Have you ever thought about where your waste goes? For people living in cities, it goes to a treatment plant. However, treated wastewater ultimately finds its way into a local waterway. This means it could end up in your nearby stream, river, or lake.

Although wastewatertreatment reduces the threat of disease, another problem remains: nutrients. Wastewater contains a lot of nutrients (nitrogen and phosphorus), including from pee and poop. All plants and animals need nutrients to grow and thrive; however, too much of a good thing is a big problem, particularly for waterways. Rivers get sick when too many nutrients impair the ecosystem. One of the worst offenders is excess ammonia.

"Ammonia is a nitrogen compound produced by the breakdown of organic matter in sewage. Discharge of ammonia into waterways can have direct toxic effects but also cause significant oxygen depletion that threatens the survival of aquatic life, including fish," says Helen Jarvie. A professor of water science at the University of Waterloo in Canada, Jarvie studies how these nutrients affect waterways.

The study was published in the Journal of Environmental Quality.