marsh and and grass park lands of Europe.
Rather than try to rewrite the whole thing I am going to defer to the experts tonight. There is a wonderful video that Ken Mcleod shared with me of an ongoing study in the Crown's Forest of Alberta where the wild horses run. The video explains the benefits of maintaining the forests of Alberta using the existing wild horses with the least amount of trauma to the land.