Harm to Lawn/grass 

Dog waste contains high levels of nitrogen. When to much nitrogen is produced into the lawn it will cause the lawn to become yellow and eventually die away and need to be replanted and possibly giving your dog a new hole to dig. 

Bacterias 

Different types of bacteria including e.coli and salmonella can be in the dog waste which are both things people have to look out for and by leaving it could possibly get into drinking water. 

Run Off Water 

If you have a well leaving dog waste in your yard is a terrible idea. As it rains the waste becomes wet and muddy soaking into the ground polluting your drinking water and other water sources which can cause many different health problems for you and wild animals.  

The smell 

There is nothing like walking outside on a nice foggy spring morning, that is until, the smell knocks you off your socks. Obviously dog waste is not a rose and has a terrible smell. that many people become 

The Hassle 

After working all day, running around to getting everyone to practice, making dinner and hanging out with family there is little time left in the day to take care of the dog waste and on weekends when you want to play/hangout in the yard you don't want to be stopped to pick up after the dog. 

Rodents 

Dog waste can attract rodents like rats and mice to your yard. Once they know a food source is close they will start to live closer and closer removing one problem while creating a way bigger one.