If fertilizer runs off a farm in southwestern Montana, it could end up traveling more than 3,400 miles through streams and rivers in North Dakota, South Dakota, Iowa, and Missouri, and then down the Mississippi River to the Gulf of Mexico, where it might end up contributing to a giant algae-filled dead zone. Plastic trash that lands in a stream in West Virginia might make a similarly long journey—around 3,000 miles—to the same place.
Using data from the United States Geological Survey, and with help from the USGS’s water data team, he mapped the flow path of water from every location in the U.S. Though it illustrates the idea that a drop of rain will follow this path, it’s worth noting that some water might evaporate, or end up in a water treatment plant, or go into groundwater, or otherwise not make the whole journey; Learner is now working on another project that tracks how water is pulled out.
It’s mesmerizing to watch the path of the water as the tool virtually flies along streams and rivers. But it’s also a reminder that pollution in a waterway in one corner of the country isn’t necessarily just a local problem. “What I really hope people take away from the tool, besides a fun visual experience, is just how interconnected our waterways are, and the implications of that in terms of pollutants, agriculture, or water use,” Learner says.