When enough dog poop enters local waterways, plant and animal life can start to falter. This is in part because dog poop adds nitrogen and phosphorus to the water, which in high enough concentrations depletes oxygen levels necessary to sustain plant life, fish and other wildlife.

Additionally, any of the pathogens commonly found in dog poop can survive in water. For example, Roundworm, one of the most common parasites found in dog poop, can remain infectious in contaminated soil and water for years.