A federal agency says elevated levels of uranium found in a spring on the northern edge of Grand Canyon National Park is likely due to a natural source of the radioactive element and not related to an inactive mine.
The U.S. Geological Survey says Pigeon Spring had elevated levels in samples taken from 2012 to 2014 compared with similar springs in the area.
The Grand Canyon is the location of part of the Colorado River, a primary water source for millions of people in the United States and Mexico.
The area is also believed to host high-grade uranium ore, and the Geological Survey says understanding the potential impact that uranium mining could have on water resources is important for managing interests of the mining industry, water managers and others.